Macrophage activation by endogenous danger signals

Anti-inflammatory effects of Daehwangmokdantang, a traditional herbal formulation, in lipopolysaccharide-stimulated RAW 264.7 macrophages

Daehwangmokdantang (DHMDT) is a traditional polyherbal formulation that has known antidiarrheal and anti-inflammatory activities. However, the underlying mechanisms of these activities are poorly understood. In the present study, the inhibitory effects of DHMDT on the production of proinflammatory mediators and cytokines in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages were investigated. The inhibitory effects of DHMDT on LPS-induced nitric oxide (NO), prostaglandin (PG)E₂, tumor necrosis factor (TNF)-α and interleukin (IL)-1β production were examined using Griess reagent and ELISA detection kits. The effects of DHMDT on the expression of inducible NO synthase (iNOS), cyclooxygenase (COX)-2, IL-1β and TNF-α, and their upstream signal proteins, including nuclear factor (NF)-κB, mitogen-activated protein kinases (MAPKs) and RAC-α serine/threonine-protein kinase (Akt), a phosphatidylinositol 3-kinase (PI3K) downstream effector, were investigated using western blotting and immunofluorescence staining. The results revealed the pretreatment with DHMDT significantly inhibited the LPS-induced production of NO, PGE₂, TNF-α, and IL-1β, and expression of iNOS, COX-2 TNF-α, and IL-1β, without any significant cytotoxicity. DHMDT also efficiently prevented the translocation of the NF-κB subunit p65 into the nucleus by interrupting the activation of the upstream mediator inhibitor of NF-κB kinase α/β. Furthermore, the anti-inflammatory effects of DHMDT were associated with the suppression of LPS-induced phosphorylation of Akt and MAPKs in RAW 264.7 macrophages. Therefore, the results of the present study indicate that DHMDT exhibited anti-inflammatory activity via the inhibition of proinflammatory mediators and cytokines, in which the inactivation of NF-κB, PI3K/Akt, and MAPKs may be involved. These results suggest that DHMDT may be a potential anti-inflammatory drug candidate.

Macrophage-Associated Osteoactivin/GPNMB Mediates Mesenchymal Stem Cell Survival, Proliferation, and Migration Via a CD44-Dependent Mechanism

Although MSCs have been widely recognized to have therapeutic potential in the repair of injured or diseased tissues, it remains unclear how functional activities of mesenchymal stem cells (MSCs) are influenced by the surrounding inflammatory milieu at the site of tissue injury. Macrophages constitute an essential component of innate immunity and have been shown to exhibit a phenotypic plasticity in response to various stimuli, which play a central role in both acute inflammation and wound repair. Osteoactivin (OA)/Glycoprotein non-metastatic melanoma protein B (GPNMB), a transmembrane glycoprotein that plays a role in cell differentiation, survival, and angiogenesis. The objective of this study was to investigate the potential role of OA/GPNMB in macrophage-induced MSC function. We found that reparative M2 macrophages express significantly greater levels of OA/GPNMB than pro-inflammatory M1 macrophages. Furthermore, using loss of function and rescue studies, we demonstrated that M2 macrophages-secreted OA/GPNMB positively regulates the viability, proliferation, and migration of MSCs. More importantly, we demonstrated that OA/GPNMB acts through ERK and AKT signaling pathways in MSCs via CD44, to induce these effects. Taken together, our results provide pivotal insight into the mechanism by which OA/GPNMB contributes to the tissue reparative phenotype of M2 macrophages and positively regulates functional activities of MSCs. J. Cell. Biochem. 117: 1511-1521, 2016. © 2015 Wiley Periodicals, Inc.

A past and present overview of macrophage metabolism and functional outcomes

In 1986 and 1987, Philip Newsholme et al. reported macrophages utilize glutamine, as well as glucose, at high rates. These authors measured key enzyme activities and consumption and production levels of metabolites in incubated or cultured macrophages isolated from the mouse or rat intraperitoneal cavity. Metabolic pathways essential for macrophage function were then determined. Macrophages utilize glucose to generate (i) ATP in the pathways of glycolysis and mitochondrial oxidative phosphorylation, (ii) glycerol 3-phosphate for the synthesis of phospholipids and triacylglycerols, (iii) NADPH for the production of reactive oxygen species (ROS) and (iv) ribose for the synthesis of RNA and subsequently production and secretion of protein mediators (e.g. cytokines). Glutamine plays an essential role in macrophage metabolism and function, as it is required for energy production but also provides nitrogen for synthesis of purines, pyrimidines and thus RNA. Macrophages also utilize fatty acids for both energy production in the mitochondria and lipid synthesis essential to plasma membrane turnover and lipid meditator production. Recent studies utilizing metabolomic approaches, transcriptional and metabolite tracking technologies have detailed mitochondrial release of tricarboxylic acid (TCA) intermediates (e.g. citrate and succinate) to the cytosol, which then regulate pro-inflammatory responses. Macrophages can reprogramme their metabolism and function according to environmental conditions and stimuli in order to polarize phenotype so generating pro- or anti-inflammatory cells. Changes in macrophage metabolism result in modified function/phenotype and vice versa. The plasticity of macrophage metabolism allows the cell to quickly respond to changes in environmental conditions such as those induced by hormones and/or inflammation. A past and present overview of macrophage metabolism and impact of endocrine regulation and the relevance to human disease are described in this review.

Macrophage Phenotypes Regulate Scar Formation and Chronic Wound Healing

Macrophages and inflammation play a beneficial role during wound repair with macrophages regulating a wide range of processes, such as removal of dead cells, debris and pathogens, through to extracellular matrix deposition re-vascularisation and wound re-epithelialisation. To perform this range of functions, these cells develop distinct phenotypes over the course of wound healing. They can present with a pro-inflammatory M1 phenotype, more often found in the early stages of repair, through to anti-inflammatory M2 phenotypes that are pro-repair in the latter stages of wound healing. There is a continuum of phenotypes between these ranges with some cells sharing phenotypes of both M1 and M2 macrophages. One of the less pleasant consequences of quick closure, namely the replacement with scar tissue, is also regulated by macrophages, through their promotion of fibroblast proliferation, myofibroblast differentiation and collagen deposition. Alterations in macrophage number and phenotype disrupt this process and can dictate the level of scar formation. It is also clear that dysregulated inflammation and altered macrophage phenotypes are responsible for hindering closure of chronic wounds. The review will discuss our current knowledge of macrophage phenotype on the repair process and how alterations in the phenotypes might alter wound closure and the final repair quality.

Anti-Inflammatory Activity of Citric Acid-Treated Wheat Germ Extract in Lipopolysaccharide-Stimulated Macrophages

Until recently, fermentation was the only processing used to improve the functionality of wheat germ. The release of 2,6-dimethoxy-1,4-benzoquinone (DMBQ) from hydroquinone glycosides during the fermentation process is considered a marker of quality control. Here, we treated wheat germ extract with citric acid (CWG) to release DMBQ and examined the anti-inflammatory activity of this extract using a lipopolysaccharide-activated macrophage model. Treatment of wheat germ with citric acid resulted in detectable release of DMBQ but reduced total phenolic and total flavonoid contents compared with untreated wheat germ extract (UWG). CWG inhibited secretion of the pro-inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-6, and IL-12 and the synthesis of cyclooxygenase-2, while UWG only decreased IL-12 production. CWG and UWG induced high levels of anti-inflammatory IL-10 and heme oxygenase-1. CWG specifically inhibited phosphorylation of NF-κB p65 and p38 kinase at 15 min after LPS stimulation. Our study showed that citric acid treatment enhanced the anti-inflammatory activity of wheat germ extract.

