Murine TOLL-like receptor 4 confers lipopolysaccharide responsiveness as determined by activation of NF kappa B and expression of the inducible cyclooxygenase

Importance of Fecal Microbiota Transplantation and Molecular Regulation as Therapeutic Strategies in Inflammatory Bowel Diseases

Noncoding RNAs, particularly microRNAs (miRNAs) and small interfering RNAs (siRNAs), have emerged as key players in the pathogenesis and therapeutic strategies for inflammatory bowel disease (IBD). MiRNAs, small endogenous RNA molecules that silence target mRNAs to regulate gene expression, are closely linked to immune responses and inflammatory pathways in IBD. Notably, miR-21, miR-146a, and miR-155 are consistently upregulated in IBD, influencing immune cell modulation, cytokine production, and the intestinal epithelial barrier. These miRNAs serve as biomarkers for disease progression and severity, as well as therapeutic targets for controlling inflammation. This comprehensive review highlights the intricate interplay between the gut microbiota, fecal microbiota transplantation (FMT), and miRNA regulation. It concludes that microbiota and FMT influence miRNA activity, presenting a promising avenue for personalized IBD treatment.

Toll-like receptor 4: A potential therapeutic target for multiple human diseases

The immune response plays a pivotal role in the pathogenesis of diseases. Toll-like receptor 4 (TLR4), as an intrinsic immune receptor, exhibits widespread in vivo expression and its dysregulation significantly contributes to the onset of various diseases, encompassing cardiovascular disorders, neoplastic conditions, and inflammatory ailments. This comprehensive review centers on elucidating the architectural and distributive characteristics of TLR4, its conventional signaling pathways, and its mode of action in diverse disease contexts. Ultimately, this review aims to propose novel avenues and therapeutic targets for clinical intervention.

Evaluation of Immune Modulation by β-1,3; 1,6 D-Glucan Derived from Ganoderma lucidum in Healthy Adult Volunteers, A Randomized Controlled Trial

Fungi-derived β-glucan, a type of glucopolysaccharide, has been shown to possess immune-modulatory properties in clinical settings. Studies have indicated that β-glucan derived from Ganoderma lucidum (commonly known as Reishi) holds particular promise in this regard, both in laboratory and in vivo settings. To further investigate the efficacy and safety of Reishi β-glucan in human subjects, a randomized, double-blinded, placebo-controlled clinical trial was conducted among healthy adult volunteers aged 18 to 55. Participants were instructed to self-administer the interventions or placebos on a daily basis for 84 days, with bloodwork assessments conducted at the beginning and end of the study. The results of the trial showed that subjects in the intervention group, who received Reishi β-glucan, exhibited a significant enhancement in various immune cell populations, including CD3+, CD4+, CD8+ T-lymphocytes, as well as an improvement in the CD4/CD8 ratio and natural killer cell counts when compared to the placebo group. Additionally, a statistically significant difference was observed in serum immunoglobulin A levels and natural killer cell cytotoxicity between the intervention and placebo groups. Notably, the intervention was found to be safe and well tolerated, with no statistically significant changes observed in markers of kidney or liver function in either group. Overall, the study provides evidence for the ability of Reishi β-glucan to modulate immune responses in healthy adults, thereby potentially bolstering their defense against opportunistic infections.

Transcriptional regulation of Acsl1 by CHREBP and NF-kappa B in macrophages during hyperglycemia and inflammation

Acyl-CoA synthetase 1 (ACSL1) is an enzyme that converts fatty acids to acyl-CoA-derivatives for lipid catabolism and lipid synthesis in general and can provide substrates for the production of mediators of inflammation in monocytes and macrophages. Acsl1 expression is increased by hyperglycemia and inflammatory stimuli in monocytes and macrophages, and promotes the pro-atherosclerotic effects of diabetes in mice. Yet, surprisingly little is known about the mechanisms underlying Acsl1 transcriptional regulation. Here we demonstrate that the glucose-sensing transcription factor, Carbohydrate Response Element Binding Protein (CHREBP), is a regulator of the expression of Acsl1 mRNA by high glucose in mouse bone marrow-derived macrophages (BMDMs). In addition, we show that inflammatory stimulation of BMDMs with lipopolysaccharide (LPS) increases Acsl1 mRNA via the transcription factor, NF-kappa B. LPS treatment also increases ACSL1 protein abundance and localization to membranes where it can exert its activity. Using an Acsl1 reporter gene containing the promoter and an upstream regulatory region, which has multiple conserved CHREBP and NF-kappa B (p65/RELA) binding sites, we found increased Acsl1 promoter activity upon CHREBP and p65/RELA expression. We also show that CHREBP and p65/RELA occupy the Acsl1 promoter in BMDMs. In primary human monocytes cultured in high glucose versus normal glucose, ACSL1 mRNA expression was elevated by high glucose and further enhanced by LPS treatment. Our findings demonstrate that CHREBP and NF-kappa B control Acsl1 expression under hyperglycemic and inflammatory conditions.

MicroRNAs in Inflammatory Bowel Disease and Its Complications

Inflammatory bowel disease (IBD), classified primarily between Crohn's disease and ulcerative colitis, is a collection of chronic gastrointestinal inflammatory conditions that cause multiple complications because of systemic alterations in the immune response. One major player is microRNA (miRNA), which is found to be associated with multiple pathways in mediating inflammation, especially those of a chronic nature in IBD, as well as irritable bowel syndrome. Although there have been studies linking miRNA alterations in IBD, even differentiating Crohn's disease and ulcerative colitis, this review focuses mainly on how miRNAs cause and mechanistically influence the pathologic complications of IBD. In addition to its role in the well-known progression towards colorectal cancer, we also emphasize how miRNA manifests the many extraintestinal complications in IBD such as cardiovascular diseases; neuropsychiatric conditions such as depression and anxiety disorders; and others, including various musculoskeletal, dermatologic, ocular, and hepatobiliary complications. We conclude through a description of its potential use in bettering diagnostics and the future treatment of IBD and its systemic symptoms.

Antioxidant and Anti-Inflammatory Activity of Combined Phycocyanin and Palmitoylethanolamide in Human Lung and Prostate Epithelial Cells

Inflammation involving the innate and adaptive immune systems is a normal response to infection; however, when allowed to continue unchecked, inflammation may result in several pathologies. Natural molecules with antioxidant properties can target the key players of inflammation and exert beneficial health effects. In this study, human normal bronchial (Beas-2B) and prostate (HPrEpiC) epithelial cell lines were exposed to infectious stimulation and treated with phycocyanin (PC) and palmitoylethanolamide (PEA), with the aim of demonstrating the enhanced antioxidant and anti-inflammatory properties of the combination. The cotreatment protected from cytotoxicity and greatly abated both the production of radical oxygen species (ROS) and the transcription of several inflammatory cytokines. Oxidative stress and inflammation were curtailed by affecting three main pathways: (1) inhibition of cyclooxygenase-2 enzyme and consequent decrease of signaling generating ROS; (2) increased synthesis of glutathione and therefore strengthening of the natural antioxidant defenses of the cells; (3) decreased infection-driven mitochondrial respiratory burst which generates oxidative stress. Based on the mounting interest in using nutraceuticals as adjuvants in the clinical practice, the present study unveils new mechanisms of action and enhanced efficacy of PC and PEA, supporting the possible exploitation of this combination in human disorders.

Hesperetin suppresses LPS/high glucose-induced inflammatory responses via TLR/MyD88/NF-κB signaling pathways in THP-1 cells

BACKGROUND/OBJECTIVES

Unregulated inflammatory responses caused by hyperglycemia may induce diabetes complications. Hesperetin, a bioflavonoid, is a glycoside in citrus fruits and is known to have antioxidant and anticarcinogenic properties. However, the effect of inflammation on the diabetic environment has not been reported to date. In this study, we investigated the effect of hesperetin on proinflammatory cytokine secretion and its underlying mechanistic regulation in THP-1 macrophages with co-treatment LPS and hyperglycemic conditions.

MATERIALS/METHODS

THP-1 cells differentiated by PMA (1 μM) were cultured for 48 h in the presence or absence of hesperetin under normoglycemic (5.5 mM/L glucose) or hyperglycemic (25 mM/L glucose) conditions and then treated with LPS (100 ng/mL) for 6 h before harvesting. Inflammation-related proteins and mRNA levels were evaluated by enzyme-linked immunosorbent assay, western blot, and quantitative polymerase chain reaction analyses.

RESULTS

Hesperetin (0-100 μM, 48 h) treatment did not affect cell viability. The tumor necrosis factor-α and interleukin-6 levels increased in cells co-treated with LPS under hyperglycemic conditions compared to normoglycemic conditions, and these increases were decreased by hesperetin treatment. The TLR2/4 and MyD88 activity levels increased in cells co-treated with LPS under hyperglycemic conditions compared to normoglycemic conditions; however, hesperetin treatment inhibited the TLR2/4 and MyD88 activity increases. In addition, nuclear factor-κB (NF-κB) and Acetyl-NF-κB levels increased in response to treatment with LPS under hyperglycemic conditions compared to normoglycemic conditions, but those levels were decreased when treated with hesperetin. SIRT3 and SIRT6 expressions were increased by hesperetin treatment.

