Lipopolysaccharide-stimulated nitric oxide production and inhibition of cell proliferation is antagonized by ethanol in a clonal macrophage cell line

Extracellular Proteins Isolated from L. acidophilus as an Osteomicrobiological Therapeutic Agent to Reduce Pathogenic Biofilm Formation, Regulate Chronic Inflammation, and Augment Bone Formation In Vitro

Periprosthetic joint infection (PJI) is a challenging complication that can occur following joint replacement surgery. Efficacious strategies to prevent and treat PJI and its recurrence remain elusive. Commensal bacteria within the gut convey beneficial effects through a defense strategy named "colonization resistance" thereby preventing pathogenic infection along the intestinal surface. This blueprint may be applicable to PJI. The aim is to investigate Lactobacillus acidophilus spp. and their isolated extracellular-derived proteins (LaEPs) on PJI-relevant Staphylococcus aureus, methicillin-resistant S. aureus, and Escherichia coli planktonic growth and biofilm formation in vitro. The effect of LaEPs on cultured macrophages and osteogenic, and adipogenic human bone marrow-derived mesenchymal stem cell differentiation is analyzed. Data show electrostatically-induced probiotic-pathogen species co-aggregation and pathogenic growth inhibition together with LaEP-induced biofilm prevention. LaEPs prime macrophages for enhanced microbial phagocytosis via cathepsin K, reduce lipopolysaccharide-induced DNA damage and receptor activator nuclear factor-kappa B ligand expression, and promote a reparative M2 macrophage morphology under chronic inflammatory conditions. LaEPs also significantly augment bone deposition while abating adipogenesis thus holding promise as a potential multimodal therapeutic strategy. Proteomic analyses highlight high abundance of lysyl endopeptidase, and urocanate reductase. Further, in vivo analyses are warranted to elucidate their role in the prevention and treatment of PJIs.

Lipopolysaccharide affects energy metabolism and elevates nicotinamide N-methyltransferase level in human aortic endothelial cells (HAEC)

This study aimed to investigate the putative role of nicotinamide N-methyltransferase in the metabolic response of human aortic endothelial cells. This enzyme catalyses S-adenosylmethionine-mediated methylation of nicotinamide to methylnicotinamide. This reaction is accompanied by the reduction of the intracellular nicotinamide and S-adenosylmethionine content. This may affect NAD⁺ synthesis and various processes of methylation, including epigenetic modifications of chromatin. Particularly high activity of nicotinamide N-methyltransferase is detected in liver, many neoplasms as well as in various cells in stressful conditions. The elevated nicotinamide N-methyltransferase content was also found in endothelial cells treated with statins. Although the exogenous methylnicotinamide has been postulated to induce a vasodilatory response, the specific metabolic role of nicotinamide N-methyltransferase in vascular endothelium is still unclear. Treatment of endothelial cells with bacterial lipopolysaccharide evokes several metabolic and functional consequences which built a multifaceted physiological response of endothelium to bacterial infection. Among the spectrum of biochemical changes substantially elevated protein level of nicotinamide N-methyltransferase was particularly intriguing. Here it has been shown that silencing of the nicotinamide N-methyltransferase gene influences several changes which are observed in cells treated with lipopolysaccharide. They include altered energy metabolism and rearrangement of the mitochondrial network. A complete explanation of the mechanisms behind the protective consequences of the nicotinamide N-methyltransferase deficiency in cells treated with lipopolysaccharide needs further investigation.