Pathological manifestations in lymphatic filariasis correlate with lack of inhibitory properties of IgG4 antibodies on IgE-activated granulocytes

Helminth parasites are known to be efficient modulators of their host's immune system. To guarantee their own survival, they induce alongside the classical Th2 a strong regulatory response with high levels of anti-inflammatory cytokines and elevated plasma levels of IgG4. This particular antibody was shown in different models to exhibit immunosuppressive properties. How IgG4 affects the etiopathology of lymphatic filariasis (LF) is however not well characterized. Here we investigate the impact of plasma and affinity-purified IgG/IgG4 fractions from endemic normals (EN) and LF infected pathology patients (CP), asymptomatic microfilaraemic (Mf+) and amicrofilaraemic (Mf-) individuals on IgE/IL3 activated granulocytes. The activation and degranulation states were investigated by monitoring the expression of CD63/HLADR and the release of granule contents (neutrophil elastase (NE), eosinophil cationic protein (ECP) and histamine) respectively by flow cytometry and ELISA. We could show that the activation of granulocytes was inhibited in the presence of plasma from EN and Mf+ individuals whereas those of Mf- and CP presented no effect. This inhibitory capacity was impaired upon depletion of IgG in Mf+ individuals but persisted in IgG-depleted plasma from EN, where it strongly correlated with the expression of IgA. In addition, IgA-depleted fractions failed to suppress granulocyte activation. Strikingly, affinity-purified IgG4 antibodies from EN, Mf+ and Mf- individuals bound granulocytes and inhibited activation and the release of ECP, NE and histamine. In contrast, IgG4 from CP could not bind granulocytes and presented no suppressive capacity. Reduction of both the affinity to, and the suppressive properties of anti-inflammatory IgG4 on granulocytes was reached only when FcγRI and II were blocked simultaneously. These data indicate that IgG4 antibodies from Mf+, Mf- and EN, in contrast to those of CP, natively exhibit FcγRI/II-dependent suppressive properties on granulocytes. Our findings suggest that quantitative and qualitative alterations in IgG4 molecules are associated with the different clinical phenotypes in LF endemic regions.

3'UTR AU-Rich Elements (AREs) and the RNA-Binding Protein Tristetraprolin (TTP) Are Not Required for the LPS-Mediated Destabilization of Phospholipase-Cβ-2 mRNA in Murine Macrophages

We have shown previously that bacterial lipopolysaccharide (LPS)-mediated suppression of phospholipase-Cβ-2 (PLCβ-2) expression is involved in M1 (inflammatory) to M2-like (wound healing) phenotypic switching of macrophages triggered by adenosine. This suppression is mediated post-transcriptionally by destabilization of PLCβ-2 mRNA (messenger ribonucleic acid). To investigate the mechanism of this LPS-mediated destabilization, we examined the roles of RNA-binding agents including microRNAs and RNA-binding proteins that are involved in regulating stability of mRNAs encoding growth factors, inflammatory mediators, and proto-oncogenes. Adenylate and uridylate (AU)-rich elements (AREs) in 3'UTRs are specific recognition sites for RNA-binding proteins including tristetraprolin (TTP), HuR, and AUF1 and for microRNAs that are involved in regulating mRNA stability. In this study, we investigated the role of TTP and AREs in regulating PLCβ-2 mRNA stability. The 3'UTR of the PLCβ-2 gene was inserted into the pLightswitch luciferase reporter plasmid and transfected into RAW264.7 cells. LPS suppressed luciferase expression from this reporter. Luciferase expression from mutant 3'UTR constructs lacking AREs was similarly downregulated, suggesting that these regions are not required for LPS-mediated suppression of PLCβ-2. TTP was rapidly upregulated in both primary murine macrophages and RAW264.7 cells in response to LPS. Suppression of PLCβ-2 by LPS was examined using macrophages from mice lacking TTP (TTP^-/-). LPS suppressed PLCβ-2 expression to the same extent in wild type (WT) and TTP^-/- macrophages. Also, the rate of decay of PLCβ-2 mRNA in LPS-treated macrophages following transcriptional blockade was similar in WT and TTP^-/- macrophages, clearly indicating that TTP is not involved in LPS-mediated destabilization of PLCβ-2 mRNA in macrophages.

Corylin protects LPS-induced sepsis and attenuates LPS-induced inflammatory response

Corylin is a main compound isolated from Psoralea corylifolia L. (Fabaceae). A variety of pharmacological effects such as antioxidant, anti-proliferation, and anti-inflammatory properties of corylin have been reported. Nevertheless, the effect of corylin in microbial infection and sepsis remains unclear. In the present study, we investigated the anti-inflammatory effects of corylin. Our experimental results demonstrated that corylin inhibited the production of TNF-α, IL-6 and NO by both LPS-activated RAW 264.7 cells and LPS-activated murine peritoneal macrophages. Moreover, corylin suppressed the expression levels of iNOS and COX-2, reduced the production of PGE₂ and HMGB1, blocked the translocation of HMGB1 from the nucleus to cytosol, and decreased the phosphorylation of MAPKs in LPS-activated RAW 264.7 cells as well as suppressed the activity of NF-κB in LPS-activated J-Blue cells. In addition, the administration of corylin reduced the production of NO and TNF-α, decreased LPS-induced liver damage markers (AST and ALT) and kidney damage markers (BUN and CRE), attenuated infiltration of inflammatory cells and tissue damage of lung, liver and kidney, and enhanced the survival rate of LPS-challenged mice. Taken together, these results show the anti-inflammatory properties of corylin on LPS-induced inflammation and sepsis. Corylin could potentially be a novel anti-inflammatory and immunosuppressive drug candidate in the treatment of sepsis and septic shock.

Doxorubicin inhibits muscle inflammation after eccentric exercise

BACKGROUND

Doxorubicin, a widely used anti-tumour drug, is known to cause muscle loss in cancer patients.

METHODS

Following an acute dose of doxorubicin injection (2.5 mg/kg per body weight), we examined macrophage distribution in rat soleus muscle challenged by eccentric exercise (downhill running). Long-term doxorubicin treatment (one injection every 3 days) on muscle mass and survival were also determined.

RESULTS

Under non-exercised condition, increased tumour necrosis factor (TNF)-alpha mRNA and decreased IL-10 mRNA were observed in soleus muscle of doxorubicin-treated rats, compared with saline-treated control rats. However, increases in inflammation score (leukocyte infiltration), nitrotyrosine level, and M1 macrophage (CD68⁺ ) invasion in exercised soleus muscle were absent in doxorubicin-treated rats, whereas increased M2 macrophage (CD163⁺ ) localization in exercised muscle was less affected by doxorubicin. Despites coenzyme Q (Q10) supplementation significantly elevated TNF-alpha mRNA, nitrotyrosine, and anti-oxidant gamma-glutamylcysteine synthetase (GCS) levels in non-exercised soleus muscle, these pro-inflammatory responses were also abolished in doxorubicin-treated rats. Results from long-term doxorubicin treatment show a significant muscle loss followed by an accelerated death, which cannot be reversed by Q10 supplementation.

