Lipopolysaccharide of Aggregatibacter actinomycetemcomitans induces the expression of chemokines MCP-1, MIP-1α, and IP-10 via similar but distinct signaling pathways in murine macrophages

Mechanisms underlying the effects, and clinical applications, of oral microbiota in lung cancer: current challenges and prospects

The oral cavity contains a site-specific microbiota that interacts with host cells to regulate many physiological processes in the human body. Emerging evidence has suggested that changes in the oral microbiota can increase the risk of lung cancer (LC), and the oral microbiota is also altered in patients with LC. Human and animal studies have shown that oral microecological disorders and/or specific oral bacteria may play an active role in the occurrence and development of LC through direct and/or indirect mechanisms. These studies support the potential of oral microbiota in the clinical treatment of LC. Oral microbiota may therefore be used in the prevention and treatment of LC and to improve the side effects of anticancer therapy by regulating the balance of the oral microbiome. Specific oral microbiota in LC may also be used as screening or predictive biomarkers. This review summarizes the main findings in research on oral microbiome-related LC and discusses current challenges and future research directions.

Salivary and serum nitric oxide synthase, macrophage inflammatory protein 1 alpha and macrophage migration inhibitory factor levels in periodontal disease

Objective

Periodontal disease is multifactorial inflammatory disease involving both gingivitis and periodontitis. Inducible nitric oxide synthase (iNOS), macrophage inflammatory protein 1 alpha (MIP-1α) and macrophage migration inhibitory factor (MIF) are mediators contributing to the progression of periodontal diseases with distinct functions. The aim of this study is to evaluate the local and systemic iNOS, MIP-1α and MIF concentrations in patients having periodontal disease with different severities.

Design

The study was conducted on 88 individuals equally divided into four groups; 1) Periodontally Healthy 2) Gingivitis 3) Stage I-II Periodontitis 4) Stage III-IV Periodontitis. Saliva and serum samples were obtained from each individual and then periodontal examinations were performed. Plaque and bleeding on probing indexes, probing depths and clinical attachment levels were measured on each tooth to determine the periodontal status. Concentrations of iNOS, MIP-1α and MIF were measured with enzyme-linked immunosorbent assay.

Results

Patients with stage I-II and stage III-IV periodontitis had more iNOS levels than periodontally healthy people in serum and saliva (p ≤ 0,001 for serum; p < 0,05 for saliva). Stage III-IV periodontitis group had significantly more serum-iNOS levels than that in gingivitis group (p = 0,005). When compared with periodontally healthy individuals, MIP-1α levels in stage III-IV periodontitis patients were measured significantly more in saliva; (p = 0,016) but less in serum (p = 0,006) samples. More serum-MIF concentrations were observed in stage I-II periodontitis groups than that in periodontally healthy individuals (p < 0,05).

Conclusion

Increased salivary and serum iNOS and serum-MIF levels in different stages of periodontitis suggest that these molecules might be involved in periodontal disease pathogenesis. Also, oral microenvironment may stimulate the enhanced MIP-1α concentration in advanced periodontitis cases.

Tannerella forsythia strains differentially induce interferon gamma-induced protein 10 (IP-10) expression in macrophages due to lipopolysaccharide heterogeneity

Tannerella forsythia is strongly implicated in the development of periodontitis, an inflammatory disease that destroys the bone and soft tissues supporting the tooth.  To date, the knowledge of the virulence attributes of T. forsythia species has mainly come from studies with a laboratory adapted strain (ATCC 43 037). In this study, we focused on two T. forsythia clinical isolates, UB4 and UB20, in relation to their ability to activate macrophages. We found that these clinical isolates differentially induced proinflammatory cytokine expression in macrophages. Prominently, the expression of the chemokine protein IP-10 (CXCL10) was highly induced by UB20 as compared to UB4 and the laboratory strain ATCC 43 037. Our study focused on the lipopolysaccharide component (LPS) of these strains and found that UB20 expressed a smooth-type LPS, unlike UB4 and ATCC 43 037 each of which expressed a rough-type LPS. The LPS from UB20, via activation of TLR4, was found to be a highly potent inducer of IP-10 expression via signaling through STAT1 (signal transducer and activator of transcription-1). These data suggest that pathogenicity of T. forsythia species could be strain dependent and the LPS heterogeneity associated with the clinical strains might be responsible for their pathogenic potential and severity of periodontitis.

