Persistently active microbial molecules prolong innate immune tolerance in vivo

Measures that bolster the resolution phase of infectious diseases may offer new opportunities for improving outcome. Here we show that inactivation of microbial lipopolysaccharides (LPS) can be required for animals to recover from the innate immune tolerance that follows exposure to Gram-negative bacteria. When wildtype mice are exposed to small parenteral doses of LPS or Gram-negative bacteria, their macrophages become reprogrammed (tolerant) for a few days before they resume normal function. Mice that are unable to inactivate LPS, in contrast, remain tolerant for several months; during this time they respond sluggishly to Gram-negative bacterial challenge, with high mortality. We show here that prolonged macrophage reprogramming is maintained in vivo by the persistence of stimulatory LPS molecules within the cells' in vivo environment, where naïve cells can acquire LPS via cell-cell contact or from the extracellular fluid. The findings provide strong evidence that inactivation of a stimulatory microbial molecule can be required for animals to regain immune homeostasis following parenteral exposure to bacteria. Measures that disable microbial molecules might enhance resolution of tissue inflammation and help restore innate defenses in individuals recovering from many different infectious diseases.

We showed previously that mice lacking acyloxyacyl hydrolase (AOAH), the host enzyme that inactivates Gram-negative bacterial lipopolysaccharides (LPS), are unable to regain normal immune responsiveness for many weeks/months after they are exposed in vivo to a small amount of LPS or Gram-negative bacteria. The many possible explanations for slow recovery included long-lasting epigenetic changes in macrophages or other host cells, chronically stimulated cells that produce certain mediators, and persistent signaling by internalized LPS within macrophages. Using several in vivo techniques to study peritoneal macrophages, we found that none of these mechanisms was correct. Rather, prolonged recovery is caused by intact LPS that remains in the environment where macrophages live and can pass from one cell to another in vivo. This is the first evidence that the persistence of a bioactive microbial agonist, per se, can prevent resolution of inflammation in vivo. It also identifies the stimulatory microbial molecule as a realistic target for intervention – in further support, we found that providing recombinant AOAH can be partially preventive. In a larger sense, showing that chemical inactivation of one important microbial signaling molecule is required for full recovery should encourage efforts to find out whether disabling other microbial agonists (chitin, lipopeptides, flagella, others) also benefits infected animals.

Macrophage activation by heparanase is mediated by TLR-2 and TLR-4 and associates with plaque progression

OBJECTIVE

Factors and mechanisms that activate macrophages in atherosclerotic plaques are incompletely understood. We examined the capacity of heparanase to activate macrophages.

METHODS AND RESULTS

Highly purified heparanase was added to mouse peritoneal macrophages and macrophage-like J774 cells, and the levels of tumor necrosis factor-α, matrix metalloproteinase-9, interlukin-1, and monocyte chemotactic protein-1 were evaluated by ELISA. Gene expression was determined by RT-PCR. Cells collected from Toll-like receptor-2 and Toll-like receptor-4 knockout mice were evaluated similarly. Heparanase levels in the plasma of patients with acute myocardial infarction, stable angina, and healthy subjects were determined by ELISA. Immunohistochemistry was applied to detect the expression of heparanase in control specimens and specimens of patients with stable angina or acute myocardial infarction. Addition or overexpression of heparanase variants resulted in marked increase in tumor necrosis factor-α, matrix metalloproteinase-9, interlukin-1, and monocyte chemotactic protein-1 levels. Mouse peritoneal macrophages harvested from Toll-like receptor-2 or Toll-like receptor-4 knockout mice were not activated by heparanase. Plasma heparanase level was higher in patients with acute myocardial infarction, compared with patients with stable angina and healthy subjects. Pathologic coronary specimens obtained from vulnerable plaques showed increased heparanase staining compared with specimens of stable plaque and controls.

CONCLUSIONS

Heparanase activates macrophages, resulting in marked induction of cytokine expression associated with plaque progression toward vulnerability.

[Comparative analysis of morphofunctional indicators of peritoneal macrophages in mice of the cancer line A/SN and white outbred mice]

A study of the functional state of peritoneal macrophages was conducted of white outbred mice (W/o) which were resistant to cancer pathology as well as the mice of the A/sn line prone to development of cancer diseases. It was reveald that due to induction of aseptic inflammation ( induced by starch administration), chemotaxis of macrophages of the oncological line was 2.5-3 times reduced and capacity to adhesion was 1.5-2 times lower than capacity of macrophages of the control group (W/o). The paint on F-actin of cytoskeleton in cells showed that cells of the control group form filopodia as a result of adhesion to the substrate, during intercellular contacts as well as during macrophage incubation with retinoic acid. Macrophages A/sn can form pseudopodia when exposed to retinoic acid. Macrophages of both groups of mice were shown to be producer of endonucleases. The same activity of these enzymes was provided by the number of cells which was 1.5-2 times fewer in mice of the A/sn line.