CONCLUSIONS

Our results suggest that hesperetin may be a potential agent for suppressing inflammation in diabetes.

Effect of rosiglitazone on developmental competence of mouse embryos treated with lipopolysaccharide

Lipopolysaccharide (LPS) significantly reduces pre- and post-implantation developmental competence of embryos. One of the reason of this effect could be a consequence of TLR4-mediated inflammation. In this study, we assessed the anti-inflammatory effect of peroxisome proliferator activated receptor γ (PPAR γ) agonist, rosiglitazone (RGZ), in LPS-treated mouse embryos. Initially, the optimal doses of LPS, RGZ and GW9662 (a potent and selective PPARγ antagonist) were determined by treating the mouse zygotes up to blastocyst stage and assessment of compaction and blastocyst rates. Quantitative PCR was used to assess the mRNA expression of inflammatory cytokines. Immunostaining was used to study the translocation of PPARγ in blastocysts. Finally, the blastocysts were transferred to surrogate mouse to determine the post-implantation developmental competence. 0.0625 mg/mL of LPS significantly reduced the developmental competency by around 50% compared to control group. 10 μM of RGZ significantly ameliorated the toxic effect of LPS, which was also significantly reversed by 1.25 μM GW9662. Through immunostaining, it was shown that LPS could prevent the translocation of PPARγ to nucleus; and translocation was facilitated by RGZ and this effect was reversed by GW9662. A similar effect was also observed for the mRNA expression of inflammatory cytokines (Il-1β and Il-6). LPS significantly increased the expression of these cytokines, while RGZ significantly reduced their expression, which was also significantly reversed by GW9662. It was also shown that embryos exposed to LPS had significantly reduced post implantation developmental competence which was considerably improved by treatment with RGZ. In conclusion, these data may have clinical implications for ameliorating the adverse effects of LPS in dairy farming and infertility treatment.

Autotaxin loss accelerates intestinal inflammation by suppressing TLR4-mediated immune responses

Autotaxin (ATX) converts lysophosphatidylcholine and sphingosyl-phosphorylcholine into lysophosphatidic acid and sphingosine 1-phosphate, respectively. Despite the pivotal function of ATX in lipid metabolism, mechanisms by which ATX regulates immune and inflammatory disorders remain elusive. Here, using myeloid cell lineage-restricted Atx knockout mice, we show that Atx deficiency disrupts membrane microdomains and lipid rafts, resulting in the inhibition of Toll-like receptor 4 (TLR4) complex formation and the suppression of adaptor recruitment, thereby inhibiting TLR4-mediated responses in macrophages. Accordingly, TLR4-induced innate immune functions, including phagocytosis and iNOS expression, are attenuated in Atx-deficient macrophages. Consequently, Atx^-/- mice exhibit a higher bacterial prevalence in the intestinal mucosa compared to controls. When combined with global Il10^-/- mice, which show spontaneous colitis due to the translocation of luminal commensal microbes into the mucosa, myeloid cell lineage-restricted Atx knockout accelerates colitis development compared to control littermates. Collectively, our data reveal that Atx deficiency compromises innate immune responses, thereby promoting microbe-associated gut inflammation.

Cyclooxygenase-2 Inhibition Reduces Autophagy of Macrophages Enhancing Extraintestinal Pathogenic Escherichia coli Infection

Extraintestinal pathogenic Escherichia coli (ExPEC) is one of the top pathogens responsible for bloodstream infection and severe, often fatal, sepsis. Although the virulence factors and host immune responses to ExPEC infection have been investigated, the responses to a particular ExPEC strain could be very different. In this study, we investigated the mechanisms of Cyclooxygenase-2 (COX-2) up-regulation in influencing the host defenses against infection of ExPEC XM O2:K1:H7. Our results demonstrated that ExPEC XM O2:K1:H7 infection in mouse and RAW264.7 macrophages leads to COX-2 up-regulation, and COX-2 inhibition significantly enhances ExPEC infection. The up-regulation of COX-2 in macrophages was mediated by Toll-like receptor 4 (TLR4) through the activation of p38 and extracellular signal-regulated kinase/Mitogen-activated protein kinase (ERK/MAPK) pathways. Further studies showed that COX-2 inhibition significantly decreased autophagy in macrophages during ExPEC XM O2:K1:H7 infection. Autophagy inhibition significantly enhanced, while induction reduced ExPEC XM O2:K1:H7 survival in macrophages. In addition, COX-2 inhibition significantly increased macrophage cell death during ExPEC XM O2:K1:H7 infection and increased the expression of anti-inflammatory cytokine interleukin-10 (IL-10). Our results indicate that COX-2 up-regulation benefits host defense against ExPEC XM O2:K1:H7 infection by increasing autophagy in macrophages and by reducing IL-10 expression and macrophage cell death during ExPEC infection.

TLR2/4 promotes PGE2 production to increase tissue damage in Escherichia coli-infected bovine endometrial explants via MyD88/p38 MAPK pathway

Prostaglandin E2 (PGE₂), a lipid mediator, is released by several cell types including endometrial cells and plays a central role in bacterial infection of the endometrium during inflammation. PGE₂ production accumulated in Escherichia coli (E. coli) -infected bovine endometrial tissue, which increased E. coli-infected endometrial tissue damage. However, the mechanisms of PGE₂ accumulation in the E. coli-infected endometrium during inflammation-associated endometrial tissue damage remain unclear. This study was conducted to investigate the role of Toll-like receptors (TLRs) 2 and 4 in increased PGE₂ production in E. coli-infected endometrial tissue. E. coli and TLR2/4 agonists significantly induced cyclooxygenase-2 and microsomal prostaglandin E synthase-1 expression and PGE₂ synthesis detected by RT-PCR, Western blot, and ELISA in the endometrial tissue. The expression and synthesis were dramatically decreased by TLR4, myeloid differentiation factor88 (MyD88), and p38 mitogen-activated protein kinase (MAPK) inhibitors in E. coli-infected endometrial tissue. These inhibitors also significantly decreased proinflammatory factor (interleukin-6 and tumor necrosis factor-α) and damage-associated molecular pattern (high mobility group box-1 and hyaluronan-binding protein-1) release and tissue damage measured by double-label immunofluorescence in E. coli-infected endometrial explants. Our work provides in vitro evidence that TLR2/4-MyD88/p38 MAPK promotes PGE₂ synthesis and E. coli-infected endometrial tissue damage, which may be useful for improving PGE₂-based therapies for endometritis.

β-Arrestin-2-ERK1/2 cPLA2α axis mediates TLR4 signaling to influence eicosanoid induction in ischemic brain

LPS has been shown to elicit neuroinflammation associated with the up-regulation of the eicosanoid pathway in animal models; however, the regulatory mechanisms of TLR4 in brain neuroinflammatory conditions remain elusive. β-Arrestins are key regulators of the GPCR signaling pathway and are involved in the leukotriene B4-induced leukocyte migration to initiate inflammatory response. However, the roles of β-arrestins in eicosanoid regulation and related diseases are not clear. To address this issue, we conducted a study to investigate the effect of TLR4 on the eicosanoid pathway in ischemic stroke brain and to explore the underlying molecular regulation mechanism. Cerebral ischemia was produced by occlusion of the middle cerebral artery, followed by reperfusion for 24 h. We demonstrated that knockout of TLR4 improves ischemic stroke brain associated with eicosanoid down-regulation. Interestingly, genetic disruption of β-arrestin-2 failed to decrease neuroinflammation in the damaged brain of TLR4^-/- mice, which indicates the requirement of β-arrestin-2 for TLR4 knockdown protection. Further study showed that the negative regulation of phosphorylated (phospho-)ERK1/2 and phospho-cytosolic phospholipase A₂ α (cPLA₂α) by TLR4 deficiency was eliminated by genetic disruption of β-arrestin-2. In addition, β-arrestin-2 deficiency reversed the reduction of colocalization of phospho-ERK1/2 with phospho-cPLA₂α in TLR4^-/- mice following ischemic stroke. Mechanistic studies indicated that β-arrestin-2 specifically colocalized and associated with ERK1/2 to prevent ERK1/2-dependent cPLA₂α activation following ischemic injury, and β-arrestin-2 deficiency blocked the negative regulation of phospho-ERK1/2, revived the association of phospho-ERK1/2 with phospho-cPLA₂α, and subsequently increased the prostaglandin E2 and thromboxane A2 production remarkably. Our findings may provide novel insights that β-arrestin-2 is responsible for ischemic brain improvement in TLR4^-/- mice via negative regulation of eicosanoid production.-Xiang, Y., Wei, X., Du, P., Zhao, H., Liu, A., Chen, Y. β-Arrestin-2-ERK1/2 cPLA₂α axis mediates TLR4 signaling to influence eicosanoid induction in ischemic brain.