Cellular distribution of C-C motif chemokine ligand 2 like immunoreactivities in frontal cortex and corpus callosum of normal and lipopolysaccharide treated animal

BACKGROUND

C-C motif chemokine ligand 2 (CCL2) is reported to be involved in the pathogenesis of various neurological and/or psychiatric diseases. Tissue or cellular expression of CCL2, in normal or pathological condition, may play an essential role in recruiting monocytes or macrophages into targeted organs, and be involved in a certain pathogenic mechanism. However, few studies focused on tissue and cellular distribution of the CCL2 peptide in brain grey and white matters (GM, WM), and the changes of the GM and WM cellular CCL2 level in septic or endotoxic encephalopathy was not explored. Hence, the CCL2 cellular distribution in the front brain cortex and the corpus callosum (CC) was investigated in the present work by using immunofluorescent staining.

RESULTS

(1) CCL2 like immunoreactivity (CCL2-ir) in the CC is evidently higher than the cortex. When the measurement includes ependymal layer attached to the CC, CCL2-ir intensity is significantly higher than cortex. (2) Structures in perivascular areas, most of them are GFAP positive, contribute major CCL2-ir positive profiles in both GM and WM, but apparently more in the CC, where they are bilaterally distributed in the lateral CC between the cingulate cortex and ventricles. (3) The neuron-like CCL2-ir positive cells in cortex are significantly more than in the CC, and that number is significantly increased in the cortex following systemic lipopolysaccharide (LPS), but not in the CC. (4) In addition to CCL2-ir positive perivascular rings, more CCL2-ir filled cashew shape elements are observed, probably inside of microvasculature, especially in the CC following systemic LPS. (5) Few macrophage/microglia marker-Iba-1 and CCL2-ir co-labeled structures especially the soma is found in normal cortex and CC; the co-localizations are significantly augmented following systemic LPS, and co-labeled amoeba like somata are presented. (6) CCL2-ir and astrocyte marker GFAP or Iba-1 double labeled structures are also observed within the ependymal layer. No accumulation of neutrophils was detected.

CONCLUSION

There exist differences in the cellular distribution of the CCL2 peptide in frontal cortex GM and subcortical WM-CC, in both the physiological condition and experimental endotoxemia. Which might cause different pathological change in the GM and WM.

Cordycepin Attenuates IFN-γ-Induced Macrophage IP-10 and Mig Expressions by Inhibiting STAT1 Activity in CFA-Induced Inflammation Mice Model

Cordycepin, a natural derivative of adenosine, has been shown to exert pharmacological properties including anti-oxidation, antitumor, and immune regulation. It is reported that cordycepin is involved in the regulation of macrophage function. However, the effect of cordycepin on inflammatory cell infiltration in inflammation remains ambiguous. In this study, we investigated the potential role of cordycepin playing in macrophage function in CFA-induced inflammation mice model. In this model, we found that cordycepin prevented against macrophage infiltration in paw tissue and reduced interferon-γ (IFN-γ) production in both serum and paw tissue. Using luciferase reporter assay, we found that cordycepin suppressed IFN-γ-induced activators of transcription-1 (STAT1) transcriptional activity in a dose-dependent manner. Moreover, western blotting data demonstrated that cordycepin inhibited IFN-γ-induced STAT1 activation through attenuating STAT1 phosphorylation. Further investigations revealed that cordycepin inhibited the expressions of IFN-γ-inducible protein 10 (IP-10) and monokine induced by IFN-γ (Mig), which were the effector genes in IFN-γ-induced STAT1 signaling. Meanwhile, the excessive inflammatory cell infiltration in paw tissue was reduced by cordycepin. These findings demonstrate that cordycepin alleviates excessive inflammatory cell infiltration through down-regulation of macrophage IP-10 and Mig expressions via suppressing STAT1 phosphorylation. Thus, cordycepin may be a potential therapeutic approach to prevent and treat inflammation-associated diseases.