CONCLUSIONS

(i) Doxorubicin impairs inflammation mechanism by depleting M1 macrophage in exercised skeletal muscle; (ii) Muscle loss and accelerated death during prolonged doxorubicin treatment cannot be reversed by Q10 supplementation.

Pathophysiology of Pediatric Multiple Organ Dysfunction Syndrome

OBJECTIVE

To describe the pathophysiology associated with multiple organ dysfunction syndrome in children.

DATA SOURCES

Literature review, research data, and expert opinion.

STUDY SELECTION

Not applicable.

DATA EXTRACTION

Moderated by an experienced expert from the field, pathophysiologic processes associated with multiple organ dysfunction syndrome in children were described, discussed, and debated with a focus on identifying knowledge gaps and research priorities.

DATA SYNTHESIS

Summary of presentations and discussion supported and supplemented by relevant literature.

CONCLUSIONS

Experiment modeling suggests that persistent macrophage activation may be a pathophysiologic basis for multiple organ dysfunction syndrome. Children with multiple organ dysfunction syndrome have 1) reduced cytochrome P450 metabolism inversely proportional to inflammation; 2) increased circulating damage-associated molecular pattern molecules from injured tissues; 3) increased circulating pathogen-associated molecular pattern molecules from infection or endogenous microbiome; and 4) cytokine-driven epithelial, endothelial, mitochondrial, and immune cell dysfunction. Cytochrome P450s metabolize endogenous compounds and xenobiotics, many of which ameliorate inflammation, whereas damage-associated molecular pattern molecules and pathogen-associated molecular pattern molecules alone and together amplify the cytokine production leading to the inflammatory multiple organ dysfunction syndrome response. Genetic and environmental factors can impede inflammation resolution in children with a spectrum of multiple organ dysfunction syndrome pathobiology phenotypes. Thrombocytopenia-associated multiple organ dysfunction syndrome patients have extensive endothelial activation and thrombotic microangiopathy with associated oligogenic deficiencies in inhibitory complement and a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13. Sequential multiple organ dysfunction syndrome patients have soluble Fas ligand-Fas-mediated hepatic failure with associated oligogenic deficiencies in perforin and granzyme signaling. Immunoparalysis-associated multiple organ dysfunction syndrome patients have impaired ability to resolve infection and have associated environmental causes of lymphocyte apoptosis. These inflammation phenotypes can lead to macrophage activation syndrome. Resolution of multiple organ dysfunction syndrome requires elimination of the source of inflammation. Full recovery of organ functions is noted 6-18 weeks later when epithelial, endothelial, mitochondrial, and immune cell regeneration and reprogramming is completed.

Changes in protein expression after treatment with Ancylostoma caninum excretory/secretory products in a mouse model of colitis

Different reports have highlighted the potential use of helminths and their secretions in the treatment of inflammatory bowel disease (IBD) conditions; however, no reports have investigated their effects at a proteome level. Herein, we characterise the protein expression changes that occur in lamina propria (LP) and the intestinal epithelial cells (IEC) of mice with dextran sulfate sodium (DSS)-induced colitis treated with Ancylostoma caninum excretory/secretory (ES) products using a quantitative proteomic approach. We have shown how parasite products can significantly alter the expression of proteins involved in immune responses, cell death and with an antioxidant activity. Interestingly, significant changes in the expression levels of different mucins were observed in this study. MUC13, a mucin implicated in gastrointestinal homeostasis, was upregulated in the LP of mice with DSS-induced colitis treated with ES, while MUC2, a major component of mucus, was upregulated in the IEC. In addition, A. caninum proteins have an important effect on proteins with antioxidant functions and proteins involved in intestinal homeostasis and tissue integrity and regeneration. Understanding how parasites can ameliorate IBD pathogenesis can help us design novel treatments for autoimmune diseases.

Contributions of transferrin to acute inflammation in the goldfish, C. auratus

Transferrin is an evolutionary conserved protein that in addition to having a critical role in iron transport also has been shown to have a crucial role in host defence, by depriving iron from invading pathogens. Recently cleaved transferrin products was shown to activate macrophages in vitro. We now use an in vivo model of self-resolving peritonitis in goldfish, coupled with gene expression and protein analysis to evaluate the contributions of cleaved transferrin to acute inflammation. We show, for the first time, that cleaved transferrin products are produced in vivo early during an acute inflammatory response. These cleaved transferrin fragments were produced during pathogen-induced, but not sterile, inflammation. Both macrophages and neutrophils were able to contribute to transferrin cleavage. However, only macrophages contributed to this innate process through inducible expression of transferrin. The appearance of transferrin cleavage products in vivo correlated with the influx of leukocytes but did not necessarily correlate the induction of robust respiratory burst and nitric oxide responses. Overall, this study adds to a growing body of work highlighting the role of transferrin as an immune regulator during acute inflammation. Given the significant conservation of this and related molecules, these findings have potentially broad implications for host defences and inflammation control across evolution.

Nitric oxide-activatable gold nanoparticles for specific targeting and photo-thermal ablation of macrophages

Nitric oxide-activatable gold nanoparticles can be utilized as a useful NO sensing tool and a photo-thermal agent for specific inflammation-associated macrophages.

Testing the biological embedding hypothesis: Is early life adversity associated with a later proinflammatory phenotype?

Accumulating evidence suggests that the experience of early life adversity is a risk factor for a range of poor outcomes across development, including poor physical health in adulthood. The biological embedding model of early adversity (Miller, Chen, & Parker, 2011) suggests that early adversity might become embedded within immune cells known as monocytes/macrophages, programming them to be overly aggressive to environmental stimuli and insensitive to inhibitory signals, creating a "proinflammatory phenotype" that increases vulnerability to chronic diseases across the life span. We tested this hypothesis in the present study. Adolescent girls (n = 147) had blood drawn every 6 months across a 2.5-year period. To assess inflammatory responses to challenge, their monocytes were stimulated in vitro with a bacterial product, and production of the cytokine interleukin-6 was quantified. Hydrocortisone was added to cultures to assess the cells' sensitivity to glucocorticoids' anti-inflammatory signal. Using cluster analyses, we found that early life adversity was associated with greater odds of displaying a proinflammatory phenotype characterized by relatively larger interleukin-6 responses and relatively less sensitivity to glucocorticoids. In contrast, ongoing social stress was not associated with increasing odds of being categorized in the proinflammatory cluster. These findings suggest that early life adversity increases the probability of developing a proinflammatory phenotype, which, if sustained, could forecast risk for health problems later in life.

Effects of xenoestrogens in human M1 and M2 macrophage migration, cytokine release, and estrogen-related signaling pathways

Bisphenol A (BPA), bis(2-ethylhexyl)phthalate (DEHP) and di(n-butyl)phthalate (DBP) are environmental estrogens that have been associated with a wide range of adverse health outcomes for which inflammation has also been hypothesized as a potentially involved mechanism and where macrophages play a central role. This study was carried out to evaluate if xenoestrogen (XE) treatment of classically (M1) or alternatively (M2) activated macrophages could affect their behavior. For this purpose, human peripheral blood monocyte-derived macrophages either unstimulated or activated with lipopolysaccharide (100 ng/mL, M1) or with interleukin (IL) 4 (15 ng/mL, M2) were treated with 17β-estradiol (E₂ ), BPA, DEHP and DBP alone or in combination with selective ERα or ERβ antagonists. Migratory capability, cytokine release, and estrogen-associated signaling pathways were evaluated to assess macrophage function. All tested XEs had a tendency to stimulate M2 migration, an effect that followed the same direction than E₂ . Moreover, all XEs significantly induced IL10 in M1 and decreased IL6 and globally decreased IL10, IL6, TNFα, and IL1β release by M2 macrophages. However, DEHP and DBP significantly increased IL1β release in M1 and M2 macrophages, respectively. Some of the effects described above were shown to be mediated by either ERα or ERβ and were simultaneous to modulation of NF-κB, AP1, JNK, or ERK signaling pathways. We provide new evidence of the effect of XE on macrophage behavior and their mechanisms with relevance to the understanding of the action of environmental chemicals on the immune system and inflammation-associated diseases. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1496-1509, 2016.