Isolation of polysaccharides from Dendrobium officinale leaves and anti-inflammatory activity in LPS-stimulated THP-1 cells

Dendrobium officinale stem is rich in polysaccharides, which play a great role in the medicinal effects of this plant. However, little was known about the polysaccharides from Dendrobium officinale leaves. Two kinds of polysaccharides in the leaves, DLP-1 and DLP-2, were obtained by hot water extraction, alcohol sedimentation and chromatographic separation (DEAE-52 cellulose column and Sephadex G-100 column). The average molecular weights were determined as 28,342 Da and 41,143 Da, respectively. Monosaccharide compositions were analyzed using gas chromatography–mass spectrometer. DLP-1 was composed of d-(+)-galactose, dl-arabinose, and l-(+)-rhamnose with a molar ratio of 3.21:1.11:0.23, and traces of d-xylose, d-glucose, and d-(+)-mannose. DLP-2 was consisted of d-glucose and d-(+)-galactose with a molar ratio of 3.23:1.02, and traces of d-xylose, dl-arabinose. Then, we established inflammatory cell model by LPS acting THP-1 cells to investigate the anti-inflammatory effects of DLP-1 and DLP-2. The results indicated that DLP-1 (5 μg/mL) and DLP-2 (50 μg/mL) were effective in protecting THP-1 cells from LPS-stimulated cytotoxicity, as well as inhibiting reactive oxygen species formation. In addition, both DLP-1 (5 μg/mL) and DLP-2 (50 μg/mL) significantly suppressed toll-like receptor-4 (TLR-4), myeloid differentiation factor (MyD88) and tumour necrosis factor receptor-associated factor-6 (TRAF-6) mRNA and protein expression in LPS-stimulated THP-1 cells.

Preventive effects of bovine colostrum supplementation in TNBS-induced colitis in mice

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder for which the current medical therapy is not completely effective. Bovine colostrum (BC) is a biological fluid rich in bioactive molecules that may have beneficial effects on several gastrointestinal disorders. The objectives of this study were to assess the preventive effects of BC supplementation in a mouse model of 2,4,6 trinitrobenzene sulfonic acid (TNBS)-induced colitis using a multidisciplinary approach. Specifically, the following parameters were evaluated: (i) disease activity index (DAI), (ii) histological score, (iii) expression levels of TLR4, anti- and pro-inflammatory cytokines, and (iv) count of some bacterial species of the intestinal microbiota. Mice received a daily suspension of BC (BC group, n = 12) or saline solution (control, CN group, n = 12) for 21 days before the intrarectal inoculation with 1% of TNBS solution. BC was well tolerated and did not induce any histological damage or clinical symptoms. After TNBS treatment, BC group showed a reduction of body weight (BW) loss (P<0.01) and histological score (P<0.05) compared to CN. Moreover, the expression levels of TLR4 (P<0.05), IL-1β (P<0.001), IL-8 (P<0.001), and IL-10 (P<0.001) were lower in mice administered with BC, while the concentrations of TNF-α did not show any differences between groups. Finally, the supplementation with BC resulted in a differential response to TNBS treatment in the bacterial count. In CN group, E. coli and Enterococci increased (P<0.001), while Anaerobes (P<0.01), Lactobacilli, and Bifidobacteria (P<0.001) reduced. Conversely, no significant changes in bacterial load were found after the inoculation of TNBS in BC pre-treated mice. This study confirms that TNBS-induced colitis model in mice is useful for studying the mechanisms involved in IBD pathogenesis and shows that pre-treatment with BC reduces the intestinal damages and clinical signs of the colitis. Molecular mechanisms and intestinal microflora could be involved in the protective effect of colostrum.

TLR4 modulates inflammatory gene targets in the retina during Bacillus cereus endophthalmitis

Background

Endophthalmitis is a serious intraocular infection that frequently results in significant inflammation and vision loss. Because current therapeutics are often unsuccessful in mitigating damaging inflammation during endophthalmitis, more rational targets are needed. Toll-like receptors (TLRs) recognize specific motifs on invading pathogens and initiate the innate inflammatory response. We reported that TLR4 contributes to the robust inflammation which is a hallmark of Bacillus cereus endophthalmitis. To identify novel, targetable host inflammatory factors in this disease, we performed microarray analysis to detect TLR4-dependent changes to the retinal transcriptome during B. cereus endophthalmitis.

Results

C57BL/6 J and TLR4^−/− mouse eyes were infected with B. cereus and retinas were harvested at 4 h postinfection, a time representing the earliest onset of neutrophil infiltration. Genes related to acute inflammation and inflammatory cell recruitment including CXCL1 (KC), CXCL2 (MIP2-α), CXCL10 (IP-10), CCL2 (MCP1), and CCL3 (MIP1-α)) were significantly upregulated 5-fold or greater in C57BL/6 J retinas. The immune modulator IL-6, intercellular adhesion molecule ICAM1, and the inhibitor of cytokine signal transduction SOCS3 were upregulated 25-, 11-, and 10-fold, respectively, in these retinas. LIF, which is crucial for photoreceptor cell survival, was increased 6-fold. PTGS2/COX-2, which converts arachidonic acid to prostaglandin endoperoxide H2, was upregulated 9-fold. PTX3, typically produced in response to TLR engagement, was induced 15-fold. None of the aforementioned genes were upregulated in TLR4^−/− retinas following B. cereus infection.

Conclusions

Our results have identified a cohort of mediators driven by TLR4 that may be important in regulating pro-inflammatory and protective pathways in the retina in response to B. cereus intraocular infection. This supports the prospect that blocking the activation of TLR-based pathways might serve as alternative targets for Gram-positive and Gram-negative endophthalmitis therapies in general.

Electronic supplementary material

The online version of this article (10.1186/s12886-018-0764-8) contains supplementary material, which is available to authorized users.

Tanshinone IIA Sodium Sulfonate Attenuates LPS-Induced Intestinal Injury in Mice

Background

Tanshinone IIA sodium sulfonate (TSS) is known to possess anti-inflammatory effects and has exhibited protective effects in various inflammatory conditions; however, its role in lipopolysaccharide- (LPS-) induced intestinal injury is still unknown.

Objective

The present study is designed to explore the role and possible mechanism of TSS in LPS-induced intestinal injury.

Methods

Male C57BL/6J mice, challenged with intraperitoneal LPS injection, were treated with or without TSS 0.5 h prior to LPS exposure. At 1, 6, and 12 h after LPS injection, mice were sacrificed, and the small intestine was excised. The intestinal tissue injury was analyzed by HE staining. Inflammatory factors (TNF-α, IL-1β, and IL-6) in the intestinal tissue were examined by ELISA and RT-PCR. In addition, expressions of autophagy markers (microtubule-associated light chain 3 (LC3) and Beclin-1) were detected by western blot and RT-PCR. A number of autophagosomes were also observed under electron microscopy.

Results

TSS treatment significantly attenuated small intestinal epithelium injury induced by LPS. LPS-induced release of inflammatory mediators, including TNF-α, IL-1β, and IL-6, were markedly inhibited by TSS. Furthermore, TSS treatment could effectively upregulate LPS-induced decrease of autophagy levels, as evidenced by the increased expression of LC3 and Beclin-1, and more autophagosomes.

Conclusion

The protective effect of TSS on LPS-induced small intestinal injury may be attributed to the inhibition of inflammatory factors and promotion of autophagy levels. The present study may provide novel insight into the molecular mechanisms of TSS on the treatment of intestinal injury.

IKKβ Activation in the Fetal Lung Mesenchyme Alters Lung Vascular Development but Not Airway Morphogenesis

In the immature lung, inflammation and injury disrupt the epithelial-mesenchymal interactions required for normal development. Innate immune signaling and NF-κB activation disrupt the normal expression of multiple mesenchymal genes that play a key role in airway branching and alveolar formation. To test the role of the NF-κB pathway specifically in lung mesenchyme, we utilized the mesenchymal Twist2-Cre to drive expression of a constitutively active inhibitor of NF-κB kinase subunit β (IKKβca) mutant in developing mice. Embryonic Twist2-IKKβca mice were generated in expected numbers and appeared grossly normal. Airway branching also appeared normal in Twist2-IKKβca embryos, with airway morphometry, elastin staining, and saccular branching similar to those in control littermates. While Twist2-IKKβca lungs did not contain increased levels of Il1b, we did measure an increased expression of the chemokine-encoding gene Ccl2. Twist2-IKKβca lungs had increased staining for the vascular marker platelet endothelial cell adhesion molecule 1. In addition, type I alveolar epithelial differentiation appeared to be diminished in Twist2-IKKβca lungs. The normal airway branching and lack of Il1b expression may have been due to the inability of the Twist2-IKKβca transgene to induce inflammasome activity. While Twist2-IKKβca lungs had an increased number of macrophages, inflammasome expression remained restricted to macrophages without evidence of spontaneous inflammasome activity. These results emphasize the importance of cellular niche in considering how inflammatory signaling influences fetal lung development.