Lipoteichoic acid of Enterococcus faecalis interferes with Porphyromonas gingivalis lipopolysaccharide signaling via IRAK-M upregulation in human periodontal ligament cells

Periodontitis is a chronic inflammatory disease of the gum caused by infection with multispecies oral bacteria. Since the periodontopathic bacteria, Porphyromonas gingivalis together with Enterococcus faecalis are frequently detected in patients with a severe form of periodontitis, interactions between their virulence factors might play an important role in progression of the disease. P. gingivalis and E. faecalis possess lipopolysaccharide (Pg.LPS) and lipoteichoic acid (Ef.LTA), respectively, as the major virulence factors inducing inflammatory responses. However, the combinatorial effect of these virulence factors on chemokine expression was poorly understood. Here, we examined the interaction between Ef.LTA and Pg.LPS on IL-8 induction in human periodontal ligament (PDL) cells. Pg.LPS, but not Ef.LTA, induced IL-8 expression at both mRNA and protein levels, which was suppressed in the presence of Ef.LTA. Although Ef.LTA and Pg.LPS could stimulate Toll-like receptor 2 (TLR2), Ef.LTA did not interfere with Pg.LPS induced-TLR2 activation. However, Ef.LTA decreased Pg.LPS-induced phosphorylation of ERK, JNK, and p38 kinase. Furthermore, Ef.LTA suppressed Pg.LPS-induced IL-8 promoter activity as well as AP-1, NF-IL6 and NF-κB transcription factors, which are indispensable for IL-8 expression. Interestingly, Ef.LTA enhanced only IL-1 receptor-associated kinase-M (IRAK-M) expression among the tested negative regulators of TLR intracellular signaling cascades in the presence of Pg.LPS. In addition, silencing IRAK-M restored the decreased IL-8 expression by Ef.LTA in the presence of Pg.LPS. Collectively, these results suggest that Ef.LTA inhibits Pg.LPS-induced IL-8 expression in human PDL cells via inducing the expression of a negative regulator of TLR signaling cascades, IRAK-M.

Salivary concentrations of macrophage activation-related chemokines are influenced by non-surgical periodontal treatment: a 12-week follow-up study

Background: During periodontal inflammation, bacteria induces chemokine expression and migration of various inflammatory cells. The aim of the study was to learn if periodontal treatment alters salivary concentrations of macrophage activation-related chemokines and if such alterations correlate with abundance of periodontitis-associated bacteria. Methods: Twenty-five patients with periodontitis completed the study (NCT02913248 at clinicaltrials.gov). Periodontal parameters and stimulated saliva samples were obtained at baseline and 2, 6 and 12 weeks after non-surgical periodontal treatment. Salivary concentrations of monocyte chemoattractant proteins (MCP-1-4), macrophage-derived chemokine (MDC), macrophage migration inhibitory factor (MIF), monokine induced by interferon-gamma (MIG), macrophage inflammatory protein (MIP-1α) and interferon-inducible protein (IP-10) were quantified using the Luminex® xMAP™ technique and abundance of bacteria was quantified using next-generation sequencing. Results: The treatment improved all periodontal parameters and caused an increase in the concentrations of MCP-2, MDC and MIP-1α at week 12 compared to baseline, week 2 and week 6, respectively. Salivary concentrations of MCP-1-2, MDC, MIG, MIP-1α and IP-10 correlated with the abundance of specific periodontitis-associated bacteria. Conclusions: Periodontal treatment impacts salivary concentrations of MCP-2, MDC and MIP-1α, which correlate with the abundance of specific periodontitis-associated bacteria. This indicates that these chemokines reflect periodontal status and possess potential in illustrating a response to treatment.