Sakuranetin Inhibits Inflammatory Enzyme, Cytokine, and Costimulatory Molecule Expression in Macrophages through Modulation of JNK, p38, and STAT1

Sakuranetin is flavonoid phytoalexin that serves as a plant antibiotic and exists in Prunus and several other plant species. Recently, we identified the anti-inflammatory effect of Prunus yedoensis and found that there were few studies on the potential anti-inflammatory activity of sakuranetin, one of the main constituents of Prunus yedoensis. Here, we isolated peritoneal macrophages from thioglycollate-injected mice and examined whether sakuranetin affected the response of the macrophages in response to lipopolysaccharide (LPS) plus interferon- (IFN-) γ or LPS only. Sakuranetin suppressed the synthesis of iNOS and COX2 in LPS/IFN-γ stimulated cells and the secretion of TNF-α, IL-6, and IL-12 in LPS stimulated cells. The surface expression of the costimulatory molecules, CD86 and CD40, was also decreased. Among the LPS-induced signaling molecules, STAT1, JNK, and p38 phosphorylation was attenuated. These findings are evidence that sakuranetin acts as anti-inflammatory flavonoid and further study is required to evaluate its in vivo efficacy.

The impact of hypoxia on tumor-associated macrophages

The role of tumor-associated macrophages (TAMs) in cancer is often correlated with poor prognosis, even though this statement should be interpreted with care, as the effects of macrophages primarily depend on their localization within the tumor. This versatile cell type orchestrates a broad spectrum of biological functions and exerts very complex and even opposing functions on cell death, immune stimulation or suppression, and angiogenesis, resulting in an overall pro- or antitumoral effect. We are only beginning to understand the environmental cues that contribute to transient retention of macrophages in a specific phenotype. It has become clear that hypoxia shapes and induces specific macrophage phenotypes that serve tumor malignancy, as hypoxia promotes immune evasion, angiogenesis, tumor cell survival, and metastatic dissemination. Additionally, TAMs in the hypoxic niches within the tumor are known to mediate resistance to several anticancer treatments and to promote cancer relapse. Thus, a careful characterization and understanding of this macrophage differentiation state is needed in order to efficiently tailor cancer therapy.

Cardiac Tissue Injury and Remodeling Is Dependent Upon MR Regulation of Activation Pathways in Cardiac Tissue Macrophages

Macrophage mineralocorticoid receptor (MR) signaling is an important mediator of cardiac tissue inflammation and fibrosis. The goal of the present study was to determine the cellular mechanisms of MR signaling in macrophages that promote cardiac tissue injury and remodeling. We sought to identify specific markers of MR signaling in isolated tissue macrophages (cardiac, aortic) vs splenic mononuclear cells from wild-type and myeloid MR-null mice given vehicle/salt or deoxycorticosterone (DOC)/salt for 8 weeks. Cardiac tissue fibrosis in response to 8 weeks of DOC/salt treatment was found in the hearts from wild-type but not myeloid MR-null mice. This was associated with an increased expression of the profibrotic markers TGF-β1 and matrix metalloproteinase-12 and type 1 inflammatory markers TNFα and chemokine (C-X-C motif) ligand-9 in cardiac macrophages. Differential expression of immunomodulatory M2-like markers (eg, arginase-1, macrophage scavenger receptor 1) was dependent on the tissue location of wild-type and MR-null macrophages. Finally, intact MR signaling is required for the phosphorylation of c-Jun NH2-terminal kinase in response to a proinflammatory stimulus in bone marrow monocytes/macrophages in culture. These data suggest that the activation of the c-Jun NH2-terminal kinase pathway in macrophages after a tissue injury and inflammatory stimuli in the DOC/salt model is MR dependent and regulates the transcription of downstream profibrotic factors, which may represent potential therapeutic targets in heart failure patients.

Liver Necrosis and Lethal Systemic Inflammation in a Murine Model of Rickettsia typhi Infection: Role of Neutrophils, Macrophages and NK Cells

Rickettsia (R.) typhi is the causative agent of endemic typhus, an emerging febrile disease that is associated with complications such as pneumonia, encephalitis and liver dysfunction. To elucidate how innate immune mechanisms contribute to defense and pathology we here analyzed R. typhi infection of CB17 SCID mice that are congenic to BALB/c mice but lack adaptive immunity. CB17 SCID mice succumbed to R. typhi infection within 21 days and showed high bacterial load in spleen, brain, lung, and liver. Most evident pathological changes in R. typhi-infected CB17 SCID mice were massive liver necrosis and splenomegaly due to the disproportionate accumulation of neutrophils and macrophages (MΦ). Both neutrophils and MΦ infiltrated the liver and harbored R. typhi. Both cell populations expressed iNOS and produced reactive oxygen species (ROS) and, thus, exhibited an inflammatory and bactericidal phenotype. Surprisingly, depletion of neutrophils completely prevented liver necrosis but neither altered bacterial load nor protected CB17 SCID mice from death. Furthermore, the absence of neutrophils had no impact on the overwhelming systemic inflammatory response in these mice. This response was predominantly driven by activated MΦ and NK cells both of which expressed IFNγ and is considered as the reason of death. Finally, we observed that iNOS expression by MΦ and neutrophils did not correlate with R. typhi uptake in vivo. Moreover, we demonstrate that MΦ hardly respond to R. typhi in vitro. These findings indicate that R. typhi enters MΦ and also neutrophils unrecognized and that activation of these cells is mediated by other mechanisms in the context of tissue damage in vivo.

Overexpression of HDAC6 induces pro-inflammatory responses by regulating ROS-MAPK-NF-κB/AP-1 signaling pathways in macrophages

Although histone deacetylase 6 (HDAC6) has been implicated in inflammatory diseases, direct involvement and its action mechanism of HDAC6 in the transcriptional regulation of pro-inflammatory genes have been unclear. In this study, we investigated the possible role of HDAC6 in the expression of pro-inflammatory mediators, indicator of macrophage activation, in RAW 264.7 cells and primary mouse macrophages. HDAC6 overexpression significantly enhanced expression of pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, with concomitant reduction in acetylated α-tubulin. HDAC6 overexpression significantly induced ROS generation via upregulation of NADPH oxidase expression and activity. Inhibition of ROS generation by N-acetyl cysteine, diphenyl iodonium and apocynin suppressed HDAC6-induced pro-inflammatory cytokines. An HDAC6 enzymatic inhibitor significantly inhibited ROS generation and expression of HDAC6-induced pro-inflammatory mediators, indicating the requirement of HDAC6 enzymatic activity for induction of pro-inflammatory cytokines. In addition, HDAC6 overexpression increased activation of MAPK species including ERK, JNK, and p38. Furthermore, HDAC6 overexpression resulted in activation of the NF-κB and AP-1 signaling pathways. Overall, our results provide the first evidence that HDAC6 is capable of inducing expression of pro-inflammatory genes by regulating the ROS-MAPK-NF-κB/AP-1 pathways and serves as a molecular target for inflammation.