Src family kinase tyrosine phosphorylates Toll-like receptor 4 to dissociate MyD88 and Mal/Tirap, suppressing LPS-induced inflammatory responses

Src family kinases (SFKs) are a family of protein tyrosine kinases containing nine members: Src, Lyn, Fgr, Hck, Lck, Fyn, Blk, Yes, and Ylk. Although SFK activation is a major immediate signaling event in LPS/Toll-like receptor 4 (TLR4) signaling, its precise role has remained elusive due to various contradictory results obtained from a certain SFK member-deficient mice or cells. The observed inconsistencies may be due to the compensation or redundancy by other SFKs upon a SFK deficiency. The chemical rescuing approach was suggested to induce temporal and precise SFK activation in living cells, thereby limiting the chance of cellular adaption to a SFK-deficient condition. Using the rescuing approach, we demonstrate that restoring SFK activity not only induces tyrosine phosphorylation of TLR4, but also inhibits LPS-induced NFκB and JNK1/2 activation and consequently suppresses LPS-induced cytokine production. TLR4 normally recruits TIR domain-containing adaptors in response to LPS, however, temporally restored SFK activation disrupts the LPS-induced association of MyD88 and Mal/Tirap with TLR4. Additionally, using kinase-dead SFK-Lyn (Y397/508F) and constitutively active SFK-Lyn (Y508F), we found that the kinase-dead SFK inhibits TLR4 tyrosine phosphorylation with reduced binding affinity to TLR4, while the kinase-active SFK strongly binds to TLR4 and promotes TLR4 tyrosine phosphorylation, suggesting that SFK kinase activity is required for TLR4 tyrosine phosphorylation and TLR4-SFK interaction. Together, our results demonstrate that SFK activation induces TLR4 tyrosine phosphorylation, consequently dissociating MyD88 and Mal/Tirap from TLR4 and inhibiting LPS-induced inflammatory responses, suggesting a negative feedback loop regulated by SFK-induced tyrosine phosphorylation in TLR4.

Nociceptin/orphanin FQ antagonizes lipopolysaccharide-stimulated proliferation, migration and inflammatory signaling in human glioblastoma U87 cells

Glioblastoma is among the most aggressive brain tumors and has an exceedingly poor prognosis. Recently, the importance of the tumor microenvironment in glioblastoma cell growth and progression has been emphasized. Toll-like receptor 4 (TLR4) recognizes bacterial lipopolysaccharide (LPS) and endogenous ligands originating from dying cells or the extracellular matrix involved in host defense and in inflammation. G-protein coupled receptors (GPCRs) have gained interest in anti-tumor drug discovery due to the role that they directly or indirectly play by transactivating other receptors, causing cell migration and proliferation. A proteomic analysis showed that the nociceptin receptor (NOPr) is among the GPCRs significantly expressed in glioblastoma cells, including U87 cells. We describe a novel role of the peptide nociceptin (N/OFQ), the endogenous ligand of the NOPr that counteracts cell migration, proliferation and increase in IL-1β mRNA elicited by LPS via TLR4 in U87 glioblastoma cells. Signaling pathways through which N/OFQ inhibits LPS-mediated cell migration and elevation of [Ca2+]i require β-arrestin 2 and are sensitive to TNFR-associated factor 6, c-Src and protein kinase C (PKC). LPS-induced cell proliferation and increase in IL-1β mRNA are counteracted by N/OFQ via β-arrestin 2, PKC and extracellular signal-regulated kinase 1/2; furthermore, the contributions of the transcription factors NF-kB and AP-1 were investigated. Independent of LPS, N/OFQ induces a significant increase in cell apoptosis. Contrary to what was observed in other cell models, a prolonged exposure to this endotoxin did not promote any tolerance of the cellular effects above described, including NOPr down-regulation while N/OFQ loses its inhibitory role.

TLR5 Activation through NF-κB Is a Neuroprotective Mechanism of Postconditioning after Cerebral Ischemia in Mice

Postconditioning has been shown to protect the mouse brain from ischemic injury. However, the neuroprotective mechanisms of postconditioning remain elusive. We have found that toll-like receptor 5 (TLR5) plays an integral role in postconditioning-induced neuroprotection through Akt/nuclear factor kappa B (NF-κB) activation in cerebral ischemia. Compared to animals that received 30 min of transient middle cerebral artery occlusion (tMCAO) group, animals that also underwent postconditioning showed a significant reduction of up to 60.51% in infarct volume. Postconditioning increased phospho-Akt (p-Akt) levels and NF-κB translocation to the nucleus as early as 1 h after tMCAO and oxygen-glucose deprivation. Furthermore, inhibition of Akt by Akt inhibitor IV decreased NF-κB promoter activity after postconditioning. Immunoprecipitation showed that interactions between TLR5, MyD88, and p-Akt were increased from postconditioning both in vivo and in vitro. Similar to postconditioning, flagellin, an agonist of TLR5, increased NF-κB nuclear translocation and Akt phosphorylation. Our results suggest that postconditioning has neuroprotective effects by activating NF-κB and Akt survival pathways via TLR5 after cerebral ischemia. Additionally, the TLR5 agonist flagellin can simulate the neuroprotective mechanism of postconditioning in cerebral ischemia.

Transgenic mice with ectopic expression of constitutively active TLR4 in adipose tissues do not show impaired insulin sensitivity

INTRODUCTION

Chronic low-grade inflammation is associated with obesity and diabetes. However, what causes and mediates chronic inflammation in metabolic disorders is not well understood. Toll-like receptor 4 (TLR4) mediates both infection-induced and sterile inflammation by recognizing pathogen-associated molecular patterns and endogenous molecules, respectively. Saturated fatty acids can activate TLR4, and TLR4-deficient mice were protected from high fat diet (HFD)-induced obesity and insulin resistance, suggesting that TLR4-mediated inflammation may cause metabolic dysfunction, such as obesity and insulin resistance.

METHODS

We generated two transgenic (TG) mouse lines expressing a constitutively active TLR4 in adipose tissue and determined whether these TG mice would show increased insulin resistance.

RESULTS

TG mice fed a high fat or a normal chow diet did not exhibit increased insulin resistance compared to their wild-type controls despite increased localized inflammation in white adipose tissue. Furthermore, females of one TG line fed a normal chow diet had improved insulin sensitivity with reduction in both adiposity and body weight when compared with wild-type littermates. There were significant differences between female and male mice in metabolic biomarkers and mRNA expression in proinflammatory genes and negative regulators of TLR4 signaling, regardless of genotype and diet.

CONCLUSIONS

Together, these results suggest that constitutively active TLR4-induced inflammation in white adipose tissue is not sufficient to induce systemic insulin resistance, and that high fat diet-induced insulin resistance may require other signals in addition to TLR4-mediated inflammation.

Anti-inflammatory action of 2-carbomethoxy-2,3-epoxy-3-prenyl-1,4-naphthoquinone (CMEP-NQ) suppresses both the MyD88-dependent and TRIF-dependent pathways of TLR4 signaling in LPS-stimulated RAW264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

The roots of Rubia cordifolia L. have been widely used as a traditional herbal medicine in Northeast Asia for treating inflammatory diseases.

AIM OF THE STUDY

To elucidate the anti-inflammatory mechanism of 2-carbomethoxy-2,3-epoxy-3- prenyl-1,4-naphthoquinone (CMEP-NQ), purified from the roots of R. cordifolia L. as the major anti-inflammatory component, in LPS-treated RAW264.7 murine macrophage cells.

MATERIALS AND METHODS

Anti-inflammatory activity of CMEP-NQ was investigated in LPS-treated RAW264.7 cells by measuring the levels of NO, PGE₂, and cytokines (IL1β, IL-6, TNF-α) in the culture supernatants and the TLR4-mediated intracellular events including association of MyD88 with IRAK1, activation of IRAK1, TAK1, MAPKs, NF-κB/AP-1, and IRF3, and generation of ROS.

RESULTS

Pretreatment of RAW264.7 cells with CMEP-NQ reduced LPS-induced production of NO and PGE₂ by suppressing iNOS and COX-2 gene expression. CMEP-NQ also reduced the secretion of IL-1β, IL-6, and TNF-α by down-regulating mRNA levels. Under these conditions, TLR4-mediated MyD88-dependent events were inhibited by CMEP-NQ, including the association of MyD88 with IRAK1, phosphorylation of IRAK1, TAK1, and MAPKs (ERK, JNK and p38 MAPK), and activation of NF-κB and AP-1. As TRIF-dependent events of TLR4 signaling, phosphorylation of IRF3 and induction of iNOS protein expression were also inhibited by CMEP-NQ. However, the binding of FITC-conjugated LPS to cell surface TLR4 was not affected by CMEP-NQ. Following LPS stimulation, intracellular ROS production was first detected by DCFH-DA staining at 1h; then it continuously increased until 16h. Although CMEP-NQ failed to exhibit DPPH radical- or ABTS radical-scavenging activity in vitro, LPS-induced ROS production in RAW264.7 cells was more efficiently blocked by CMEP-NQ than by NAC.

CONCLUSIONS

These results demonstrate that the suppressive effect of CMEP-NQ on LPS-induced inflammatory responses in RAW264.7 cells was mainly exerted via its inhibition of TLR4-mediated proximal events, such as MyD88-dependent NF-κB/AP-1 activation and ROS production, and TRIF-dependent IRF3 activation.