Anti-Inflammatory Comparison of Melatonin and Its Bromobenzoylamide Derivatives in Lipopolysaccharide (LPS)-Induced RAW 264.7 Cells and Croton Oil-Induced Mice Ear Edema

The pineal gland is a neuroendocrine organ that plays an important role in anti-inflammation through the hormone melatonin. The anti-inflammatory effects of melatonin and its derivatives have been reported in both in vitro and in vivo models. Our previous study reported the potent antioxidant and neuroprotective activities of bromobenzoylamide substituted melatonin. In silico analysis successfully predicted that melatonin bromobenzoylamid derivatives were protected from metabolism by CYP2A1, which is a key enzyme of the melatonin metabolism process. Therefore, the anti-inflammatory activities of melatonin and its bromobenzoylamide derivatives BBM and EBM were investigated in LPS-induced RAW 264.7 macrophages and croton oil-induced ear edema in mice. The experiments showed that BBM and EBM significantly reduced production of the inflammatory mediators interleukin-6 (IL-6), prostaglandin E2 (PGE₂), and nitric oxide (NO) in a dose-dependent manner, but only slightly affected TNF-α in LPS-induced RAW 264.7 macrophages. This suggests that modifying melatonin at either the N1-position or the N-acetyl side chain affected production of NO, PGE₂ and IL-6 in in vitro model. In the croton oil-induced mouse ear edema model, BBM, significantly decreased ear edema thickness at 2-4 h. It leads to conclude that bromobenzoylamide derivatives of melatonin may be one of the potential candidates for a new type of anti-inflammatory agent.

Hetero-Polysaccharides Secreted from Dunaliella salina Exhibit Immunomodulatory Activity Against Peripheral Blood Mononuclear Cells and RAW 264.7 Macrophages

Several species of microalgae have been known to produce exopolysaccharides (EPS) with potential immune activity. In the present investigation, ethyl acetate fraction of crude EPS secreted by Dunaliella salina was explored for immunomodulatory activity against peripheral blood mononuclear cells (PBMC) and RAW 264.7 macrophages. Effect of EPS on cell growth and cytokines production were measured using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and ELISA respectively. Griess reagent was used for measuring the nitric oxide production in RAW 264.7 macrophages. FTIR analysis and mass spectroscopy were carried out for the characterization. Ethyl acetate fraction exhibited dose dependent increase in proliferative index and cytokines production (IFN-γ, TNF-α, TGF-β). At low concentration (250 and 500 µg/mL), it showed growth inhibition and at higher concentration (1000 and 1500 µg/mL), it enhanced the cell growth. Interestingly, the pronounced increased TNF-α production was observed in ethyl acetate fraction treated PBMC cells at higher concentration (750 and 1000 µg/mL) indicating the immunostimulatory effect. In RAW cells, concentration dependent diminished cell growth (IC₅₀ = 691 µg/mL) and nitric oxide production (IC₅₀ = 630 µg/mL) was observed. FTIR analysis showed the presence of polysaccharides due to the detection of hydroxyl (-OH), Carbonyl (C-O) and alkyl (C-H) groups. Mass spectroscopy results revealed ethyl acetate fraction as penta-saccharide (m/z = 887.56 and 886.54) which are confirmed to be hetero-polysaccharides consisting of hexoses and pentoses along with association of ions. These results suggest that penta-saccharide (ethyl acetate fraction) isolated from D. salina may have the potential to be used for therapeutic purpose as immunomodulatory agent.

Supplementation of Plants with Immunomodulatory Properties during Pregnancy and Lactation-Maternal and Offspring Health Effects

A pregnant woman’s diet consists of many products, such as fruits, vegetables, cocoa, tea, chocolate, coffee, herbal and fruit teas, and various commercially available dietary supplements, which contain a high number of biological active plant-derived compounds. Generally, these compounds play beneficial roles in women’s health and the development of fetus health. There are, however, some authors who report that consuming excessive amounts of plants that contain high concentrations of polyphenols may negatively affect the development of the fetus and the offspring’s health. Important and problematic issues during pregnancy and lactation are bacterial infections treatment. In the treatment are proposals to use plant immunomodulators, which are generally considered safe for women and their offspring. Additional consumption of biologically active compounds from plants, however, may increase the risk of occurrences to irreversible changes in the offspring’s health. Therefore, it is necessary to carry out safety tests for immunomodulators before introducing them into a maternal diet. Here, we present data from animal experiments for the four most-studied plants immunomodulators genus: Rhodiola, Echinacea, Panax, and Camellia, which were used in maternal nutrition.