Intracellular chloride channel protein CLIC1 regulates macrophage function through modulation of phagosomal acidification

Intracellular chloride channel protein 1 (CLIC1) is a 241 amino acid protein of the glutathione S transferase fold family with redox- and pH-dependent membrane association and chloride ion channel activity. Whilst CLIC proteins are evolutionarily conserved in Metazoa, indicating an important role, little is known about their biology. CLIC1 was first cloned on the basis of increased expression in activated macrophages. We therefore examined its subcellular localisation in murine peritoneal macrophages by immunofluorescence confocal microscopy. In resting cells, CLIC1 is observed in punctate cytoplasmic structures that do not colocalise with markers for endosomes or secretory vesicles. However, when these macrophages phagocytose serum-opsonised zymosan, CLIC1 translocates onto the phagosomal membrane. Macrophages from CLIC1(-/-) mice display a defect in phagosome acidification as determined by imaging live cells phagocytosing zymosan tagged with the pH-sensitive fluorophore Oregon Green. This altered phagosomal acidification was not accompanied by a detectable impairment in phagosomal-lysosomal fusion. However, consistent with a defect in acidification, CLIC1(-/-) macrophages also displayed impaired phagosomal proteolytic capacity and reduced reactive oxygen species production. Further, CLIC1(-/-) mice were protected from development of serum transfer induced K/BxN arthritis. These data all point to an important role for CLIC1 in regulating macrophage function through its ion channel activity and suggest it is a suitable target for the development of anti-inflammatory drugs.

Antisense to protein kinase C-alpha and p47phox attenuates the pro-inflammatory effects of human C-reactive protein in macrophages of biobreeding diabetic rats

OBJECTIVE

Type 1 diabetes mellitus (T1DM) is a pro-inflammatory state characterized by high C-reactive protein (CRP) levels. Previously, we showed that CRP accentuated a macrophage (MO) activity in spontaneously diabetic biobreeding (BB) rats and increased the MO activity of protein kinase C-alpha (PKC-α) and p47phox. In this report, we tested the effects of molecular inhibition of CRP effects on MO activity using antisense oligonucleotide (ASO) to both PKC-α and p47phox.

METHODS

Prior to administration of human C-reactive protein (hCRP) daily for 3 days, ASO or scrambled ASO to either PKC-α or p47phox was also delivered for 3 days and after killing on day 4, peritoneal MOs were isolated.

RESULTS

The increase in the levels of superoxide anion, interleukin (IL)-1, monocyte chemoattractant protein-1 (MCP-1), tumour necrosis factor-alpha (TNF-α) and IL-6 release in MOs with hCRP compared to human albumin was significantly attenuated by antisense to either PKC-α and p47phox (p < 0.01 vs. scrambled ASO; n = 5 per group).

CONCLUSION

Our novel data suggest that antisense to either PKC-α or p47phox attenuates the pro-inflammatory effects of human CRP on MOs in diabetic rats.

Akt3 deficiency in macrophages promotes foam cell formation and atherosclerosis in mice

Akt, a serine-threonine protein kinase, exists as three isoforms. The Akt signaling pathway controls multiple cellular functions in the cardiovascular system, and the atheroprotective endothelial cell-dependent role of Akt1 has been recently demonstrated. The role of Akt3 isoform in cardiovascular pathophysiology is not known. We explored the role of Akt3 in atherosclerosis using mice with a genetic ablation of the Akt3 gene. Using hyperlipidemic ApoE(-/-) mice, we demonstrated a macrophage-dependent, atheroprotective role for Akt3. In vitro experiments demonstrated differential subcellular localization of Akt1 and Akt3 in macrophages and showed that Akt3 specifically inhibits macrophage cholesteryl ester accumulation and foam cell formation, a critical early event in atherogenesis. Mechanistically, Akt3 suppresses foam cell formation by reducing lipoprotein uptake and promoting ACAT-1 degradation via the ubiquitin-proteasome pathway. These studies demonstrate the nonredundant atheroprotective role for Akt3 exerted via the previously unknown link between the Akt signaling pathway and cholesterol metabolism.