Cereus sinensis Polysaccharide and Its Immunomodulatory Properties in Human Monocytic Cells

In this study, the extraction conditions of the crude polysaccharide from Cereus sinensis were optimized by response surface methodology. The optimum extraction conditions were: a ratio of raw material to water volume of 1:80 (g/mL); an extraction temperature of 72 °C; and an extraction time of 3 h. Then, a purified polysaccharide named Cereus sinensis polysaccharide-1 (CSP-1) was obtained from the crude polysaccharide by the Diethylaminoethyl cellulose-52 (DEAE-52) cellulose chromatography column and Sephadex G-100 column. The molecular weight and monosaccharide composition of CSP-1 was determined through Gel Permeation Chromatography (GPC) and Gas Chromatography–Mass Spectrometer (GS–MS), respectively. The results showed that CSP-1 with an average molecular weight of 56,335 Da was composed of l-(−)-Fucose, d-(+)-Mannose, d-Glucose and mainly possessed 1→2, 1→2, 6, 1→4, and 1→4, 6 of glycosyl linkages. The immunomodulatory activities of CSP-1 were also evaluated using lipopolysaccharide (LPS)-induced human monocytic (THP-1) cells. The results demonstrated that CSP-1 dose-dependently protected against LPS-induced toxicity, and CSP-1 significantly inhibited the Toll-like receptor 4 (TLR-4) mRNA, myeloid differentiation factor 88 (MyD88) mRNA and tumour necrosis factor receptor-associated factor-6 (TRAF-6) mRNA expression of the LPS-induced THP-1 cells, as well as suppressing reactive oxygen species (ROS) generation.

Oxidized phospholipids exert a dual effect on bile acid-induced CCL2 expression in pancreatic acini

BACKGROUND

oxidized phospholipids (oxPLs) generated in inflammatory diseases could play a key role by inducing pro- and anti-inflammatory effects. OBJETIVES: we investigated the effect of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and oxidized POPC (oxPOPC) in the inflammatory response triggered in pancreatic acini.

METHODS

control acini were incubated in the absence or presence of either POPC or oxPOPC (≤100 μM). In additional experiments, oxPOPC effects were evaluated in sodium taurocholate (NaTc)-treated acini. CCL2 and TLR4 mRNA expression was analyzed by RT-qPCR. By western blot, JNK-MAPK, JAK and IκBα in cytoplasm as well as p65-NF-kB and p-STAT3 in the nucleus were evaluated. The involvement of TLR4, JNK-MAPK, JAK as well as NF-kB, STAT3 and PPARγ was assessed using pharmacological inhibition.

RESULTS

no effect was found in response to POPC. Conversely, in response to oxPOPC (10 μM), JNK-MAPK and JAK acted as TLR4-downstream signals, leading to CCL2 upregulation mainly through NF-kB activation. Moreover, TLR4 non-dependent mechanisms induced STAT3 activation in oxPOPC-treated acini. Mediated by PPARγ, oxPOPC (50 μM) inhibited the CCL2 overexpression found in NaTc-treated acini.

CONCLUSIONS

oxPOPC exerts pro- and anti-inflammatory effects in pancreatic acinar cells mediated by TLR4 and PPARγ signals, respectively. This dual action proved to be dependent on the concentration. The molecular mechanisms involved in the oxPL response could be useful for new therapeutic approaches to the treatment of oxPLs-related inflammatory pathologies.

Roles of 5-lipoxygenase and cyclooxygenase-2 in the biosynthesis of hemiketals E2 and D2 by activated human leukocytes

The 2 hemiketal (HK) eicosanoids HKD₂ and HKE₂ are the major products of the biosynthetic crossover of the 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) pathways. HKs result from the rearrangement of a di-endoperoxide intermediate formed in the COX-2-dependent oxygenation of 5S-hydroxyeicosatetraenoic acid (5S-HETE). We analyzed HK biosynthesis in human leukocytes stimulated ex vivo and defined the biosynthetic roles of 5-LOX and COX-2, using inhibitors and incubations with exogenous substrates. Activation of leukocytes with LPS followed by treatment with the calcium ionophore A23187 resulted in the formation of PGE₂, 5-HETE, and LTB₄ as the principal metabolites of COX-2 and 5-LOX, respectively. The formation of HKD₂ and HKE₂ was highest after 15 min LPS treatment, and at that time, levels were similar to PGE₂, but less than 5-HETE and LTB₄ The time course of HK formation paralleled that of 5-HETE and LTB₄, implying the availability of the 5S-HETE substrate as a limiting factor in biosynthesis rather than expression levels of COX-2. Specific inhibitors of COX-2 and 5-LOX decreased formation of HKD₂ and HKE₂ Platelets did not form HKs from exogenous 5S-HETE, implying that COX-1 is not involved. HKs are early products during an inflammatory event and require cells that express 5-LOX and COX-2 for their biosynthesis.-Giménez-Bastida, J. A., Shibata, T., Uchida, K., Schneider, C. Roles of 5-lipoxygenase and cyclooxygenase-2 in the biosynthesis of hemiketals E₂ and D₂ by activated human leukocytes.

Deer Bone Oil Extract Suppresses Lipopolysaccharide-Induced Inflammatory Responses in RAW264.7 Cells

The aim of this study was to investigate the effect of deer bone oil extract (DBOE) on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 cells. DBOE was fractionated by liquid-liquid extraction to obtain two fractions: methanol fraction (DBO-M) and hexane fraction (DBO-H). TLC showed that DBO-M had relatively more hydrophilic lipid complexes, including unsaturated fatty acids, than DBOE and DBO-H. The relative compositions of tetradecenoyl carnitine, α-linoleic acid, and palmitoleic acid increased in the DBO-M fraction by 61, 38, and 32%, respectively, compared with DBOE. The concentration of sugar moieties was 3-fold higher in the DBO-M fraction than DBOE and DBO-H. DBO-M significantly decreased LPS-induced nitric oxide (NO) production in RAW264.7 cells in a dose-dependent manner. This DBO-M-mediated decrease in NO production was due to downregulation of mRNA and protein levels of inducible nitric oxide synthase (iNOS). In addition, mRNA expression of pro-inflammatory mediators, such as cyclooxygenase (COX-2), interleukin (IL)-1β, and IL-12β, was suppressed by DBO-M. Our data showed that DBO-M, which has relatively higher sugar content than DBOE and DBO-H, could play an important role in suppressing inflammatory responses by controlling pro-inflammatory cytokines and mediators.

Paying for the Tolls: The High Cost of the Innate Immune System for the Cardiac Myocyte

The cardiac myocyte differs strikingly from the specialized cells of the immune system, which has two different responses to invading organisms and tissue damage. Adaptive or acquired immunity generates highly specific antibodies in response to threats and is an essential component of immunity; however, adaptive immunity can take 4-7 days to mobilize, and a more primitive response, innate immunity, fills the gap. Innate immunity is expressed in complex and in primitive life forms. Specialized receptors, Toll-like receptors (TLRs), which are widely distributed throughout different tissues recognize danger signals and rapidly respond with the release of noxious substances, such as TNFα. The problem is that many endogenous molecules have been found to act as ligands for specific TLRs, and when these molecules are released into the extracellular environment, they can cause problems by activating innate immunity and an inflammatory response. In cardiac myocytes heat shock protein (HSP)60 can activate TLR4, as can HMGB1, and this type of response can amplify the response to ischemia/reperfusion leading to increased cell and tissue injury. Activation of TLRs can potentially amplify chronic, inflammatory diseases, such as ischemic heart failure. Thus, it is important to understand the regulation of the TLRs and their downstream effects. This chapter will focus on the TLRs and cardiac myocytes.

N,N-Dimethylacetamide Significantly Attenuates LPS- and TNFα-Induced Proinflammatory Responses Via Inhibition of the Nuclear Factor Kappa B Pathway

Previously, we have shown that N,N-dimethylacetamide (DMA) prevents inflammation-induced preterm birth in a murine model, inhibits LPS-induced increases in placental pro-inflammatory cytokines and up-regulates the anti-inflammatory cytokine Interleukin-10 (IL-10). However, DMA's mechanism of action remains to be elucidated. In the current study we investigate how DMA produces its anti-inflammatory effect. Using in vitro and ex vivo models, we show that DMA suppresses secretion of pro-inflammatory cytokines in lipopolysaccharide (LPS)-induced RAW 264.7 cells, TNFα-challenged JEG-3 cells and LPS-stimulated human placental explants. DMA significantly attenuated the secretion of TNFα, IL-6, IL-10, and granulocyte macrophage colony stimulating factor (GM-CSF) from LPS-stimulated RAW 264.7 cells, IL-6 secretion from TNFα-stimulated JEG-3 cells and TNFα, IL-6, IL-10, GM-CSF and Interleukin-8 (IL-8) from LPS-stimulated human placental explants. We further investigated if DMA's effect on cytokine expression involves the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. DMA (10 mM) significantly inhibited nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) degradation in LPS-stimulated RAW 264.7 cells, but there was no significant change in the expression of phosphorylated or native forms of downstream proteins in the MAPK pathway. In addition, DMA significantly attenuated luciferase activity in cells co-transfected with NF-κB-Luc reporter plasmid, but not with AP-1-Luc or CEBP-Luc reporters. Overall, our findings suggest that the anti-inflammatory activity of DMA is mediated by inhibition of the NF-κB pathway via decreased IκBα degradation.