Rosiglitazone blocks first trimester in-vitro placental injury caused by NF-κB-mediated inflammation

Increased inflammation and abnormal placentation are common features of a wide spectrum of pregnancy-related disorders such as intra uterine growth restriction, preeclampsia and preterm birth. The inflammatory response of the human placenta has been mostly investigated in relation to cytokine release, but the direct molecular consequences on trophoblast differentiation have not been investigated. This study measured the general effects of LPS on both extravillous and villous trophoblast physiology, and the involvement of the transcription factors PPARγ and NF-κB, specifically using 1^st trimester explants and HTR-8/ SVneo cell line models. While both proteins are known for their roles in inflammatory pathways, PPARγ has been identified as an important molecule in trophoblast differentiation, suggesting its potential role in mediating a crosstalk between inflammation and trophoblast differentiation. Here, LPS (1 µg/ml) exposure of first trimester placental villous explants resulted in secretion of inflammatory cytokines, induction of apoptosis and reduction in trophoblast cell proliferation. Additionally, LPS significantly reduced expression of the trophoblast differentiation proteins GCM1 and β-hCG, and increased invasion of the extravillous trophoblast. Activation of PPARγ by Rosiglitazone (10 µM) reversed the LPS-mediated effects on inflammatory cytokine release, trophoblast apoptosis and proliferation compared to controls. Lastly, markers of trophoblast differentiation and invasion reverted to control levels upon activation of PPARγ and concomitant inhibition of NF-κB (either by Rosiglitazone or NF-κB specific inhibitor), revealing a new role for NF-κB in trophoblast invasion. This study reveals a novel PPARγ - NF-κB axis that coordinates inflammatory and differentiation pathways in the human placenta. The ability to reverse trophoblast-associated inflammation with Rosiglitazone offers promise that the PPARγ - NF-κB pathway could one day provide a therapeutic target for placental dysfunction associated with both inflammation and abnormal trophoblast differentiation.

Antigastritis effects of Armillariella tabescens (Scop.) Sing. and the identification of its anti-inflammatory metabolites

Objectives

This study demonstrates the biological and chemical analysis of the mushroom Armillariella tabescens (Scop.) Sing. (Tricholomataceae).

Methods

Chemical structures of the isolates were determined by 1D and 2D NMR, and ESI-MS, as well as comparison with previously reported data. All isolates were tested for anti-inflammatory effects based on their ability to inhibit LPS-stimulated nitric oxide (NO) production in RAW264.7 cells.

Key findings

We found that the MeOH extract of the fruiting bodies of A. tabescens showed antigastritis activity against ethanol-induced gastric damage in rats and notably reduced the gastric damage index compared to control in a concentration-dependent manner. Chemical investigation of the MeOH extract led to the isolation of four steroids (1–4), three alkaloids (5–7), two nucleic acids (8–9) and four fatty acids (10–13). This is the first study to report the identification of all isolates, except for compound 7, from A. tabescens. Compounds 1, 2, 3, 4 and 10 showed inhibition on LPS-stimulated NO production. Treatment with compound 10 inhibited expression of iNOS, COX-2, phospho-IKKα, IKKα, phospho-IκBα, IκBα and NF-kappa B in LPS-stimulated RAW264.7 cells.

Conclusions

Compound 10 likely contributes to the health benefits of A. tabescens as an antigastritis agent through its anti-inflammatory effects.