Emerging roles of protein mannosylation in inflammation and infection

Proteins are frequently modified by complex carbohydrates (glycans) that play central roles in maintaining the structural and functional integrity of cells and tissues in humans and lower organisms. Mannose forms an essential building block of protein glycosylation, and its functional involvement as components of larger and diverse α-mannosidic glycoepitopes in important intra- and intercellular glycoimmunological processes is gaining recognition. With a focus on the mannose-rich asparagine (N-linked) glycosylation type, this review summarises the increasing volume of literature covering human and non-human protein mannosylation, including their structures, biosynthesis and spatiotemporal expression. The review also covers their known interactions with specialised host and microbial mannose-recognising C-type lectin receptors (mrCLRs) and antibodies (mrAbs) during inflammation and pathogen infection. Advances in molecular mapping technologies have recently revealed novel immuno-centric mannose-terminating truncated N-glycans, termed paucimannosylation, on human proteins. The cellular presentation of α-mannosidic glycoepitopes on N-glycoproteins appears tightly regulated; α-mannose determinants are relative rare glycoepitopes in physiological extracellular environments, but may be actively secreted or leaked from cells to transmit potent signals when required. Simultaneously, our understanding of the molecular basis on the recognition of mannosidic epitopes by mrCLRs including DC-SIGN, mannose receptor, mannose binding lectin and mrAb is rapidly advancing, together with the functional implications of these interactions in facilitating an effective immune response during physiological and pathophysiological conditions. Ultimately, deciphering these complex mannose-based receptor-ligand interactions at the detailed molecular level will significantly advance our understanding of immunological disorders and infectious diseases, promoting the development of future therapeutics to improve patient clinical outcomes.

Anti-inflammatory effects of proanthocyanidin-rich red rice extract via suppression of MAPK, AP-1 and NF-κB pathways in Raw 264.7 macrophages

BACKGROUND/OBJECTIVES

Several pharmacological properties of red rice extract have been reported including anti-oxidant, anti-tumor, and reduced cancer cell invasion. This study was conducted to evaluate the anti-inflammatory effects of red rice extract on the production of inflammatory mediators in lipopolysaccharide (LPS)-induced Raw 264.7 macrophages.

MATERIALS/METHODS

Pro-inflammatory cytokines including tumor necrosis factor-α and interleukin-6 were determined by ELISA and cyclooxygenase-2 and inducible nitric oxide synthase expression was evaluated using western blot analysis. In addition, the signaling pathway controlling the inflammatory cascade such as nuclear factor kappa B (NF-κB), activator proteins-1 (AP-1), and mitogen-activated protein kinase (MAPK) was determined.

RESULTS

Our results showed that red rice polar extract fraction (RR-P), but not non-polar extract fraction, inhibited interleukin-6, tumor necrosis factor-α, and nitric oxide production in LPS-induced Raw 264.7 cells. RR-P also reduced the expression of inflammatory enzymes, inducible nitric oxide synthase, and cyclooxygenase-2. In addition, activation of AP-1 and NF-κB transcription factor in the nucleus was abrogated by RR-P. RR-P inhibited the phosphorylation of extracellular signaling-regulated kinase 1/2, c-Jun NH2-terminal kinase, and p38 MAPK signaling responsible for the expression of inflammatory mediators in LPS-stimulated Raw 264.7 cells. Based on chemical analysis, high amounts of proanthocyanidin and catechins were detected in the RR-P fraction. However, only proanthocyanidin reduced NF-κB and AP-1 activation in LPS-activated Raw 264.7 cells.

CONCLUSION

These observations suggest that the anti-inflammatory properties of RR-P may stem from the inhibition of pro-inflammatory mediators via suppression of the AP-1, NF-κB, and MAPKs pathways.

High-Content Quantification of Single-Cell Immune Dynamics

Cells receive time-varying signals from the environment and generate functional responses by secreting their own signaling molecules. Characterizing dynamic input-output relationships in single cells is crucial for understanding and modeling cellular systems. We developed an automated microfluidic system that delivers precisely defined dynamical inputs to individual living cells and simultaneously measures key immune parameters dynamically. Our system combines nanoliter immunoassays, microfluidic input generation, and time-lapse microscopy, enabling study of previously untestable aspects of immunity by measuring time-dependent cytokine secretion and transcription factor activity from single cells stimulated with dynamic inflammatory inputs. Employing this system to analyze macrophage signal processing under pathogen inputs, we found that the dynamics of TNF secretion are highly heterogeneous and surprisingly uncorrelated with the dynamics of NF-κB, the transcription factor controlling TNF production. Computational modeling of the LPS/TLR4 pathway shows that post-transcriptional regulation by TRIF is a key determinant of noisy and uncorrelated TNF secretion dynamics in single macrophages.

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Dynamic stimulation of single immune cells with a versatile microfluidic device

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Coupled longitudinal measurements of NF-κB localization and TNF secretion on the same cell

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Single-cell harvesting, staining, and mRNA quantification on the same device

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High-content dataset, and modeling of TRIF-based noise in TNF secretion

Divergent impact of Toll-like receptor 2 deficiency on repair mechanisms in healthy muscle versus Duchenne muscular dystrophy

Injury to skeletal muscle, whether acute or chronic, triggers macrophage-mediated innate immunity in a manner which can be either beneficial or harmful for subsequent repair. Endogenous ligands for Toll-like receptor 2 (TLR2) are released by damaged tissues and might play an important role in activating the innate immune system following muscle injury. To test this hypothesis, we compared macrophage behaviour and muscle repair mechanisms in mice lacking TLR2 under conditions of either acute (cardiotoxin-induced) or chronic (mdx mouse genetic model of Duchenne muscular dystrophy; DMD) muscle damage. In previously healthy muscle subjected to acute damage, TLR2 deficiency reduced macrophage numbers in the muscle post-injury but did not alter the expression pattern of the prototypical macrophage polarization markers iNOS and CD206. In addition, there was abnormal persistence of necrotic fibres and impaired regeneration in TLR2-/- muscles after acute injury. In contrast, TLR2 ablation in chronically diseased muscles of mdx mice not only resulted in significantly reduced macrophage numbers but additionally modified their phenotype by shifting from inflammatory (iNOS(pos) CD206(neg) ) to more anti-inflammatory (iNOS(neg) CD206(pos) ) characteristics. This decrease in macrophage-mediated inflammation was associated with ameliorated muscle histopathology and improved force-generating capacity of the dystrophic muscle. Our results suggest that the role of TLR2 in macrophage function and skeletal muscle repair depends greatly upon the muscle injury context, and raise the possibility that inhibition of TLR2 could serve as a useful therapeutic measure in DMD.