TLR2- and TLR4-dependent activation of STAT1 serine phosphorylation in murine macrophages is protein kinase C-δ-independent

Engagement of Toll-like receptor (TLR) proteins activates multiple signal transduction pathways. Previous studies demonstrated that TLR2 and TLR4 engagement leads to rapid phosphorylation of the transcription factor STAT1 at serine 727 (Ser-727 STAT1) in murine macrophages. Only TLR4 engagement induced STAT1 phosphorylation at tyrosine 701, although this response was delayed compared with Ser-727 STAT1 phosphorylation. Unlike other cell types, the p38 mitogen-activated protein kinase was necessary, but not sufficient, for TLR-induced phosphorylation of Ser-727 STAT1 in macrophages. We and others had previously shown that Ser-727 STAT1 phosphorylation could be blocked by rottlerin, an inhibitor of protein kinase C-δ (PKC—δ). Here we report that peritoneal exudate macrophages from PKC-δ-deficient mice can be activated through TLR2 and TLR4 to elicit rapid phosphorylation of Ser-727 STAT1, which was blocked by both rottlerin and the p38 inhibitor SB203580, but not by the pan-PKC inhibitor bisindoylmaleamide. Furthermore, both normal and PKC-δ-deficient macrophages secreted comparable amounts of IL-6, IP-10, and RANTES following TLR engagement. In contrast, IFN-γ-induced STAT1 serine phosphorylation was independent of both PKC-δ and p38. Overall, these studies demonstrate that a PKC-δindependent signaling pathway downstream of both TLR2 and TLR4 is necessary for Ser-727 STAT1 phosphorylation in primary murine macrophages.

Lipopolysaccharide treatment induces genome-wide pre-mRNA splicing pattern changes in mouse bone marrow stromal stem cells

BACKGROUND

Lipopolysaccharide (LPS) is a gram-negative bacterial antigen that triggers a series of cellular responses. LPS pre-conditioning was previously shown to improve the therapeutic efficacy of bone marrow stromal cells/bone-marrow derived mesenchymal stem cells (BMSCs) for repairing ischemic, injured tissue.

RESULTS

In this study, we systematically evaluated the effects of LPS treatment on genome-wide splicing pattern changes in mouse BMSCs by comparing transcriptome sequencing data from control vs. LPS-treated samples, revealing 197 exons whose BMSC splicing patterns were altered by LPS. Functional analysis of these alternatively spliced genes demonstrated significant enrichment of phosphoproteins, zinc finger proteins, and proteins undergoing acetylation. Additional bioinformatics analysis strongly suggest that LPS-induced alternatively spliced exons could have major effects on protein functions by disrupting key protein functional domains, protein-protein interactions, and post-translational modifications.

CONCLUSION

Although it is still to be determined whether such proteome modifications improve BMSC therapeutic efficacy, our comprehensive splicing characterizations provide greater understanding of the intracellular mechanisms that underlie the therapeutic potential of BMSCs.

In vitro comparison of the effects of probiotic, commensal and pathogenic strains on macrophage polarization

Macrophages are important with respect to both innate and adaptive immune responses and are known to differentiate into pro-inflammatory M1- or anti-inflammatory M2-phenotypes following activation. In order to study how different bacteria affect macrophage polarization, we exposed murine RAW 264.7 macrophages to sixteen different strains representing probiotic strains, pathogens, commensals and strains of food origin. Increased inducible nitric oxide synthase (iNOS) or arginase-1 gene expression indicates M1 or M2 polarization, respectively, and was quantified by qRT-PCR. Strains of Escherichia and Salmonella elevated iNOS expression more so than strains of Enterococcus, Lactobacillus and Lactococcus, indicating that Gram-negative strains are more potent M1 inducers. However, strain-specific responses were observed. For instance, Escherichia coli Nissle 1917 was a poor inducer of iNOS gene expression compared to the other E. coli strains, while Enterococcus faecalis Symbioflor-1 was more potent in this respect compared to all the eleven Gram-positive strains tested. Macrophage polarization was further characterized by quantifying secreted pro- and anti-inflammatory cytokines. Exposure to the pathogen E. coli 042 produced a cytokine profile indicating M1 differentiation, which is in accordance with the PCR data. However, exposure to most strains resulted in either high or low secretion levels of all cytokines tested, rather than a clear M1 or M2 profile. In general, the Gram-negative strains induced high levels of cytokine secretion compared to the Gram-positive strains. Interestingly, strains of human origin had a higher impact on macrophages compared to strains of food origin.

Alveolar Epithelial Cell-Derived Prostaglandin E2 Serves as a Request Signal for Macrophage Secretion of Suppressor of Cytokine Signaling 3 during Innate Inflammation

Preservation of gas exchange mandates that the pulmonary alveolar surface restrain unnecessarily harmful inflammatory responses to the many challenges to which it is exposed. These responses reflect the cross-talk between alveolar epithelial cells (AECs) and resident alveolar macrophages (AMs). We recently determined that AMs can secrete suppressor of cytokine signaling (SOCS) proteins within microparticles. Uptake of these SOCS-containing vesicles by epithelial cells inhibits cytokine-induced STAT activation. However, the ability of epithelial cells to direct AM release of SOCS-containing vesicles in response to inflammatory insults has not been studied. In this study, we report that SOCS3 protein was elevated in bronchoalveolar lavage fluid of both virus- and bacteria-infected mice, as well as in an in vivo LPS model of acute inflammation. In vitro studies revealed that AEC-conditioned medium (AEC-CM) enhanced AM SOCS3 secretion above basal levels. Increased amounts of PGE2 were present in AEC-CM after LPS challenge, and both pharmacologic inhibition of PGE2 synthesis in AECs and neutralization of PGE2 in AEC-CM implicated this prostanoid as the major AEC-derived factor mediating enhanced AM SOCS3 secretion. Moreover, pharmacologic blockade of PGE2 synthesis or genetic deletion of a PGE2 synthase similarly attenuated the increase in bronchoalveolar lavage fluid SOCS3 noted in lungs of mice challenged with LPS in vivo. These results demonstrate a novel tunable form of cross-talk in which AECs use PGE2 as a signal to request SOCS3 from AMs to dampen their endogenous inflammatory responses during infection.

Repeated LPS Injection Induces Distinct Changes in the Kynurenine Pathway in Mice

The immune system has been recognized as a potential contributor to psychiatric disorders. In animals, lipopolysaccharide (LPS) is used to induce inflammation and behaviors analogous to some of the symptoms in these disorders. Recent data indicate that the kynurenine pathway contributes to LPS-induced aberrant behaviors. However, data are inconclusive regarding optimal LPS dose and treatment strategy. Here, we therefore aimed to evaluate the effects of single versus repeated administration of LPS on the kynurenine pathway. Adult C57BL6 mice were given 0.83 mg/kg LPS as a single or a repeated injection (LPS + LPS) and sacrificed after 24, 48, 72, or 120 h. Mice receiving LPS + LPS had significantly elevated brain kynurenine levels at 24 and 48 h, and elevated serum kynurenine at 24, 48 and 72 h. Brain kynurenic acid and quinolinic acid were significantly increased at 24 and 48 h in mice receiving LPS + LPS, whereas serum kynurenic acid levels were significantly decreased at 24 h. The increase of brain kynurenic acid by LPS + LPS was likely unrelated to the higher total dose as a separate group of mice receiving 1.66 mg/kg LPS as single injection 24 h prior to sacrifice did not show increased brain kynurenic acid. Serum quinolinic acid levels were not affected by LPS + LPS compared to vehicle. Animals given repeated injections of LPS showed a more robust induction of the kynurenine pathway in contrast to animals receiving a single injection. These results may be valuable in light of data showing the importance of the kynurenine pathway in psychiatric disorders.

Mechanisms for the activation of Toll-like receptor 2/4 by saturated fatty acids and inhibition by docosahexaenoic acid

Saturated fatty acids can activate Toll-like receptor 2 (TLR2) and TLR4 but polyunsaturated fatty acids, particularly docosahexaenoic acid (DHA) inhibit the activation. Lipopolysaccharides (LPS) and lipopetides, ligands for TLR4 and TLR2, respectively, are acylated by saturated fatty acids. Removal of these fatty acids results in loss of their ligand activity suggesting that the saturated fatty acyl moieties are required for the receptor activation. X-ray crystallographic studies revealed that these saturated fatty acyl groups of the ligands directly occupy hydrophobic lipid binding domains of the receptors (or co-receptor) and induce the dimerization which is prerequisite for the receptor activation. Saturated fatty acids also induce the dimerization and translocation of TLR4 and TLR2 into lipid rafts in plasma membrane and this process is inhibited by DHA. Whether saturated fatty acids induce the dimerization of the receptors by interacting with these lipid binding domains is not known. Many experimental results suggest that saturated fatty acids promote the formation of lipid rafts and recruitment of TLRs into lipid rafts leading to ligand independent dimerization of the receptors. Such a mode of ligand independent receptor activation defies the conventional concept of ligand induced receptor activation; however, this may enable diverse non-microbial molecules with endogenous and dietary origins to modulate TLR-mediated immune responses. Emerging experimental evidence reveals that TLRs play a key role in bridging diet-induced endocrine and metabolic changes to immune responses.