Endotoxin contamination of apolipoprotein A-I: effect on macrophage proliferation--a cautionary tale

This technical report addresses the problem of endotoxin contamination of apolipoprotein reagents. Using a bromodeoxyuridine incorporation cell proliferation assay, we observed that human plasma ApoA-I as low as 1 μg/ml resulted in a >90% inhibition in macrophage proliferation. However, not all ApoA-I from different sources showed this effect. We considered the possibility that endotoxin contamination of the apolipoproteins contributed to the differential inhibition of macrophage cell proliferation. Endotoxin alone very potently inhibited macrophage proliferation (0.1 ng/ml inhibited macrophage proliferation>90%). Measurement of endotoxin levels in the apolipoprotein products, including an analysis of free versus total endotoxin, the latter which included endotoxin that was masked due to binding to protein, suggested that free endotoxin mediated inhibition of macrophage proliferation. Despite the use of an advanced endotoxin removal procedure and agents commonly used to inhibit endotoxin action, the potency of endotoxin precluded successful elimination of endotoxin effect. Our findings show that endotoxin contamination can significantly influence apparent apolipoprotein-mediated cell effects (or effects of any other biological products), especially when these products are tested on highly endotoxin-sensitive cells, such as macrophages.

Reducing the Foreign Body Reaction by Surface Modification with Collagen/Hyaluronic Acid Multilayered Films

Biological response against foreign implants often leads to encapsulation, possibly resulting in malfunction of implants devices. The aim of this study was to reduce the foreign body reaction by surface modification of biomaterials through layer-by-layer deposition of type I collagen (COL)/hyaluronic acid (HA) multilayer films. Polydimethylsiloxane (PDMS) samples were coated with alternative COL and HA layers with different layers. We found that the in vitro adhesion, proliferation, and activation of macrophage-like cells were greatly decreased by COL/HA multilayered deposition. The PDMS samples modified with 20 bilayers of COL/HA were implanted in rats for 3 weeks, and the thickness of encapsulation surrounding the samples was decreased by 29–57% compared to the control unmodified PDMS. This study demonstrates the potential of COL/HA multilayer films to reduce foreign body reaction.

Rapid temporal dynamics of transcription, protein synthesis, and secretion during macrophage activation

Macrophages provide the first line of host defense with their capacity to react to an array of cytokines and bacterial components requiring tight regulation of protein expression and secretion to invoke a properly tuned innate immune response. To capture the dynamics of this system, we introduce a novel method combining pulsed stable isotope labeling with amino acids in cell culture (SILAC) with pulse labeling using the methionine analog azidohomoalanine that allows the enrichment of newly synthesized proteins via click-chemistry followed by their identification and quantification by mass spectrometry. We show that this permits the analysis of proteome changes on a rapid time scale, as evidenced by the detection of 4852 newly synthesized proteins after only a 20-min SILAC pulse. We have applied this methodology to study proteome response during macrophage activation in a time-course manner. We have combined this with full proteome, transcriptome, and secretome analyses, producing an integrative analysis of the first 3 h of lipopolysaccharide-induced macrophage activation. We observed the rapid induction of multiple processes well known to TLR4 signaling, as well as anti-inflammatory proteins and proteins not previously associated with immune response. By correlating transcriptional, translational, and secretory events, we derived novel mechanistic principles of processes specifically induced by lipopolysaccharides, including ectodomain shedding and proteolytic processing of transmembrane and extracellular proteins and protein secretion independent of transcription. In conclusion, we demonstrate that the combination of pulsed azidohomoalanine and pulsed SILAC permits the detailed characterization of proteomic events on a rapid time scale. We anticipate that this approach will be very useful in probing the immediate effects of cellular stimuli and will provide mechanistic insight into cellular perturbation in multiple biological systems. The data have been deposited in ProteomeXchange with the identifier PXD000600.

Toxoplasma gondii cyclophilin 18 regulates the proliferation and migration of murine macrophages and spleen cells

Toxoplasma gondii is an intracellular parasite that shows a unique capacity to infect a variety of cell types in warm-blooded animals. It can invade and survive well inside immune cells, such as macrophages, that disseminate the parasite around the body because of their migratory properties. The aim of the present study was to evaluate the role of T. gondii cyclophilin 18 (TgCyp18) in the proliferation and migration of macrophages and spleen cells (mainly T lymphocytes) in order to understand the effects of TgCyp18 on the dynamics of the infection. A high dose of TgCyp18 enhanced the proliferation of macrophages and spleen cells in a cysteine-cysteine chemokine receptor 5 (CCR5)-independent way. In contrast, TgCyp18 controlled the migration of macrophages and spleen cells in dose- and CCR5-dependent manners. Our data suggest that TgCyp18 recruits cells and enhances the growth of host cells at the site of infection for maintenance of the interaction between the parasite and host.