Effect of Nigella sativa seeds extracts on iNOS through antioxidant potential only: crude/total extract as molecular therapy drug

There is general belief that only pure phytomolecules may be used as molecular therapeutic agent through one to one action. However, the traditional systems of medicine e.g. Ayurveda, uses the crude extracts, mostly water decoctions and oils, as drug. A comparative study of hexane, ethyl acetate and methanol fractions of N. Sativa seeds has been carried out on fresh rat-peritoneal-macrophage culture with reference to their role on various targets of lipopolysaccharide induced release of nitric oxide (NO) and inducible nitric oxide synthase (iNOS) expression. The results indicated significant antioxidant potential with methanolic extract as most effective. Its mechanism of action was proposed primarily through its antioxidant potential and not through direct inhibition of other kinases, involved in its signaling cascade.

Rotenone activates phagocyte NADPH oxidase by binding to its membrane subunit gp91phox

Rotenone, a widely used pesticide, reproduces parkinsonism in rodents and associates with increased risk for Parkinson disease. We previously reported that rotenone increased superoxide production by stimulating the microglial phagocyte NADPH oxidase (PHOX). This study identified a novel mechanism by which rotenone activates PHOX. Ligand-binding assay revealed that rotenone directly bound to membrane gp91(phox), the catalytic subunit of PHOX; such binding was inhibited by diphenyleneiodonium, a PHOX inhibitor with a binding site on gp91(phox). Functional studies showed that both membrane and cytosolic subunits were required for rotenone-induced superoxide production in cell-free systems, intact phagocytes, and COS7 cells transfected with membrane subunits (gp91(phox)/p22(phox)) and cytosolic subunits (p67(phox) and p47(phox)). Rotenone-elicited extracellular superoxide release in p47(phox)-deficient macrophages suggested that rotenone enabled activation of PHOX through a p47(phox)-independent mechanism. Increased membrane translocation of p67(phox), elevated binding of p67(phox) to rotenone-treated membrane fractions, and coimmunoprecipitation of p67(phox) and gp91(phox) in rotenone-treated wild-type and p47(phox)-deficient macrophages indicated that p67(phox) played a critical role in rotenone-induced PHOX activation via its direct interaction with gp91(phox). Rac1, a Rho-like small GTPase, enhanced p67(phox)-gp91(phox) interaction; Rac1 inhibition decreased rotenone-elicited superoxide release. In conclusion, rotenone directly interacted with gp91(phox); such an interaction triggered membrane translocation of p67(phox), leading to PHOX activation and superoxide production.

Injection of paraoxonase 1 (PON1) to mice stimulates their HDL and macrophage antiatherogenicity

We analyzed, for the first time, the effects of recombinant PON1 (rePON1) intraperitoneal injection to C₅₇BL/6 mice on their HDL and macrophage antiatherogenic properties. Thioglycolate-treated mice were injected with either saline (Control), or rePON1 (50 μg/mouse), and 20 H post injection, their blood samples and peritoneal macrophages (MPM) were collected. A significant increase in serum and HDL-PON1 arylesterase and lactonase activities was noted. Similarly, a significant increment, by 3.8 and 2.8 fold, in MPM-PON1 arylesterase and lactonase activities, respectively, as compared to the activities in control MPM was observed. The HDL from rePON1-injected mice was resistant to oxidation by copper ions as compared to control HDL. Furthermore, enrichment of the mouse HDL with rePON1 increased its ability to induce cholesterol efflux from J774A.1 macrophage cell line, and to inhibit macrophage-mediated LDL oxidation. In MPM from rePON1-injected mice vs. control MPM, there was a significant reduction in cholesterol mass, by 42%, in association with inhibition in cellular cholesterol biosynthesis rate, by 33%, and with significant stimulation, by 65%, of human HDL-mediated cholesterol efflux from the cells. We conclude that rePON1 injection to mice improved the mice HDL and MPM antiatherogenic properties, and these effects could probably lead to attenuation of atherosclerosis development.