Antioxidant and Anti-Inflammatory Effects of Chaenomeles sinensis Leaf Extracts on LPS-Stimulated RAW 264.7 Cells

The fruit of Chaenomeles sinensis has been traditionally used in ethnomedicine for the treatment of various human ailments, including pneumonia, bronchitis, and so on, but the pharmacological applications of the leaf part of the plant have not been studied. In this study, we evaluated the various radical scavenging activities and anti-inflammatory effects of different Chaenomeles sinensis leaf (CSL) extracts. The water extract showed a higher antioxidant and radical scavenging activities. However the ethanolic extracts showed higher NO scavenging activity than water extract, therefore the ethanolic extract of CSL was examined for anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The 70% ethanol extract of CSL (CSLE) has higher anti-inflammatory activity and significantly inhibited the production of nitric oxide (NO), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). In addition, CSLE suppressed LPS-stimulated inducible nitric oxide synthase (iNOS) and NO production, IL-1β and phospho-STAT1 expression. In this study, we investigated the effect of CSLE on the production of inflammatory mediators through the inhibition of the TRIF-dependent pathways. Furthermore, we evaluated the role of CSLE on LPS-induced expression of pro-inflammatory cytokines, such as TNF-α, IL-1β and IL-6. Our results suggest that CSLE attenuates the LPS-stimulated inflammatory responses in macrophages through regulating the key inflammatory mechanisms, providing scientific support for its traditional uses in treating various inflammatory diseases.

Myeloid differentiation primary response gene 88-leukotriene B4 receptor 2 cascade mediates lipopolysaccharide-potentiated invasiveness of breast cancer cells

Inflammation and local inflammatory mediators are inextricably linked to tumor progression through complex pathways in the tumor microenvironment. Lipopolysaccharide (LPS) exposure to tumor cells has been suggested to promote tumor invasiveness and metastasis. However, the detailed signaling mechanism involved has not been elucidated. In this study, we showed that LPS upregulated the expression of leukotriene B₄ receptor-2 (BLT2) and the synthesis of BLT2 ligands in MDA-MB-231 and MDA-MB-435 breast cancer cells, thereby promoting invasiveness. BLT2 depletion with siRNA clearly attenuated LPS-induced invasiveness. In addition, we demonstrated that myeloid differentiation primary response gene 88 (MyD88) lies upstream of BLT2 in LPS-potentiated invasiveness and that this ‘MyD88-BLT2’ cascade mediates activation of NF-κB and the synthesis of IL-6 and IL-8, which are critical for the invasiveness and aggression of breast cancer cells. LPS-driven metastasis of MDA-MB-231 cells was also markedly suppressed by the inhibition of BLT2. Together, our results demonstrate, for the first time, that LPS potentiates the invasiveness and metastasis of breast cancer cells via a ‘MyD88-BLT2’-linked signaling cascade.

PAMAM dendrimers as nano carriers to investigate inflammatory responses induced by pulmonary exposure of PCB metabolites in Sprague-Dawley rats

Polychlorinated biphenyls (PCBs) persist and accumulate in the ecosystem depending upon the degree of chlorination of the biphenyl rings. Airborne PCBs are especially susceptible to oxidative metabolism, yielding mono- and di-hydroxy metabolites. We have previously demonstrated that 4-chlorobiphenyl hydroquinones (4-CB-HQs) acted as cosubstrates for arachidonic acid metabolism by prostaglandin H synthase (PGHS) and resulted in an increase of prostaglandin production in vitro. In the present study, we tested the capability of 4-CB-HQ to act as a co-substrate for PGHS catalysis in vivo. BQ and 4-CB-2',5'-HQ were administered intratracheally to male Sprague-Dawley rats (2.5 μmol/kg body weight) using nanosized polyamidoamine (PAMAM) dendrimers as carriers. We found that 24 h post application, PGE2 metabolites in kidney of rats treated with 4-CB-2',5'-HQ were significantly increased compared to the controls. The increase of PGE2 metabolites was correlated with increased alveolar macrophages in lung lavage fluid. The elevation of PGE2 synthesis is of great interest since it plays a crucial role in balancing homeostasis and inflammation where a chronic disturbance may increase risk of cancer. PAMAM dentrimers proved to be an effective transport medium and did not stimulate an inflammatory response themselves.

c-Jun N-terminal kinase-mediated anti-inflammatory effects of Garcinia subelliptica in macrophages

Garcinia plants have been traditionally used to treat inflammatory diseases, such as skin infections and pain, in many regions including South‑East Asia. Garcinia subelliptica, a plant of the Garcinia species widely distributed from Japan to Thailand, has been reported to contain components similar to other Garcinia plants that exhibit anti‑inflammatory effects. The present study aimed to explore the anti‑inflammatory effects of ethanol extracts of Garcinia subelliptica (EGS) in macrophages, as there are no previous systemic studies that have investigated the effects of Garcinia subelliptica on inflammation. Non‑cytotoxic concentrations of EGS (≤200 µg/ml) were observed to reduce nitric oxide production by modulating iNOS expression in lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. The expression of cyclooxygenase‑2, the enzyme responsible for the production of prostaglandin E2, was notably reduced by EGS. EGS treatment inhibited the production of pro‑inflammatory cytokines, including IL‑6 and IL‑1β, however, not TNF‑α. Reduced production of inflammatory mediators by EGS was followed by reduced phosphorylation of c‑Jun N‑terminal kinase (JNK) however, not of other mitogen‑activated protein kinases and nuclear factor‑κB. These results indicate that EGS selectively inhibits the excessive production of inflammatory mediators in LPS‑stimulated murine macrophages by reducing the activation of JNK, suggesting that EGS is a candidate for modulating severe inflammation.

Gedunin Binds to Myeloid Differentiation Protein 2 and Impairs Lipopolysaccharide-Induced Toll-Like Receptor 4 Signaling in Macrophages

Recognition of bacterial lipopolysaccharide (LPS) by innate immune system is mediated by the cluster of differentiation 14/Toll-like receptor 4/myeloid differentiation protein 2 (MD-2) complex. In this study, we investigated the modulatory effect of gedunin, a limonoid from species of the Meliaceae family described as a heat shock protein Hsp90 inhibitor, on LPS-induced response in immortalized murine macrophages. The pretreatment of wild-type (WT) macrophages with gedunin (0.01-100 µM, noncytotoxic concentrations) inhibited LPS (50 ng/ml)-induced calcium influx, tumor necrosis factor-α, and nitric oxide production in a concentration-dependent manner. The selective effect of gedunin on MyD88-adapter-like/myeloid differentiation primary response 88- and TRIF-related adaptor molecule/TIR domain-containing adapter-inducing interferon-β-dependent signaling pathways was further investigated. The pretreatment of WT, TIR domain-containing adapter-inducing interferon-β knockout, and MyD88 adapter-like knockout macrophages with gedunin (10 µM) significantly inhibited LPS (50 ng/ml)-induced tumor necrosis factor-α and interleukin-6 production, at 6 hours and 24 hours, suggesting that gedunin modulates a common event between both signaling pathways. Furthermore, gedunin (10 µM) inhibited LPS-induced prostaglandin E2 production, cyclooxygenase-2 expression, and nuclear factor κB translocation into the nucleus of WT macrophages, demonstrating a wide-range effect of this chemical compound. In addition to the ability to inhibit LPS-induced proinflammatory mediators, gedunin also triggered anti-inflammatory factors interleukin-10, heme oxygenase-1, and Hsp70 in macrophages stimulated or not with LPS. In silico modeling studies revealed that gedunin efficiently docked into the MD-2 LPS binding site, a phenomenon further confirmed by surface plasmon resonance. Our results reveal that, in addition to Hsp90 modulation, gedunin acts as a competitive inhibitor of LPS, blocking the formation of the Toll-like receptor 4/MD-2/LPS complex.

Corticotropin Releasing Hormone and Urocortin 3 Stimulate Vascular Endothelial Growth Factor Expression through the cAMP/CREB Pathway

Colonic epithelium is the first line of defense against various pathological offenses in the gut. Previous studies have shown that the peptides of the corticotropin-releasing hormone (CRH) family modulate vascular endothelial growth factor (VEGF)-A production in other cells. Here we sought to investigate whether CRH and urocortin (Ucn) 3 regulate VEGF-A secretion in colonocytes through CRH receptors and to elucidate the underlying mechanism of action. CRH and Ucn 3 significantly increased the expression levels of VEGF-A mRNA and protein through CRH receptor 1 and 2, respectively, in human colonic epithelial cells and primary mouse intestinal epithelial cells. Underlying mechanisms involve activation of adenylyl cyclase with subsequent increase of intracellular cAMP level and increased DNA binding activity of transcription factor CREB on VEGF-A promoter region. Finally, genetic deficiency of CREB decreased intestinal inflammation and VEGF-A expression in a dextran sodium sulfate-induced colitis model. These results show that activation of CRH receptors by CRH ligands stimulates VEGF-A expression in intestinal epithelial cells through the cAMP/CREB pathway. Since VEGF-A boosts inflammatory responses through angiogenesis, these data suggest that CREB may be a key effector of CRH and Ucn 3-dependent inflammatory angiogenesis.