Alcohol extracts of Echinacea inhibit production of nitric oxide and tumor necrosis factor-alpha by macrophages in vitro

It has been suggested that Echinacea has anti-inflammatory activity in vivo. Nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), and interleukin-1beta are important mediators in the inflammatory response. The effect of alcohol extracts of E. angustifolia (EA), E. pallida (EPA) and E. purpurea (EP) on the production of these inflammatory mediators in both LPS-stimulated RAW 264.7 macrophages in vitro and murine peritoneal exudate cells (PECs) in vivo were investigated. As macrophages produce these inflammatory mediators in response to pathogenic infection, parallel cultures of macrophages were studied for phagocytosis and intracellular killing of Salmonella enterica. EPA and EP in vitro inhibited NO production and TNF-α release in a dose-dependent manner. RAW 264.7 cells treated with EA or EP showed decreased killing over 24 h, although EA enhanced bacterial phagocytosis. Upon bacterial infection, RAW 264.7 cells produce high levels of NO; however, an Echinacea-mediated decrease in NO production was observed. Echinacea alcohol extracts administered orally at 130 mg/kg per day for seven days had a weak effect on NO production and phagocytosis by LPS-stimulated PECs. The results indicated that all Echinacea species significantly decreased inflammatory mediators in vitro, however, only EA and EP reduced bacterial killing. Oral administration of Echinacea alcohol extracts did not adversely affect the development and anti-bacterial function of inflammatory PECs in vivo, however, NO production was decreased during bacterial infection of PECs.

Lipopolysaccharide-induced sensitization of adenylyl cyclase activity in murine macrophages

LPS is known to modulate macrophage responses during sepsis, including cytokine release, phagocytosis, and proliferation. Although agents that elevate cAMP reverse LPS-induced macrophage functions, whether LPS itself modulates cAMP and whether LPS-induced decreases in proliferation are modulated via a cAMP-dependent pathway are not known. Murine macrophages (RAW264.7 cells) were treated with LPS in the presence or absence of inhibitors of prostaglandin signaling, protein kinases, CaM, Giproteins, and NF-κB translocation or transcription/translation. LPS effects on CaMKII phosphorylation and the expression of relevant adenylyl cyclase (AC) isoforms were measured. LPS caused a significant dose (5–10,000 ng/ml)- and time (1–8 h)-dependent increase in forskolin-stimulated AC activity that was abrogated by pretreatment with SN50 (an NF-κB inhibitor), actinomycin D, or cycloheximide, indicating that the effect is mediated via NF-κB-dependent transcription and new protein synthesis. Furthermore, LPS decreased the phosphorylation state of CaMKII, and pretreatment with a CaM antagonist attenuated the LPS-induced sensitization of AC. LPS, cAMP, or PKA activation each independently decreased macrophage proliferation. However, inhibition of NF-κB had no effect on LPS-induced decreased proliferation, indicating that LPS-induced decreased macrophage proliferation can proceed via PKA-independent signaling pathways. Taken together, these findings indicate that LPS induces sensitization of AC activity by augmenting the stimulatory effect of CaM and attenuating the inhibitory effect of CaMKII on isoforms of AC that are CaMK sensitive.

Prolonged exposure to intermittent alcohol vapors decreases the ACTH as well as hypothalamic nitric oxide and cytokine responses to endotoxemia

BACKGROUND

Prolonged exposure to alcohol blunts the response of the hypothalamic-pituitary-adrenal (HPA) axis to various stressors, including the systemic injection of a lipopolysaccharide (LPS). We previously showed that decreased synthesis of the hypothalamic peptides corticotropin-releasing factor (CRF) and vasopressin (VP) played a central role in this phenomenon. However, the mechanisms that lead to decreased hypothalamic neuronal activity have not been identified. In the present work, we tested the hypothesis that alcohol decreased signals that are elicited by LPS and that stimulate hypothalamic CRF and VP synthesis, namely nitric oxide (NO) and the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6).