Changes in macrophage function modulated by the lipid environment

Macrophages (Mφs) play a critical role in the defense against pathogens, orchestrating the inflammatory response during injury and maintaining tissue homeostasis. During these processes, macrophages encounter a variety of environmental conditions that are likely to change their gene expression pattern, which modulates their function. In this study, we found that murine Mφs displayed two different subpopulations characterized by differences in morphologies, expression of surface markers and phagocytic capacity under non-stimulated conditions. These two subpopulations could be recapitulated by changes in the culture conditions. Thus, Mφs grown in suspension in the presence of serum were highly phagocytic, whereas subtraction of serum resulted in rapid attachment and reduced phagocytic activity. The difference in phagocytosis between these subpopulations was correlated with the expression levels of FcγR. These two cell subpopulations also differed in their responses to LPS and the expression of surface markers, including CD14, CD86, scavenger receptor A1, TLR4 and low-density lipoprotein receptor. Moreover, we found that the lipid/cholesterol content in the culture medium mediated the differences between these two cell subpopulations. Thus, we described a mechanism that modulates Mφ function depending on the exposure to lipids within their surrounding microenvironment.

RAGE-mediated inflammation in patients with septic shock

BACKGROUND

The receptor for advanced glycation end-products (RAGE)-pathway is described to be a crucial component of the innate immune response in sepsis. The aims of the present study were, therefore, to delineate the kinetics of membrane-bound RAGE expression, to quantify its soluble isoforms, and to determine the extent of metabolic (e.g., AGE-CML) as well as immunologic (e.g., S100A8/A9) ligands in different inflammatory settings in humans.

MATERIALS AND METHODS

The presented data result from secondary analyses of an observational clinical pilot study, including patients with septic shock (n = 60), postoperative controls (n = 30), and healthy volunteers (n = 30). Surface-bound expression of RAGE by peripheral blood leukocytes was determined by flow cytometry. In addition, plasma levels of sRAGE, esRAGE, AGE-CML, S100A8/A9, S100A8/A9-CML, RBP, RBP-CML, HSA-CML, HMBG-1, and ß-Amyloid were measured using ELISA.

RESULTS

In patients with septic shock, RAGE expression was significantly increased in comparison to both control groups, which was paralleled by a significant increase in sRAGE plasma levels. Formation of AGE-CML was shown to be dependent on the availability of the unmodified protein. However, the total amount of AGE-CML did not differ significantly between septic patients and healthy volunteers at early stages or was even lower in patients with sepsis at later stages. In contrast, immunologic ligands (e.g., S100A8/A9) were shown to be significantly elevated in septic patients within the entire study period.

CONCLUSIONS

Activation of the RAGE-pathway was shown to be of relevance in patients with septic shock, mainly driven by an increase in immunologic (e.g., S100A8/A9) rather than metabolic ligands (e.g., CML-derived AGE-formation).

Anti-inflammatory potential of total saponins derived from the roots of Panax ginseng in lipopolysaccharide-activated RAW 264.7 macrophages

Ginseng, the root of Panax ginseng C.A. Meyer (Araliaceae), is a widely known traditional medicine that has been utilized throughout Asia for several thousand years. Ginseng saponins exert various important pharmacological effects regarding the control of a number of diseases. The aim of the present study was to identify the anti-inflammatory effects of total saponins extracted from ginseng (TSG) on lipopolysaccharide (LPS)-stimulated mouse RAW 264.7 macrophages. The inhibitory effects of TSG on LPS-induced nitric oxide (NO) production and LPS-induced tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) protein expression were determined by measuring the levels of nitrite and enzyme-linked immunosorbent assays, respectively. Furthermore, the effects of TSG on the mRNA expression levels and localizations of inducible NO synthase (iNOS), IL-1β and TNF-α, and their upstream signaling proteins, including nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs), were investigated by reverse transcription-polymerase chain reaction and western blotting, respectively. Following stimulation with LPS, elevated levels of NO production were detected in RAW 264.7 cells; however, TSG pretreatment significantly inhibited the production of NO (P<0.05), by suppressing the expression of iNOS. In addition, LPS-stimulated TNF-α and IL-1β production was significantly reduced by TSG (P<0.05). In the LPS-stimulated RAW 264.7 cells, NF-κB was translocated from the cytosol to the nucleus, whilst TSG pretreatment induced the sequestration of NF-κB in the cytosol by inhibiting inhibitor of κB degradation. TSG also contributed to downregulation of MAPKs in LPS-stimulated RAW 264.7 cells. These results suggested that TSG may exert anti-inflammatory activity, and that TSG may be considered a potential therapeutic for the treatment of inflammatory diseases associated with macrophage activation.

Genome-wide association study reveals novel loci for litter size and its variability in a Large White pig population

Background

In many traits, not only individual trait levels are under genetic control, but also the variation around that level. In other words, genotypes do not only differ in mean, but also in (residual) variation around the genotypic mean. New statistical methods facilitate gaining knowledge on the genetic architecture of complex traits such as phenotypic variability. Here we study litter size (total number born) and its variation in a Large White pig population using a Double Hierarchical Generalized Linear model, and perform a genome-wide association study using a Bayesian method.

Results

In total, 10 significant single nucleotide polymorphisms (SNPs) were detected for total number born (TNB) and 9 SNPs for variability of TNB (varTNB). Those SNPs explained 0.83 % of genetic variance in TNB and 1.44 % in varTNB. The most significant SNP for TNB was detected on Sus scrofa chromosome (SSC) 11. A possible candidate gene for TNB is ENOX1, which is involved in cell growth and survival. On SSC7, two possible candidate genes for varTNB are located. The first gene is coding a swine heat shock protein 90 (HSPCB = Hsp90), which is a well-studied gene stabilizing morphological traits in Drosophila and Arabidopsis. The second gene is VEGFA, which is activated in angiogenesis and vasculogenesis in the fetus. Furthermore, the genetic correlation between additive genetic effects on TNB and on its variation was 0.49. This indicates that the current selection to increase TNB will also increase the varTNB.

Conclusions

To the best of our knowledge, this is the first study reporting SNPs associated with variation of a trait in pigs. Detected genomic regions associated with varTNB can be used in genomic selection to decrease varTNB, which is highly desirable to avoid very small or very large litters in pigs. However, the percentage of variance explained by those regions was small. The SNPs detected in this study can be used as indication for regions in the Sus scrofa genome involved in maintaining low variability of litter size, but further studies are needed to identify the causative loci.

Extracellular Histones Induce Chemokine Production in Whole Blood Ex Vivo and Leukocyte Recruitment In Vivo

The innate immune system relies to a great deal on the interaction of pattern recognition receptors with pathogen- or damage-associated molecular pattern molecules. Extracellular histones belong to the latter group and their release has been described to contribute to the induction of systemic inflammatory reactions. However, little is known about their functions in the early immune response to an invading pathogen. Here we show that extracellular histones specifically target monocytes in human blood and this evokes the mobilization of the chemotactic chemokines CXCL9 and CXCL10 from these cells. The chemokine induction involves the toll-like receptor 4/myeloid differentiation factor 2 complex on monocytes, and is under the control of interferon-γ. Consequently, subcutaneous challenge with extracellular histones results in elevated levels of CXCL10 in a murine air pouch model and an influx of leukocytes to the site of injection in a TLR4 dependent manner. When analyzing tissue biopsies from patients with necrotizing fasciitis caused by Streptococcus pyogenes, extracellular histone H4 and CXCL10 are immunostained in necrotic, but not healthy tissue. Collectively, these results show for the first time that extracellular histones have an important function as chemoattractants as their local release triggers the recruitment of immune cells to the site of infection.