Virulence and Pathogenicity Properties of Aggregatibacter actinomycetemcomitans

Aggregatibacter actinomycetemcomitans is a periodontal pathogen colonizing the oral cavity of a large proportion of the human population. It is equipped with several potent virulence factors that can cause cell death and induce or evade inflammation. Because of the large genetic diversity within the species, both harmless and highly virulent genotypes of the bacterium have emerged. The oral condition and age, as well as the geographic origin of the individual, influence the risk to be colonized by a virulent genotype of the bacterium. In the present review, the virulence and pathogenicity properties of A. actinomycetemcomitans will be addressed.

Alveolar Macrophage Chemokine Secretion Mediates Neutrophilic Lung Injury in Nox2-Deficient Mice

Acute lung injury (ALI), developing as a component of the systemic inflammatory response syndrome (SIRS), leads to significant morbidity and mortality. Reactive oxygen species (ROS), produced in part by the neutrophil NADPH oxidase 2 (Nox2), have been implicated in the pathogenesis of ALI. Previous studies in our laboratory demonstrated the development of pulmonary inflammation in Nox2-deficient (gp91^phox-/y) mice that was absent in WT mice in a murine model of SIRS. Given this finding, we hypothesized that Nox2 in a resident cell in the lung, specifically the alveolar macrophage, has an essential anti-inflammatory role. Using a murine model of SIRS, we examined whole-lung digests and bronchoalveolar lavage fluid (BALf) from WT and gp91^phox-/y mice. Both genotypes demonstrated neutrophil sequestration in the lung during SIRS, but neutrophil migration into the alveolar space was only present in the gp91^phox-/y mice. Macrophage inflammatory protein (MIP)-1α gene expression and protein secretion were higher in whole-lung digest from uninjected gp91^phox-/y mice compared to the WT mice. Gene expression of MIP-1α, MCP-1, and MIP-2 was upregulated in alveolar macrophages obtained from gp91^phox-/y mice at baseline compared with WT mice. Further, ex vivo analysis of alveolar macrophages, but not bone marrow-derived macrophages or peritoneal macrophages, demonstrated higher gene expression of MIP-1α and MIP-2. Moreover, isolated lung polymorphonuclear neutrophils migrate to BALf obtained from gp91^phox-/y mice, further providing evidence of a cell-specific anti-inflammatory role for Nox2 in alveolar macrophages. We speculate that Nox2 represses the development of inflammatory lung injury by modulating chemokine expression by the alveolar macrophage.

Adiponectin Deficiency Triggers Bone Loss by Up-Regulation of Osteoclastogenesis and Down-Regulation of Osteoblastogenesis

Osteoporosis and bone disorders related to the metabolic syndrome are often associated with adipokines secreted by adipocytes in bone. Adiponectin, a type of adipokine, is a regulator of immune responses and metabolic processes, but its role in bone biology remains uncertain. We investigated the role of adiponectin in bone metabolism using adiponectin-deficient mice in vivo and in vitro. Adiponectin-deficient mice exhibited reduced bone mass and increased adiposity. Adiponectin-deficient calvarial cells were prone to differentiate into adipocytes rather than osteoblasts. Although bone marrow macrophages (BMMs) from adiponectin-deficient mice had low osteoclastogenic potential as osteoclast precursors with increasing interferon regulatory factor 5 expression, under co-culture conditions of calvarial cells and BMMs, the enhanced receptor activator of nuclear factor κB ligand/osteoprotegerin (RANKL/OPG) ratio of adiponectin-deficient mesenchymal progenitor cells facilitated osteoclast differentiation. In addition, increased RANKL/OPG ratio was observed in the bone marrow extracellular fluid of adiponectin-deficient mice compared to that of wild-type mice. Notably, recombinant adiponectin treatment enhanced RANKL-induced osteoclast differentiation from BMMs but up-regulated OPG production in recombinant adiponectin-exposed calvarial cells, which inhibited osteoclast differentiation. Taken together, these results suggest that adiponectin plays an inhibitory role in bone metabolism through cross talk between precursor cells of both osteoclasts and osteoblasts by regulating RANKL/OPG ratio in the bone marrow microenvironment.