Identification of Soat1 as a quantitative trait locus gene on mouse chromosome 1 contributing to hyperlipidemia

We previously identified two closely linked quantitative trait loci (QTL) on distal chromosome 1 contributing to major variations in plasma cholesterol and triglyceride levels in an intercross derived from C57BL/6 (B6) and C3H/HeJ (C3H) apolipoprotein E-deficient (apoE^−/−) mice. Soat1, encoding sterol o-acyltransferase 1, is a functional candidate gene located underneath the proximal linkage peak. We sequenced the coding region of Soat1 and identified four single nucleotide polymorphisms (SNPs) between B6 and C3H mice. Two of the SNPs resulted in amino-acid substitutions (Ile147Val and His205Tyr). Functional assay revealed an increased enzyme activity of Soat1 in peritoneal macrophages of C3H mice relative to those of B6 mice despite comparable protein expression levels. Allelic variants of Soat1 were associated with variations in plasma cholesterol and triglyceride levels in an intercross between B6.apoE^−/− and C3H.apoE^−/− mice. Inheritance of the C3H allele resulted in significantly higher plasma lipid levels than inheritance of the B6 allele. Soat1 variants were also significantly linked to major variations in plasma esterified cholesterol levels but not with free cholesterol levels. Trangenic expression of C3H Soat1 in B6.apoE^−/− mice resulted in elevations of plasma cholesterol and triglyceride levels. These results indicate that Soat1 is a QTL gene contributing to hyperlipidemia.

A novel compound C12 inhibits inflammatory cytokine production and protects from inflammatory injury in vivo

Inflammation is a hallmark of many diseases. Although steroids and cyclooxygenase inhibitors are main anti-inflammatory therapeutical agents, they may cause serious side effects. Therefore, developing non-steroid anti-inflammatory agents is urgently needed. A novel hydrosoluble compound, C12 (2,6-bis(4-(3-(dimethylamino)-propoxy)benzylidene)cyclohexanone), has been designed and synthesized as an anti-inflammatory agent in our previous study. In the present study, we investigated whether C12 can affect inflammatory processes in vitro and in vivo. In mouse primary peritoneal macrophages, C12 potently inhibited the production of the proinflammatory gene expression including TNF-α, IL-1β, IL-6, iNOS, COX-2 and PGE synthase. The activity of C12 was partly dependent on inhibition of ERK/JNK (but p38) phosphorylation and NF-κB activation. In vivo, C12 suppressed proinflammatory cytokine production in plasma and liver, attenuated lung histopathology, and significantly reduced mortality in endotoxemic mice. In addition, the pre-treatment with C12 reduced the inflammatory pain in the acetic acid and formalin models and reduced the carrageenan-induced paw oedema and acetic acid-increased vascular permeability. Taken together, C12 has multiple anti-inflammatory effects. These findings, coupled with the low toxicity and hydrosolubility of C12, suggests that this agent may be useful in the treatment of inflammatory diseases.

The inhibitory activities of the components of Huang-Lian-Jie-Du-Tang (HLJDT) on eicosanoid generation via lipoxygenase pathway

AIM OF THE STUDY

Huang-Lian-Jie-Du-Tang (HLJDT) is a traditional Chinese medicine with anti-inflammatory use. In the present study, the effects of its component herbs and pure components were observed on eicosanoid generation to find out the contributory components and their precise targets on arachidonic acid (AA) cascade.

MATERIALS AND METHODS

By monitoring leukotriene B(4) (LTB(4)), 5-hydroxyeicosatetraenoic acid (5-HETE), and 12-hydroxy-5,8,10-heptadecatrienoic acid (12-HHT), we compared the effects of HLJDT, HLJDT free of one or two component herbs, and water extract of four single component herbs of HLJDT (Rhizoma coptidis, Radix scutellariae, Cortex phellodendri and Fructus gardeniae) on eicosanoid generation in rat elicited peritoneal macrophages. In addition, thirteen pure compounds from HLJDT (baicalin, baicalein, wogonoside, wogonin, berberine, magnoflorine, phellodendrine, coptisine, palmatine, jateorrhizine, crocin, chlorogenic acid, and geniposide) were tested in the macrophages. Furthermore, the efficacies of these thirteen compounds were evaluated on cell-free purified enzymes: leukotriene A(4) hydrolase (LTA(4)H), 5-, 15-lipoxygenase (5-, 15-LO), and cyclo-oxygenase-1/2 (COX-1/2). Moreover, the possible synergetic effect on LO pathway derived LTB(4) generation between the active components was also tested in rat peritoneal macrophages.

RESULTS

Our experiments showed that Rhizoma coptidis and Radix scutellariae were responsible for the suppressive effect of HLJDT on eicosanoid generation. Some of the pure components including baicalein, baicalin, wogonoside, wogonin, coptisine, and magnoflorine inhibited eicosanoid generation in rat macrophages via LO pathway of AA cascade. Further experiments on cell-free purified enzymes confirmed that Radix scutellariae derived baicalein and baicalin showed significant inhibition on 5-LO and 15-LO, while Rhizoma coptidis derived coptisine showed medium inhibition on LTA(4)H. On the other hand, no significant inhibition of thirteen components on COX-1/2 was observed. Moreover, the slight synergetic inhibition on LTB(4) between baicalein and coptisine was proved in the rat peritoneal macrophages.