The detrimental effects of extracellular histones under pathological conditions have lately attracted considerable attention. However, little is known about their functions as damage-associated molecular pattern molecules. Our study shows for the first time that extracellular histones trigger the induction of chemotactic chemokines from monocytes. As this interaction is dependent on a pattern recognition receptor, namely toll-like receptor 4, our data indeed point to an important role of extracellular histones in danger signaling. Notably, CXCL9 and CXCL10 are chemoattractants, and the recruitment of immune cells to the site of histone injection in a subcutaneous mouse model supports the concept that low levels of extracellular histones constitute a part of the host response.

Temporal cardiac remodeling post-myocardial infarction: dynamics and prognostic implications in personalized medicine

Despite dramatic improvements in short-term mortality rates following myocardial infarction (MI), long-term survival for MI patients who progress to heart failure remains poor. MI occurs when the left ventricle (LV) is deprived of oxygen for a sufficient period of time to induce irreversible necrosis of the myocardium. The LV response to MI involves significant tissue, cellular, and molecular level modifications, as well as substantial hemodynamic changes that feedback negatively to amplify the response. Inflammation to remove necrotic myocytes and fibroblast activation to form a scar are key wound healing responses that are highly variable across individuals. Few biomarkers of early remodeling stages are currently clinically adopted. The discovery of underlying pathophysiological mechanisms and associated novel biomarkers has the potential of improving prognostic capability and therapeutic monitoring. Combining these biomarkers with other prominent ones could constitute a powerful diagnostic and prognostic tool that directly reflects the pathophysiological remodeling of the LV. Understanding temporal remodeling at the tissue, cellular, and molecular level and its link to a well-defined set of biomarkers at early stages post-MI is a prerequisite for improving personalized care and devising more successful therapeutic interventions. Here we summarize the integral mechanisms that occur during early cardiac remodeling in the post-MI setting and highlight the most prominent biomarkers for assessing disease progression.

Molecular and cellular mechanisms that initiate pain and itch

Somatosensory neurons mediate our sense of touch. They are critically involved in transducing pain and itch sensations under physiological and pathological conditions, along with other skin-resident cells. Tissue damage and inflammation can produce a localized or systemic sensitization of our senses of pain and itch, which can facilitate our detection of threats in the environment. Although acute pain and itch protect us from further damage, persistent pain and itch are debilitating. Recent exciting discoveries have significantly advanced our knowledge of the roles of membrane-bound G protein-coupled receptors and ion channels in the encoding of information leading to pain and itch sensations. This review focuses on molecular and cellular events that are important in early stages of the biological processing that culminates in our senses of pain and itch.

Urolithins, gut microbiota-derived metabolites of ellagitannins, inhibit LPS-induced inflammation in RAW 264.7 murine macrophages

SCOPE

Ellagitannin-rich food products and medicinal plant materials were shown to have beneficial effects toward intestinal inflammation. Due to the questionable bioavailability of ellagitannins their gut microbiota metabolites-urolithins have come to be regarded as potential factors responsible for biological activities observed in vivo. The aim of the study was to determine the influence of the three most abundant bioavailable ellagitannin gut microbiota metabolites-urolithins A, B, and C on inflammatory responses in RAW 264.7 murine macrophages, which are involved in the pathogenesis of intestine inflammation.

METHODS AND RESULTS

Urolithins A, B, and C decreased NO production via inhibition of the iNOS protein and mRNA expression. They decreased the expression of IL-1β, TNF-α, and IL-6 mRNA in LPS challenged RAW 264.7 murine macrophages. A clear inhibition of NF-κB p65 nuclear translocation and p50 DNA-binding activity was associated with the observed anti-inflammatory activities of urolithins. Among the tested compounds urolithin A had the strongest anti-inflammatory activity.

CONCLUSION

The anti-inflammatory effects of urolithins at concentrations that are physiologically relevant for gut tissues (≥40 μM), as revealed in this study, support the data from in vivo studies showing the beneficial effects of ellagitannin-rich products toward intestinal inflammation.

Upregulated IL-1β in dysferlin-deficient muscle attenuates regeneration by blunting the response to pro-inflammatory macrophages

BACKGROUND

Loss-of-function mutations in the dysferlin gene (DYSF) result in a family of muscle disorders known collectively as the dysferlinopathies. Dysferlin-deficient muscle is characterized by inflammatory foci and macrophage infiltration with subsequent decline in muscle function. Whereas macrophages function to remove necrotic tissue in acute injury, their prevalence in chronic myopathy is thought to inhibit resolution of muscle regeneration. Two major classes of macrophages, classical (M1) and alternative (M2a), play distinct roles during the acute injury process. However, their individual roles in chronic myopathy remain unclear and were explored in this study.

METHODS

To test the roles of the two macrophage phenotypes on regeneration in dysferlin-deficient muscle, we developed an in vitro co-culture model of macrophages and muscle cells. We assayed the co-cultures using ELISA and cytokine arrays to identify secreted factors and performed transcriptome analysis of molecular networks induced in the myoblasts.

RESULTS

Dysferlin-deficient muscle contained an excess of M1 macrophage markers, compared with WT, and regenerated poorly in response to toxin injury. Co-culturing macrophages with muscle cells showed that M1 macrophages inhibit muscle regeneration whereas M2a macrophages promote it, especially in dysferlin-deficient muscle cells. Examination of soluble factors released in the co-cultures and transcriptome analysis implicated two soluble factors in mediating the effects: IL-1β and IL-4, which during acute injury are secreted from M1 and M2a macrophages, respectively. To test the roles of these two factors in dysferlin-deficient muscle, myoblasts were treated with IL-4, which improved muscle differentiation, or IL-1β, which inhibited it. Importantly, blockade of IL-1β signaling significantly improved differentiation of dysferlin-deficient cells.

CONCLUSIONS

We propose that the inhibitory effects of M1 macrophages on myogenesis are mediated by IL-1β signals and suppression of the M1-mediated immune response may improve muscle regeneration in dysferlin deficiency. Our studies identify a potential therapeutic approach to promote muscle regeneration in dystrophic muscle.

Inflammation and Cell Death in Age-Related Macular Degeneration: An Immunopathological and Ultrastructural Model

The etiology of Age-related Macular Degeneration (AMD) remains elusive despite the characterization of many factors contributing to the disease in its late-stage phenotypes. AMD features an immune system in flux, as shown by changes in macrophage polarization with age, expression of cytokines and complement, microglial accumulation with age, etc. These point to an allostatic overload, possibly due to a breakdown in self vs. non-self when endogenous compounds and structures acquire the appearance of non-self over time. The result is inflammation and inflammation-mediated cell death. While it is clear that these processes ultimately result in degeneration of retinal pigment epithelium and photoreceptor, the prevalent type of cell death contributing to the various phenotypes is unknown. Both molecular studies as well as ultrastructural pathology suggest pyroptosis, and perhaps necroptosis, are the predominant mechanisms of cell death at play, with only minimal evidence for apoptosis. Herein, we attempt to reconcile those factors identified by experimental AMD models and integrate these data with pathology observed under the electron microscope—particularly observations of mitochondrial dysfunction, DNA leakage, autophagy, and cell death.