On the antioxidant, neuroprotective and anti-inflammatory properties of S-allyl cysteine: An update

Therapeutic approaches based on isolated compounds obtained from natural products to handle central and peripheral disorders involving oxidative stress and inflammation are more common nowadays. The validation of nutraceutics vs. pharmaceutics as tools to induce preventive and protective profiles in human health alterations is still far of complete acceptance, but the basis to start more solid experimental and clinical protocols with natural products has already begun. S-allyl cysteine (SAC) is a promising garlic-derived organosulfur compound exhibiting a considerable number of positive actions in cell models and living systems. An update, in the form of review, is needed from time to time to get access to the state-of-the-art on this topic. In this review we visited recent and refreshing evidence of new already proven and potential targets to explain the benefits of using SAC against toxic and pathological conditions. The broad spectrum of protective actions covered by this molecule comprises antioxidant, redox modulatory and anti-inflammatory activities, accompanied by anti-apoptotic, pro-energetic and signaling capacities. Herein, we detail the evidence on these aspects to provide the reader a more complete overview on the promising aspects of SAC in research.

Aberrant expression of shared master-key genes contributes to the immunopathogenesis in patients with juvenile spondyloarthritis

Association of juvenile spondyloarthritis (jSpA) with the HLA-B27 genotype is well established, but there is little knowledge of other genetic factors with a role in the development of the disease. To date, only a few studies have tried to find those associated genes by obtaining expression profiles, but with inconsistent results due to various patient selection criteria and methodology. The aim of the present study was to identify and confirm gene signatures and novel biomarkers in highly homogeneous cohorts of untreated and treated patients diagnosed with jSpA and other forms of juvenile idiopathic arthritis (JIA) according to ILAR criteria. For the purposes of the research, total RNA was isolated from whole blood of 45 children with jSpA and known HLA genotype, 11 children with oligo- and polyarticular forms of JIA, as well as 12 age and sex matched control participants without diagnosis of inflammatory disease. DNA microarray gene expression was performed in 11 patients with jSpA and in four healthy controls, along with bioinformatical analysis of retrieved data. Carefully selected differentially expressed genes where analyzed by qRT-PCR in all participants of the study. Microarray results and bioinformatical analysis revealed 745 differentially expressed genes involved in various inflammatory processes, while qRT-PCR analysis of selected genes confirmed data universality and specificity of expression profiles in jSpA patients. The present study indicates that jSpA could be a polygenic disease with a possible malfunction in antigen recognition and activation of immunological response, migration of inflammatory cells and regulation of the immune system. Among genes involved in these processes TLR4, NLRP3, CXCR4 and PTPN12 showed almost consistent expression in study patients diagnosed with jSpA. Those genes and their products could therefore potentially be used as novel biomarkers, possibly predictive of disease prognosis and response to therapy, or even as a target for new therapeutic approaches.

Liver kinase B1 suppresses lipopolysaccharide-induced nuclear factor κB (NF-κB) activation in macrophages

Liver kinase B1 (LKB1), a serine/threonine kinase, is a tumor suppressor and metabolic regulator. Recent data suggest that LKB1 is essential in regulating homeostasis of hematopoietic cells and immune responses. However, its role in macrophages and innate immune system remains unclear. Here we report that macrophage LKB1 inhibits pro-inflammatory signaling in response to LPS. LPS-induced pro-inflammatory cytokines and pro-inflammatory enzymes were monitored in bone marrow-derived macrophages isolated from myeloid cell-specific LKB1 knock out mice and their wild type littermate control mice. LPS induced higher levels of pro-inflammatory cytokines and pro-inflammatory enzymes in bone marrow-derived macrophages from LKB1 KO than those from wild type mice. Consistently, LPS induced higher levels of NF-κB activation in LKB1-deficient macrophages than those in wild type. Further, LPS stimulation significantly increased LKB1 phosphorylation at serine 428, which promoted its binding to IκB kinaseβ (IKKβ), resulting in the inhibition of NF-κB. Finally, LPS injection caused higher levels of cytokine release and more severe tissue injury in the lung tissues of LKB1 KO mice than in those of control mice. We conclude that LKB1 inhibits LPS-induced NF-κB activation in macrophages.

Over-expression of TLR4-CD14, pro-inflammatory cytokines, metabolic markers and NEFAs in obese non-diabetic Mexicans

Introduction

Obesity is the world’s most important public health problem. Adipose tissue contributes significantly to increase pro-inflammatory mediators whose cascade begins with the union of TLR4 to its microbial ligands (TLR: Toll Like Receptors). It has been reported recently that NEFAs (Non-Esterified Fatty Acids) bind to this receptor as agonists. The purpose of our study was to determine the levels of expression of TLR4-CD14, the pro-inflammatory cytokines, the metabolic markers and the NEFAs in a group of adult, non-diabetic obese Mexicans.

Method

A group of 210 adult middle-class Mexican non-diabetic obese patients was evaluated: 105 normal weight individuals, and 105 non-diabetic obese. On both groups, the following was tested in each patient: TLR4-CD14 receptors on monocytes in peripheral blood, inflammatory profile, HOMA-IR (Homeostasis Model Assessment-Insulin Resistance), NEFAs and each individual’s anthropometric profile.

Results

Obesity is strongly associated with the expression of TLR4 (77%, MFI (Mean Fluorescence Index) 7.70) and CD14 (86% MFI 1.61) with 66% double positives (p = 0.000). These figures contrast with those for the normal weight individuals that constituted the control group: TLR4 (70% MFI 6.41) and CD14 (84% MFI 1.25) with 59% double positives. As for cytokine concentration, non- diabetic obese individuals vs the normal weight/thin, the numbers were: IL-1β = 2.0 vs 2.5 pg/ml (p = NS), IL-6 = 36 vs 28 pg/ml (p = 0.030), IL-8 = 27 vs 27 pg/ml (p = NS), IL-10 = 8.4 vs 6.8 pg/ml (p = NS), TNF-α =31 vs 15 pg/ml (p = 0.000) respectively. Insulin levels were 12.1 vs 19.7 mcU/ml (p = 0.000) and the NEFAs were much higher in the obese vs normal weight/thin individuals (p = 0.000).

Conclusion

Adipose tissue used to be thought of as mere storage of fats and energy, but it has been revealed to be an important neuro-immune-endocrine organ. Immune cells, stimulated by NEFAs, produce pro-inflammatory cytokines, which have a direct effect on oxidating radicals that directly target the release of noradrenalin. This in turn, reactivates the vicious cycle of low-grade chronic inflammation, as is now described in obesity.

Disruption of Pten speeds onset and increases severity of spontaneous colitis in Il10(-/-) mice

BACKGROUND & AIMS

Early-onset ulcerative colitis, which is considered severe colonic inflammation that develops in infants and young children, can be caused by alterations in interleukin (IL)-10 signaling, although other factors are involved in its pathogenesis. We investigated whether loss of phosphatase and tensin homologue (PTEN), which regulates many important cell functions such as cell proliferation, cell survival, and Toll-like receptor (TLR) signaling pathways, contributes to the development of colitis in Il10(-/-) mice.

METHODS

We generated Il10(-/-) mice (in C57BL/6 and C3H/HeJBir background strains) with disruption of Pten in the intestinal epithelium (Ints(ΔPten/ΔPten);Il10(-/-) mice) and Ints(ΔCont);Il10(-/-) (control) mice. Colon tissues were collected and histological, transmission electron microscopy, and gene expression analysis were performed. Fecal microbiota samples were analyzed by sequencing of 16S ribosomal RNA genes. We disrupted Tlr4 in Ints(ΔPten/ΔPten);Il10(-/-) mice. Lipopolysaccharide signaling via TLR4 was blocked by treating mice with polymyxin B.

RESULTS

Il10(-/-) mice developed colitis when they were 6 to 7 months old, whereas Ints(ΔPten/ΔPten);Il10(-/-) mice developed severe colitis and colon tumors by the time they were 36 days old. Within 3 months of birth, 80% of Ints(ΔPten/ΔPten);Il10(-/-) mice developed severe colitis and colonic malignancy, whereas none of the Ints(ΔCont);Il10(-/-) mice had these phenotypes. Ints(ΔPten/ΔPten);Il10(-/-) mice had alterations in fecal microbiota compared with controls, such as increased proportions of Bacteroides species, which are gram negative. Disruption of Tlr4 or treating Ints(ΔPten/ΔPten);Il10(-/-) mice with polymyxin B delayed the development of colitis and reduced disease severity.

CONCLUSIONS

Disruption of Pten in the intestinal epithelium of Il10(-/-) mice speeds the onset and increases the severity of colitis. Fecal microbiota from Ints(ΔPten/ΔPten);Il10(-/-) mice have increased proportions of Bacteroides species. Development of colitis is delayed and reduced by blocking TLR4 signaling. Ints(ΔPten/ΔPten);Il10(-/-) mice may be studied as a model for early-onset ulcerative colitis and used to identify new therapeutic targets.