IFN-β Plays Both Pro- and Anti-inflammatory Roles in the Rat Cardiac Fibroblast Through Differential STAT Protein Activation

Cardiac fibroblasts (CFs) contribute to theinflammatory response to tissue damage, secreting both pro- and anti-inflammatory cytokines and chemokines. Interferon beta (IFN-β) induces the phosphorylation of signal transducer and activator of transcription (STAT) proteins through the activation of its own receptor, modulating the secretion of cytokines and chemokines which regulate inflammation. However, the role of IFN-β and STAT proteins in modulating the inflammatory response of CF remains unknown. CF were isolated from adult male rats and subsequently stimulated with IFN-β to evaluate the participation of STAT proteins in secreting chemokines, cytokines, cell adhesion proteins expression and in their capacity to recruit neutrophils. In addition, in CF in which the TRL4 receptor was pre-activated, the effect of INF-β on the aforementioned responses was also evaluated. Cardiac fibroblasts stimulation with IFN-β showed an increase in STAT1, STAT2, and STAT3 phosphorylation. IFN-β stimulation through STAT1 activation increased proinflammatory chemokines MCP-1 and IP-10 secretion, whereas IFN-β induced activation of STAT3 increased cytokine secretion of anti-inflammatory IL-10. Moreover, in TLR4-activated CF, IFN-β through STAT2 and/or STAT3, produced an anti-inflammatory effect, reducing pro-IL-1β, TNF-α, IL-6, MCP-1, and IP-10 secretion; and decreasing neutrophil recruitment by decreasing ICAM-1 and VCAM-1 expression. Altogether, our results indicate that IFN-β exerts both pro-inflammatory and anti-inflammatory effects in non-stimulated CF, through differential activation of STAT proteins. When CF were previously treated with an inflammatory agent such as TLR-4 activation, IFN-β effects were predominantly anti-inflammatory.

Levels of Pro and Anti-inflammatory Citokynes and C-Reactive Protein in Patients with Chronic Periodontitis Submitted to Nonsurgical Periodontal Treatment

Aim

to compare the levels of IFN-γ, TGF-β and C-reactive protein (CRP) in healthy patients (HP) and chronic periodontitis patients (CP) before and seven days after the last session of Non-Surgical Periodontal Treatment (NSPT).

Materials and Methods

40 subjects were divided into two groups: healthy (n= 20), and with chronic periodontitis (n = 20). Serum and gingival crevicular fluid (GCF) were collected from each patient and quantified for IFN-γ, TGF-β and CRP using the enzyme-linked immunosorbent assay (ELISA).

Results

IFN-γ was found to be higher in the GCF of the CP group before NSPT in relation to the HP group (p<0.05), and it had significant higher levels after seven days of NSPT (p<0.05). The levels of TGF-β in the GCF of CP patients before NSPT were significantly higher when compared to HP (p<0.05), but they decreased after seven days of NSPT (p>0.05). Serum CRP levels did not show statistical difference between CP and HP before or after NSPT.

Conclusion

Therefore, our results demonstrated for the first time that NSPT causes early exacerbation of the immune response at the local level represented by increased levels of IFN-γ and decreased levels of TGF-β in the gingival crevicular fluid after seven days of treatment.

Porphyromonas gingivalis lipopolysaccharide induces over production of CC chemokine ligand 2 via toll-like receptor-4 in oral lichen planus

BACKGROUND

We recently reported that the CC chemokine ligand 2 (CCL2)-CC receptor 2 (CCR2) axis was involved in the pathogenesis of oral lichen planus (OLP). However, the exact mechanism for the high expression of CCL2 in OLP specimens is not clear. Therefore, this study was designed to investigate the potential role of the toll-like receptor 4 (TLR-4) pathway in overproduction of CCL2 in OLP lesions.

METHODS

Immunohistochemical staining and real-time RT-PCR were used to detect TLR-4, CCL2, and CCR2 expression in OLP lesions. Then, gingival epithelial cells from OLP lesions were established and treated with Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS). CCL2 expression in epithelial cells was determined by Western blotting and real-time RT-PCR. In some experiments, TAK-242, a specific inhibitor of TLR-4, was used to block the TLR-4 pathway before cells were stimulated with LPS.