CONCLUSIONS

Baicalein and coptisine, the active components of HLJDT, for the first time are found to interfere with arachidonic acid cascade via inhibition on different points of LO pathway. This finding makes the mechanism of HLJDT clearer and achieves its safer therapeutic application.

Effects of andrographolide on the activation of mitogen activated protein kinases and nuclear factor-κB in mouse peritoneal macrophage-derived foam cells

OBJECTIVE

To observe the effect of andrographolide on the activation of mitogen-activated protein kinases (MAPKs) and expression of nuclear factor-κB (NF-κB) in macrophage foam cells.

METHODS

The mouse peritoneal macrophages were cultured in the media in the presence of oxidized low-density lipoprotein (ox-LDL), ox-LDL+andrographolide, or neither (control). The phosphorylation of MAPK molecules (p38MAPK, JNK, ERK1/2) and the expressions of NK-κB p65 were examined by Western blot.

RESULTS

As compared with cells in the control group, the expressions of phospho-p38 and NF-κB p65 were increased in the cells cultured with either ox-LDL or ox-LDL+andrographolide (P<0.01), but attenuated significantly in the presence of ox-LDL+ andrographolide when compared with ox-LDL (P<0.05). The phospho-JNK increased in the presence of either ox-LDL or ox-LDL+andrographolide when compared with control cells (P<0.01), but no significant difference existed between ox-LDL and ox-LDL+andrographolide (P>0.05). The expression of phospho-ERK1/2 was increased in the presence of ox-LDL compared with the control cells (P<0.01), but no significant differences existed between the cells cultured in the presence of ox-LDL+andrographolide and the control medium (P>0.05).

CONCLUSIONS

Andrographolide could inhibit the activation of ERK1/2, p38MAPK and NK-κB induced by ox-LDL in macrophage foam cells, which might be one of its mechanisms in preventing atherosclerosis.

Immunostimulating activity by polysaccharides isolated from fruiting body of Inonotus obliquus

In this study, we investigated the immunostimulating activity of polysaccharides isolated from fruiting body of Inonotus obliquus (PFIO). Additionally, the signaling pathway of PFIO-mediated macrophage activation was investigated in RAW264.7 macrophage cells. We found that PFIO was capable of promoting NO/ROS production, TNF-α secretion and phagocytic uptake in macrophages, as well as cell proliferation, comitogenic effect and IFN-γ/IL-4 secretion in mouse splenocytes. PFIO was able to induce the phosphorylation of three MAPKs as well as the nuclear translocation of NF-κB, resulting in activation of RAW264.7 macrophages. PFIO also induced the inhibition of TNF-α secretion by anti-TLR2 mAb, consequently, PFIO might be involved in TNF-α secretion via the TLR2 receptor. In addition, our results showed that oral administration of PFIO suppressed in vivo growth of melanoma tumor in tumorbearing mice. In conclusion, our experiments presented that PFIO effectively promotes macrophage activation through the MAPK and NF-κB signaling pathways, suggesting that PFIO may potentially regulate the immune response.

Pathways regulating cytosolic phospholipase A2 activation and eicosanoid production in macrophages by Candida albicans

Resident tissue macrophages are activated by the fungal pathogen Candida albicans to release eicosanoids, which are important modulators of inflammation and immune responses. Our objective was to identify the macrophage receptors engaged by C. albicans that mediate activation of group IVA cytosolic phospholipase A(2) (cPLA(2)α), a regulatory enzyme that releases arachidonic acid (AA) for production of prostaglandins and leukotrienes. A comparison of peritoneal macrophages from wild type and knock-out mice demonstrates that the β-glucan receptor Dectin-1 and MyD88 regulate early release of AA and eicosanoids in response to C. albicans. However, cyclooxygenase 2 (COX2) expression and later phase eicosanoid production are defective in MyD88(-/-) but not Dectin-1(-/-) macrophages. Furthermore, C. albicans-stimulated activation of MAPK and phosphorylation of cPLA(2)α on Ser-505 are regulated by MyD88 and not Dectin-1. In contrast, Dectin-1 mediates MAPK activation, cPLA(2)α phosphorylation, and COX2 expression in response to particulate β-glucan suggesting that other receptors engaged by C. albicans preferentially mediate these responses. Results also implicate the mannan-binding receptor Dectin-2 in regulating cPLA(2)α. C. albicans-stimulated MAPK activation and AA release are blocked by d-mannose and Dectin-2-specific antibody, and overexpression of Dectin-2 in RAW264.7 macrophages enhances C. albicans-stimulated MAPK activation, AA release, and COX2 expression. In addition, calcium mobilization is enhanced in RAW264.7 macrophages overexpressing Dectin-1 or -2. The results demonstrate that C. albicans engages both β-glucan and mannan-binding receptors on macrophages that act with MyD88 to regulate the activation of cPLA(2)α and eicosanoid production.