AKT mediated glycolytic shift regulates autophagy in classically activated macrophages

Autophagy is considered as an innate defense mechanism primarily due to its role in the targeting of intracellular pathogens for lysosomal degradation. Here we report inhibition of autophagy as an adaptive response in classically activated macrophages that helps achieve high cellular ROS production and cell death-another hallmark of innate mechanisms. We show prolonged classical activation of Raw 264.7 macrophages by treating them with IFN-γ and LPS inhibited autophagy. The inhibition of autophagy was dependent on nitric oxide (NO) production which activated the AKT-mTOR signaling, the known negative regulators of autophagy. Autophagy inhibition in these cells was accompanied with a shift to aerobic glycolysis along with a decline in the mitochondrial membrane potential (MOMP). The decline in MOMP coupled with autophagy inhibition led to increased mitochondrial content and considerably elevated cellular ROS, eventually causing cell death. Next, using specific siRNA mediated knockdowns we show AKT was responsible for the glycolytic shift and autophagy inhibition in activated macrophages. Surprisingly, AKT knockdown in activated macrophages also rescued them from cell death. Finally we show that AKT mediated autophagy inhibition in the activated macrophages correlated with the depletion of glucose from the extracellular medium, and glucose supplementation not only rescued autophagy levels and reversed other phenotypes of activated macrophages, but also inhibited cell death. Thus we report here a novel link between AKT mediated glycolytic metabolism and autophagy in the activated macrophages, and provide a possible mechanism for sustained macrophage activation in vivo.

Brief Glutamine Pretreatment Increases Alveolar Macrophage CD163/Heme Oxygenase-1/p38-MAPK Dephosphorylation Pathway and Decreases Capillary Damage but Not Neutrophil Recruitment in IL-1/LPS-Insufflated Rats

Background

Glutamine (GLN) attenuates acute lung injury (ALI) but its effect on alveolar macrophages is unknown. We hypothesized that GLN pretreatment would induce the anti-inflammatory CD163/heme oxygenase (HO)-1/p38-MAPK dephosphorylation pathway in alveolar macrophages and reduce ALI in rats insufflated with interleukin-1 (IL-1) and lipopolysaccharide (LPS).

Methods

Male Sprague-Dawley rats were randomized to the following groups: GLN-IL-1/LPS-, GLN+IL-1/LPS-, GLN-IL-1/LPS+, and GLN+IL-1/LPS+. GLN pretreatment was given via gavage (1g/kg L-alanyl-L-glutamine) daily for 2 days. ALI was subsequently induced by insufflating 50ng IL-1 followed by 5mg/kg E.coli LPS. After 24h, bronchoalveolar lavage (BAL) protein, lactate dehydrogenase (LDH) and neutrophil concentrations were analyzed. BAL alveolar macrophage CD163+ expression, HO-1 and p38-MAPK concentrations were measured, as well as alveolar macrophage tumor necrosis factor (TNF)-α and interleukin (IL)-10 concentrations. Histology and immunofluorescence studies were also performed.

Results

Following IL-1/LPS insufflation, GLN pretreated rats had significantly decreased BAL protein and LDH concentrations, but not BAL neutrophil counts, compared to non-GLN pretreated rats. The number of alveolar macrophages and the number of CD163+ macrophages were significantly increased in GLN pretreated IL-1/LPS-insufflated rats compared to non-GLN pretreated, IL-1/LPS-insufflated rats. GLN pretreatment before IL-1/LPS also significantly increased HO-1 concentrations and dephosphorylated p38-MAPK levels but not cytokine levels in alveolar macrophages. Immunofluorescence localized CD163 and HO-1 in alveolar macrophages.

Conclusion

Short-term GLN pretreatment activates the anti-inflammatory CD163/HO-1/p38-MAPK dephosphorylation pathway of alveolar macrophages and decreases capillary damage but not neutrophil recruitment in IL-1/LPS-insufflated rats.

Cytotoxic and nitric oxide production-inhibitory activities of limonoids and other compounds from the leaves and bark of Melia azedarach

Nine limonoids, 1-9, one apocarotenoid, 11, one alkaloid, 12, and one steroid, 13, from the leaf extract; and one triterpenoid, 10, five steroids, 14-18, and two flavonoids, 19 and 20, from the bark extract of Melia azedarach L. (Chinaberry tree; Meliaceae) were isolated. Among these compounds, three compounds, 4-6, were new, and their structures were established as 3-deacetyl-28-oxosalannolactone, 3-deacetyl-28-oxosalanninolide, and 3-deacetyl-17-defurano-17,28-dioxosalannin, respectively, on the basis of extensive spectroscopic analyses and comparison with literature data. All of the isolated compounds were evaluated for their cytotoxic activities against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK-BR-3) cancer cell lines. 3-Deacetyl-4'-demethyl-28-oxosalannin (3) against HL60 and AZ521 cells, and methyl kulonate (10) against HL60 cells exhibited potent cytotoxicities with IC50 values in the range of 2.8-5.8 μM. In addition, upon evaluation of compounds 1-13 against production of nitric oxide (NO) in mouse macrophage RAW 264.7 cells induced by lipopolysaccharide (LPS), seven, i.e., trichilinin B (1), 4, ohchinin (7), 23-hydroxyohchininolide (8), 21-hydroxyisoohchininolide (9), 10, and methyl indole 3-carboxylate (12), inhibited production of NO with IC50 values in the range of 4.6-87.3 μM with no, or almost no, toxicity to the cells (IC50 93.2-100 μM). Western blot analysis revealed that compound 7 reduced the expression levels of the inducible NO synthase (iNOS) and COX-2 proteins in a concentration-dependent manner. Furthermore, compounds 5, 6, 13, and 18-20 exhibited potent inhibitory effects (IC50 299-381 molar ratio/32 pmol TPA) against Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cell line.

3,4-Dihydroxy-benzohydroxamic acid (Didox) suppresses pro-inflammatory profiles and oxidative stress in TLR4-activated RAW264.7 murine macrophages

Didox (3,4-dihydroxy-benzohydroxamic acid), is a synthetic ribonucleotide reductase (RR) inhibitor derived from polyhydroxy-substituted benzohydroxamic acid, and originally developed as an anti-cancer agent. Some studies indicate that didox may have anti-oxidative stress-like properties, while other studies hint that didox may have anti-inflammatory properties. Using nitric oxide production in response to LPS treatment as a sensitive screening assay for anti-inflammatory compounds, we show that didox is very potent at levels as low as 6.25 μM, with maximal inhibition at 100 μM. A qRT-PCR array was then employed to screen didox for other potential anti-inflammatory and anti-oxidative stress-related properties. Didox was very potent in suppressing the expression of these arrayed mRNA in response to LPS, and in some cases didox alone suppressed expression. Using qRT-PCR as a follow up to the array, we demonstrated that didox suppresses LPS-induced mRNA levels of iNOS, IL-6, IL-1, TNF-α, NF-κβ (p65), and p38-α, after 24h of treatment. Treatment with didox also suppresses the secretion of nitric oxide, IL-6, and IL-10. Furthermore, oxidative stress, as quantified by intracellular ROS levels in response to macrophage activators LPS and phorbol ester (PMA), and the glutathione depleting agent BSO, is reduced by treatment with didox. Moreover, we demonstrate that nuclear translocation of NF-κβ (p65) in response to LPS is inhibited by didox. These findings were supported by qRT-PCR for oxidative stress genes SOD1 and catalase. Overall, this study supports the conclusion that didox may have a future role in managing acute and chronic inflammatory diseases and oxidative stress due to high production of ROS.