RESULTS

We found that TLR-4 was significantly increased in the epithelium of OLP specimens, compared with controls. Moreover, LPS can induce the over production of CCL2 in epithelial cells of OLP, in vitro. TAK-242 effectively eliminated the increase in CCL2 expression induced by LPS by blocking the TLR-4/NF-κB pathway. In addition, we again confirmed that expression of CCL2 and CCR2 was increased in OLP specimens.

CONCLUSION

Increased TLR-4 expression contributes to the upregulated expression of CCL2 in the epithelium of OLP lesions, which suggests that oral bacteria participate in the pathogenesis of OLP via the TLR-4 pathway.

The deposition of anti-DNA IgG contributes to the development of cutaneous lupus erythematosus

Anti-DNA IgG is a hallmark of systemic lupus erythematosus and induces internal injuries in patients. It is known that cutaneous lupus erythematosus (CLE) involves the deposition of autoantibodies in the dermoepidermal junction of the skin and that anti-DNA IgG binds specifically to keratinocytes. However, the definite role of anti-DNA IgG in CLE remains unclear. The purpose of this study was to elucidate the effect of anti-DNA IgG on keratinocytes in CLE. Skin tissues were collected from patients with CLE and healthy controls. Also, murine anti-DNA IgG was incubated with frozen sections of murine skin or PAM212 keratinocytes. The chemotaxis of J774.2 macrophages was evaluated in special chambers with keratinocytes under anti-DNA IgG stimulation. Enzyme-linked immunosorbent assay, flow cytometry, Western blot, and surface plasmon resonance were used to quantitate the interaction between anti-DNA IgG and keratinocyte-related self-antigens. The results showed that anti-DNA IgG could be eluted from the lesional tissues of CLE patients, depending on the serum positivity. Murine anti-DNA IgG bound preferably to the dermoepidermal zones of normal skin and specifically to collagen III and the suppressor of cytokine signalling 1 (SOCS1) but not to Ro52. Moreover, the chemotaxis of macrophages was promoted by the incubation of anti-DNA IgG with keratinocytes. Interestingly, anti-DNA IgG exaggerated both the expression and the activation of fibroblast growth factor inducible 14 (Fn14) in keratinocytes and regulated SOCS1 signals in a time-dependent manner. In conclusion, anti-DNA IgG may contribute to the development of CLE through binding to keratinocyte-related antigens, exacerbating inflammatory infiltration, and modulating Fn14 and SOCS1 pathways.

Wu-Tou Decoction in Rheumatoid Arthritis: Integrating Network Pharmacology and In Vivo Pharmacological Evaluation

Purpose: This study aimed to explore underlying action mechanism of Wu-Tou decoction (WTD) in rheumatoid arthritis (RA) through network pharmacology prediction and experimental verification. Methods: Chemical compounds and human target proteins of WTD as well as RA-related human genes were obtained from TCM Database @ Taiwan, PubChem and GenBank, respectively. Subsequently, molecular networks and canonical pathways presumably involved in the treatment of WTD on RA were generated by ingenuity pathway analysis (IPA) software. Furthermore, experimental validation was carried out with MIP-1β-induced U937 cell model and collagen induced arthritis (CIA) rat model. Results: CCR5 signaling pathway in macrophages was shown to be the top one shared signaling pathway associated with both cell immune response and cytokine signaling. In addition, protein kinase C (PKC) δ and p38 in this pathway were treated as target proteins of WTD in RA. In vitro experiments indicated that WTD inhibited MIP-1β-induced production of TNF-α, MIP-1α, and RANTES as well as phosphorylation of CCR5, PKC δ, and p38 in U937 cells. WTD treatment maintained the inhibitory effects on production of TNF-α and RANTES in MIP-1β-induced U937 cells after CCR5 knockdown. In vivo experiments demonstrated that WTD ameliorated symptoms in CIA rats, decreased the levels of IL-1β, IL-2, IL-6, TNF-α, MIP-1α, MIP-2, RANTES, and IP-10 in serum of CIA rats, as well as mRNA levels of MIP-1α, MIP-2, RANTES, and IP-10 in ankle joints of CIA rats. Furthermore, WTD also lowered the phosphorylation levels of CCR5, PKC δ and p38 in both ankle joints and macrophages in ankle joints from CIA rats. Conclusion: It was demonstrated in this research that WTD played a role in inhibiting inflammatory response in RA which was closely connected with the modulation effect of WTD on CCR5 signaling pathway in macrophages.