In vitro and in vivo immunostimulatory activity of Woodfordia fruticosa flowers on non-specific immunity

CONTEXT

Woodfordia fruticosa Kurz. (Lythraceae), a non-rasayana immunomodulatory Indian medicinal plant, used traditionally as an anthelmintic, in dysentery, leprosy, blood diseases, leucorrhea, and menorrhagia.

OBJECTIVE

To investigate the effect of ethanol extract of W. fruticosa flowers on non-specific immune responses in mice.

MATERIALS AND METHODS

In vitro immunomodulatory activity of the extract was examined on murine peritoneal macrophage phagocytosis (nitroblue tetrazolium (NBT) dye reduction, lysosomal enzyme activity, nitric oxide and myeloperoxidase) and on proliferation of bone marrow cells by sulforhodamine B (SRB) assay, while the in vivo potential on macrophages and bone marrow cells was evaluated by using carbon clearance test and cyclophosphamide-induced myelosuppression, respectively.

RESULTS

Significant increase in the release of myeloperoxidase, nitric oxide lysosomal enzyme and superoxide from macrophages along with significant increase in phagocytic index in carbon clearance test indicate stimulatory activity of the extract on macrophages. The extract also demonstrated 60% increase in bone marrow cell proliferation and offer protection towards cyclophosphamide-induced myelosuppression which represents the stimulation of bone marrow activity.

DISCUSSION

Significant increase in mediators released from macrophages and phagocytic index in carbon clearance test suggests the release of cytokines from macrophages and stimulation of reticulo-endothelial system. Proliferation of bone marrow cells indicates the plausible release of colony stimulating factors, which further stimulates the immune system through generation of immune cells.

CONCLUSION

The result described here indicates the immunostimulatory activity of ethanol extract of W. fruticosa flowers by stimulating non-specific immune responses, macrophages and bone marrow cells.

[Sphingomyelin synthase 2 deficiency decreases atherosclerosis and inhibits inflammation in mice]

Plasma sphingomyelin (SM) has been shown to be an independent risk factor for coronary heart disease, and sphingomyelin synthase 2 (SMS2) contributes to de novo SM biosynthesis and plasma membrane SM levels. The aim of the present study is to evaluate the in vivo role of SMS2 deficiency in serum SM metabolism and atherosclerosis (AS) development. We used male SMS2 knockout (SMS2(-/-)) and C57BL/6J (wild-type, WT) mice as experimental and control groups, respectively. Each group was fed high-fat diet (1% cholesterol, 20% leaf fat), as well as bile salt for accelerating the atherosclerotic formation. After three months of feeding, the mice were killed to observe aortic arches and oil red-stained longitudinal sections of thoracoabdominal aortae. Fasting blood samples were taken from the tail vein before and after high-fat diet, and the serum lipid and SM levels were measured by using kits and enzymatic method respectively. Western blot was used to analyze the contents of nuclear factor-kappaB (NFkappaB) p65 subunit in peritoneal macrophages stimulated with lipopolysaccharide (LPS) after high-fat diet. The results showed that after high-fat diet, SMS2(-/-) mice presented decreased atherosclerotic lesions in aortic arch and thoracoabdominal aorta compared with WT mice. Regardless of whether high-fat diet were given or not, SMS2(-/-) mice showed a significant decrease in serum SM level (P<0.05), but no significant changes in serum lipid levels, compared with WT mice. The expressions of NFkappaB p65 were attenuated in macrophages from SMS2(-/-) mice in response to LPS stimulation compared with those of the WT mice. These results suggest that SMS2 deficiency decreases AS and inhibits inflammation in mice. Thus, SMS2 deficiency may be a potential therapeutic strategy.