METHODS

Adult male rats were exposed to intermittent (5 hr/day) alcohol vapors for 5 days. Control animals were kept in comparable chambers but not exposed to the vapors. On day 6, the animals received an injection of LPS through permanent indwelling intravenous cannulae. The dependent variables were plasma ACTH levels measured by IRMA (immunoradiometric assay); pituitary and hypothalamic TNF-alpha and IL-6 mRNA levels measured by RNase protection assay; basal activity of neuronal NO synthase measured by conversion of [14C]arginine to [14C]citrulline, the constitutive enzyme that synthesizes NO and modulates the influence of this gas on LPS-induced HPA axis activity; and basal and LPS-induced levels of citrulline (an index of NO formation) in the hypothalamus, measured by immunocytochemistry.

RESULTS

After injection with LPS, rats that were pretreated with alcohol exhibited a significantly (p < 0.01) decreased release of ACTH, compared with controls. There was no difference in basal NO synthase activity or hypothalamic citrulline levels. In contrast, LPS-induced hypothalamic citrulline levels were significantly (p < 0.01) lower in alcohol-exposed rats, as were pituitary TNF-alpha and IL-6 transcripts. In the hypothalamus, the TNF-alpha but not IL-6 response to LPS was also reduced.

CONCLUSIONS

These results indicate that prolonged exposure to alcohol decreases the ACTH, hypothalamic NO and TNF-alpha, and pituitary TNF-alpha and IL-6 responses to LPS. This suggests that altered NO and proinflammatory cytokine levels in the brain may modulate the inhibitory influence exerted by alcohol on the HPA axis response to endotoxemia.

Ethanol abuse and the trauma patient

BACKGROUND

Alcohol intoxication has long been associated with an increased risk of injury from a number of mechanisms and with trauma recidivism. It is less certain whether alcohol abuse is associated with worse outcomes for a given degree of injury.

METHODS

Review of the pertinent English-language literature.

RESULTS

The vasodilator effects of alcohol may hamper fluid resuscitation, especially in head-injured patients. Acute and chronic alcohol intoxication both have substantial effects on the cellular and molecular responses necessary to fight infection. High alcohol concentrations exert an immunosuppressive effect on production of proinflammatory cytokines such as tumor necrosis factor and interleukin-1. However, the clinical effects of the immunosuppression are variable and difficult to discern in heterogeneous trauma patient populations with variable degrees of intoxication.

CONCLUSION

Alcohol has a profound impact on the epidemiology of injury, but the physiology and biochemical effects in an individual patient may be difficult to predict. Identification of intoxicated persons is essential, despite economic disincentives to do so, because even brief targeted intervention programs can decrease substantially the patient's risk of subsequent injury.

Regulation of nitric oxide synthesis by dietary factors

Nitric oxide (NO) is synthesized from L-arginine by NO synthase (NOS). As an endothelium-derived relaxing factor, a mediator of immune responses, a neurotransmitter, a cytotoxic free radical, and a signaling molecule, NO plays crucial roles in virtually every cellular and organ function in the body. The discovery of NO synthesis has unified traditionally diverse research areas in nutrition, physiology, immunology, pathology, and neuroscience. Increasing evidence over the past decade shows that many dietary factors, including protein, amino acids, glucose, fructose, cholesterol, fatty acids, vitamins, minerals, phytoestrogens, ethanol, and polyphenols, are either beneficial to health or contribute to the pathogenesis of chronic diseases partially through modulation of NO production by inducible NOS or constitutive NOS. Although most published studies have focused on only a single nutrient and have generated new and exciting knowledge, future studies are necessary to investigate the interactions of dietary factors on NO synthesis and to define the underlying molecular mechanisms.