Molecular impact of omega 3 fatty acids on lipopolysaccharide-mediated liver damage

BACKGROUND

Growing evidence suggests that omega 3 fatty acid containing lipid emulsions have a beneficial effect on parenteral nutrition associated liver disease (PNALD). However, the cellular and molecular mechanisms responsible for this effect are unclear. In this study, we investigated whether Omegaven™ fish oil emulsion could inhibit lipopolysaccharidase (LPS) mediated liver damage.

METHODS

We examined the effects of Omegaven™ and LPS alone and synergistically on hepatic paraoxonase 1 (PON1), a potent antioxidant protein, ERK1/2 activity, and TLR4 regulation.

RESULTS

LPS did not alter PON1 release from HepG2 cells but did significantly decrease PON1 protein synthesis (44%, P<0.05). Omegaven™ alone had no direct effect on PON1 release. However, it did significantly reverse LPS-mediated decrease in PON1 protein levels (control: 100%; LPS alone: 56+/4%; LPS+Omegaven™: 87+/6%, P<0.05). Furthermore, molecular analysis indicated that Omegaven™ blocked LPS-mediated increase in ERK1/2 activity (35% increase), an important LPS signal transduction pathway. TLR4, the receptor for LPS, was down-regulated in the presence of Omegaven™.

CONCLUSION

Omegaven™ may be beneficial in patients with PNAC because of its ability to reverse LPS-mediated inhibition of antioxidant promoting PON1 expression, and this activity may be in part mediated by the ERK1/2 pathway.

The Dietary Isoflavone Daidzein Reduces Expression of Pro-Inflammatory Genes through PPARα/γ and JNK Pathways in Adipocyte and Macrophage Co-Cultures

Obesity-induced inflammation caused by adipocyte-macrophage interactions plays a critical role in developing insulin resistance, and peroxisome proliferator-activated receptors (PPARs) regulate inflammatory gene expression in these cells. Recently, the soy isoflavone daidzein was reported to act as a PPAR activator. We examined whether daidzein affected adipocyte-macrophage crosstalk via the regulation of PPARs. Co-cultures of 3T3-L1 adipocytes and RAW264 macrophages, or palmitate-stimulated RAW264 macrophages were treated with daidzein in the presence or absence of specific inhibitors for PPARs: GW6471 (a PPARα antagonist), and GW9662 (a PPARγ antagonist). Inflammatory gene expression was then determined. Daidzein significantly decreased chemokine (C-C motif) ligand 2 (Ccl2, known in humans as monocyte chemo-attractant protein 1 (MCP1)) and interleukin 6 (Il6) mRNA levels induced by co-culture. In 3T3-L1 adipocytes, daidzein inversed the attenuation of adiponectin gene expression by co-culture, and these effects were inhibited by the PPAR-γ specific inhibitor. Daidzein also decreased Ccl2 and Il6 mRNA levels in RAW264 macrophages stimulated with palmitate or conditioned medium (CM) from hypertrophied 3T3-L1 adipocytes. This inhibitory effect on Il6 expression was abrogated by a PPAR-α inhibitor. Additionally, we examined the activation of nuclear factor-kappa B (NF-κB) and c-Jun N-terminal kinase (JNK) pathways and found that daidzein significantly inhibited palmitate-induced phosphorylation of JNK. Our data suggest that daidzein regulates pro-inflammatory gene expression by activating PPAR-α and -γ and inhibiting the JNK pathway in adipocyte and macrophage co-cultures. These effects might be favorable in improving adipose inflammation, thus, treatment of daidzein may be a therapeutic strategy for chronic inflammation in obese adipose tissue.