Substrate fate in activated macrophages: a comparison between innate, classic, and alternative activation

Macrophages play a relevant role in innate and adaptive immunity depending on the balance of the stimuli received. From an analytical and functional point of view, macrophage stimulation can be segregated into three main modes, as follows: innate, classic, and alternative pathways. These differential activations result in the expression of specific sets of genes involved in the release of pro- or anti-inflammatory stimuli. In the present work, we have analyzed whether specific metabolic patterns depend on the signaling pathway activated. A [1,2-(13)C(2)]glucose tracer-based metabolomics approach has been used to characterize the metabolic flux distributions in macrophages stimulated through the classic, innate, and alternative pathways. Using this methodology combined with mass isotopomer distribution analysis of the new formed metabolites, the data show that activated macrophages are essentially glycolytic cells, and a clear cutoff between the classic/innate activation and the alternative pathway exists. Interestingly, macrophage activation through LPS/IFN-gamma or TLR-2, -3, -4, and -9 results in similar flux distribution patterns regardless of the pathway activated. However, stimulation through the alternative pathway has minor metabolic effects. The molecular basis of the differences between these two types of behavior involves a switch in the expression of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK2) from the liver type-PFK2 to the more active ubiquitous PFK2 isoenzyme, which responds to Hif-1alpha activation and increases fructose-2,6-bisphosphate concentration and the glycolytic flux. However, using macrophages targeted for Hif-1alpha, the switch of PFK2 isoenzymes still occurs in LPS/IFN-gamma-activated macrophages, suggesting that this pathway regulates ubiquitous PFK2 expression through Hif-1alpha-independent mechanisms.

[Effect of plant polysaccharides on TH1-dependent immune response: screening investigation]

We have studied the influence of water-soluble polysaccharides isolated from Tussilago farfara L. leaves, Betula verrucosa Ehrh. leaves, Calendula officinalis L. flowers, Acorus calamus rhizomes, Inula helenium L. rhizomes, overground part of Trifolium pretense L., and overground part ofArtemisia absinthium L., on Thl immune response induced by sheep red blood cells and on NO production by murine peritoneal macrophages in vitro. All the investigated polysaccharides have stimulated a Th1 response. Polysaccharides isolated from Betula verrucosa leaves did not influence NO synthesis, while polysaccharides of Tussilago farfara leaves and Acorus calamus rhizomes stimulated NO synthase of murine macrophages on a level comparable with that of lipopolysaccharides (LPS). Polysaccharides from Inula helenium rhizomes, Calendula officinalis flowers, and overground parts of Trifolium pretense and Artemisia absinthium also stimulated NO production, but to a lower extent in comparison to LPS.

[Comparative characteristics of oxygen-dependent and nitroxide-forming enzymatic systems of macrophages in Staphylococcus aureus and Listeria monocytogenes infections]

The reactivity of oxide-dependent and nitroxide-forming enzymatic systems of macrophages infected by bacteria, characterized by intraphagosomal (Staphylococcus aureus) and intracytoplasmatic (Listeria monocytogenes) localization in the phagocyte has been investigated. The correlation analysis revealed links between indices of the activity of oxide-dependent and nitroxide-forming enzymatic systems of infected macrophages.

Cerebral and peripheral changes occurring in nitric oxide (NO) synthesis in a rat model of sleeping sickness: identification of brain iNOS expressing cells

BACKGROUND

The implication of nitric oxide (NO) in the development of human African trypanosomiasis (HAT) using an animal model, was examined. The manner by which the trypanocidal activity of NO is impaired in the periphery and in the brain of rats infected with Trypanosoma brucei brucei (T. b. brucei) was analyzed through: (i) the changes occurring in NO concentration in both peripheral (blood) and cerebral compartments; (ii) the activity of nNOS and iNOS enzymes; (iii) identification of the brain cell types in which the NO-pathways are particularly active during the time-course of the infection.

METHODOLOGY/PRINCIPAL FINDINGS

NO concentration (direct measures by voltammetry) was determined in central (brain) and peripheral (blood) compartments in healthy and infected animals at various days post-infection: D5, D10, D16 and D22. Opposite changes were observed in the two compartments. NO production increased in the brain (hypothalamus) from D10 (+32%) to D16 (+71%), but decreased in the blood from D10 (-22%) to D16 (-46%) and D22 (-60%). In parallel with NO measures, cerebral iNOS activity increased and peaked significantly at D16 (up to +700%). However, nNOS activity did not vary. Immunohistochemical staining confirmed iNOS activation in several brain regions, particularly in the hypothalamus. In peritoneal macrophages, iNOS activity decreased from D10 (-83%) to D16 (-65%) and D22 (-74%) similarly to circulating NO.

CONCLUSION/SIGNIFICANCE

The NO changes observed in our rat model were dependent on iNOS activity in both peripheral and central compartments. In the periphery, the NO production decrease may reflect an arginase-mediated synthesis of polyamines necessary to trypanosome growth. In the brain, the increased NO concentration may result from an enhanced activity of iNOS present in neurons and glial cells. It may be regarded as a marker of deleterious inflammatory reactions.

Endomorphin-suppressed nitric oxide release from mice peritoneal macrophages

Endomorphins are newly discovered mu-opioid receptor selective immunocompetent opioid peptides. Endomorphin 1 is predominantly distributed in brain, while endomorphin 2 is widely allocated in the spinal cord. Lately, endomorphins have been investigated as modulators of reactive oxygen and nitrogen species. Nitric oxide is short lived radical involved in various biological processes such as regulation of blood vessel contraction, inflammation, neurotransmission and apoptosis. The aim of this work was to investigate the in vivo effects of endomorphins on nitric oxide release and NOS 2 isoenzyme upregulation in mice peritoneal macrophages additionally challenged ex vivo with lipopolysaccharide. The results showed that endomorphin 1 or endomorphin 2 in vitro did not change NO release from peritoneal mouse macrophages during a 48 h incubation period. On the other hand in vivo endomorphins had suppressive effect on NO release as well as on NOS 2 and IL-1 protein concentration. The most of suppressive effect in vivo of both endomorphins was blocked with 30 min pretreatment with mu-receptor selective antagonist beta-FNA, which proved involvement of opioid receptor pathway in suppressive effects of endomorphins.

IL-2 regulates SEB induced toxic shock syndrome in BALB/c mice

BACKGROUND

Toxic Shock Syndrome (TSS) is characterized by fever, rash, hypotension, constitutional symptoms, and multi-organ involvement and is caused by Staphylococcus aureus enterotoxins such as Staphylococcal Enterotoxin B (SEB). SEB binds to the MHC-IIalpha chain and is recognized by the TCRbeta chain of the Vbeta8 TCR(+) T cells. The binding of SEB to Vbeta chain results in rapid activation of T cells and production of inflammatory cytokines, such as Interleukin-2 (IL-2), Interferon-gamma and Tumor Necrosis Factor-alpha which mediate TSS. Although IL2 was originally identified as the T cell growth factor and was proposed to contribute to T cell differentiation, its role in TSS remains unexplored.

METHODOLOGY/PRINCIPAL FINDINGS

Mice were injected with D-Gal (25 mg/mouse). One hour after D-Galactosamine (D-Gal) injection each mouse was injected with SEB (20 microg/mouse. Mice were then observed for 72 hrs and death was recorded at different times. We tested Interleukin-12, IFNgamma, and IL-2 deficient mice (IL-2(-/-)), but only the IL-2 deficient mice were resistant to SEB induced toxic shock syndrome. More importantly reconstitution of IL-2 in IL-2 deficient mice restored the shock. Interestingly, SEB induced IL-2 production from T cells was dependent on p38MAPK activation in macrophages as inhibition of it in macrophages significantly inhibited IL-2 production from T cells.

CONCLUSION

This study shows the importance of IL -2 in TSS which has not been previously explored and it also shows that regulating macrophages function can regulate T cells and TSS.

Antibody complementarity-determining regions (CDRs): a bridge between adaptive and innate immunity

BACKGROUND

It has been documented that, independently from the specificity of the native antibody (Ab) for a given antigen (Ag), complementarity determining regions (CDR)-related peptides may display differential antimicrobial, antiviral and antitumor activities.

METHODOLOGY/PRINCIPAL FINDINGS

In this study we demonstrate that a synthetic peptide with sequence identical to V(H)CDR3 of a mouse monoclonal Ab (mAb) specific for difucosyl human blood group A is easily taken up by macrophages with subsequent stimulation of: i) proinflammatory cytokine production; ii) PI3K-Akt pathway and iii) TLR-4 expression. Significantly, V(H)CDR3 exerts therapeutic effect against systemic candidiasis without possessing direct candidacidal properties.

CONCLUSIONS/SIGNIFICANCE

These results open a new scenario about the possibility that, beyond the half life of immunoglobulins, Ab fragments may effectively influence the antiinfective cellular immune response in a way reminiscent of regulatory peptides of innate immunity.