A TLR4-interacting peptide inhibits lipopolysaccharide-stimulated inflammatory responses, migration and invasion of colon cancer SW480 cells

Increased Oxidative Stress and Decreased Sirtuin-3 and FOXO3 Expression Following Carotid Artery Intimal Injury in Hyperlipidemic Yucatan Microswine

Hypercholesterolemia is a major risk factor for atherosclerosis as oxidized-low-density lipoproteins (ox-LDL) contribute to the formation of foam cells and inflammation. Increased immune cell infiltration and oxidative stress induce instability of a plaque. Rupture of the unstable plaque precipitates adverse ischemic events. Since reactive oxygen species (ROS) play a critical role in plaque formation and vulnerability, regulating ROS generation may have therapeutic potential. Sirtuins, specifically sirtuin-3 (SIRT3), are antigenic molecules that can reduce oxidative stress by reducing mitochondrial ROS production through epigenetic modulation. Lack of SIRT3 expression is associated with dysregulation of ROS and endothelial function following high-fat high-cholesterol diet. SIRT3 deacetylates FOXO3a (Forkhead transcription factor O subfamily member 3a) and protects mitochondria against oxidative stress which can lead to even further protective anti-oxidizing properties. This study was designed to investigate the association between hyperlipidemia, intimal injury, chronic inflammation, and the expression of NAD-dependent deacetylase SIRT-3, FOXO3, antioxidant genes, and oxidative stress in carotid arteries of hypercholesterolemic Yucatan microswine. We found that intimal injury in hypercholesterolemic state led to increased expression of oxidative stress, inflammation, neointimal hyperplasia, and plaque size and vulnerability, while decreasing anti-oxidative regulatory genes and mediators. The findings suggest that targeting the SIRT3-FOXO3a-oxidative stress pathway will have therapeutic significance.

Involvement of endoplasmic reticulum and histone proteins in immunomodulation by TLR4-interacting SPA4 peptide against Escherichia coli

Pulmonary host defense is critical for the control of lung infection and inflammation. An increased expression and activity of Toll-like receptor 4 (TLR4) induce phagocytic uptake/clearance and inflammation against Gram-negative bacteria. In this study, we addressed the mechanistic aspect of the immunomodulatory activity of the TLR4-interacting SPA4 peptide (amino acid sequence GDFRYSDGTPVNYTNWYRGE) against Escherichia coli. Binding of the SPA4 peptide to bacteria and direct anti-bacterial effects were investigated using flow cytometric, microscopic, and bacteriological methods. The bacterial uptake and inflammatory cytokine response were studied in dendritic cells expressing endogenous basal level of TLR4 or overexpressing TLR4. The subcellular distribution and co-localization of TLR4 and bacteria were investigated by immunocytochemistry. Furthermore, we studied the cellular expression and co-localization of endoplasmic reticulum (ER) molecules (calnexin and ER membrane protein complex subunit 1; EMC1) with lysosomal-associated membrane protein 1 (LAMP1) in cells infected with E. coli and treated with the SPA4 peptide. Simultaneously, the expression of histone H2A protein was quantitated by immunoblotting. Our results demonstrate no binding or direct killing of the bacteria by SPA4 peptide. Instead, it induces the uptake and localization of E. coli in the phagolysosomes for lysis and simultaneously suppresses the secreted levels of TNF-α. Overexpression of TLR4 further augments the pro-phagocytic and anti-inflammatory activity of SPA4 peptide. A time-dependent change in subcellular distribution of TLR4 and an increased co-localization of TLR4 with E. coli in SPA4 peptide-treated cells suggest an enhanced recognition and internalization of bacteria in conjugation with TLR4. Furthermore, an increased co-localization of calnexin and EMC1 with LAMP1 indicates the involvement of ER in pro-phagocytic activity of SPA4 peptide. Simultaneous reduction in secreted amounts of TNF-α coincides with suppressed histone H2A protein expression in the SPA4 peptide-treated cells. These results provide initial insights into the plausible role of ER and histones in the TLR4-immunomodulatory activity of SPA4 peptide against Gram-negative bacteria.

Mechanisms of NLRP3 inflammasome activation and the development of peptide inhibitors

The Nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3), a member of the nucleotide-binding oligomerization domain (NOD) like receptors (NLRs) family, plays an important role in the innate immune response against pathogen invasions. NLRP3 inflammasome consisting of NLRP3 protein, the adapter protein apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD) (ASC), and the effector protein pro-caspase-1, is central to this process. Upon activation, NLRP3 inflammasome initiates the release of inflammatory cytokines and triggers a form of cell death known as pyroptosis. Dysregulation or inappropriate activation of NLRP3 has been implicated in various human diseases, including type 2 diabetes, colitis, depression, and gout. Consequently, understanding the mechanism underlying NLRP3 inflammasome activation is critical for the development of therapeutic drugs. In the pursuit of potential therapeutic agents, peptides present several advantages over small molecules. They offer higher selectivity, increased potency, reduced toxicity, and fewer off-target effects. The advancements in molecular biology have expanded the opportunities for applying peptides in medicine, unlocking their vast medical potential. This review begins by providing a comprehensive summary of recent research progress regarding the mechanisms governing NLRP3 inflammasome activation. Subsequently, we offer an overview of current peptide inhibitors capable of modulating the NLRP3 inflammasome activation pathway.

Inhibitory Effects of Chlorogenic Acid Containing Green Coffee Bean Extract on Lipopolysaccharide-Induced Inflammatory Responses and Progression of Colon Cancer Cell Line

An inflammatory response, related to colorectal cancer (CRC) progression, is a major subsequent result of bacterial infection following CRC surgery and should be of serious concern. Lipopolysaccharide (LPS), from the bacterial membrane, is a vital mediator of this event through binding with a Toll-like receptor 4 (TLR4) and activating through NF-κB in CRC. To identify a novel inhibitor of LPS-induced colon cancer cells (SW480), green coffee bean extract (GBE) was investigated. Ethyl acetate insoluble fraction (EIF) was mainly collected from GBE and classified as chlorogenic acid (CGA)-rich fractions. EIF and CGA inhibited TLR4 expression in LPS-induced SW480 cells. However, EIF was more dominant than CGA, via inhibition of expression and secretion of several associated mediators in inflammatory responses and CRC metastasis through NF-κB inactivation, which resulted in the abrogation of CRC migration and invasion. Thus, CGA-rich fraction from GBE can be further developed as an alternative treatment, coupled with CRC surgical treatment, to increase therapeutic efficiency and survival rate.

Construction of Probiotic Double-Layered Multinucleated Microcapsules Based on Sulfhydryl-Modified Carboxymethyl Cellulose Sodium for Increased Intestinal Adhesion of Probiotics and Therapy for Intestinal Inflammation Induced by Escherichia coli O157:H7

The decreased number of viable bacteria and the ability of Bifidobacterium to adhere to and colonize the gut in the gastrointestinal environment greatly limit their efficacy. To solve this problem, thiolated carboxymethyl cellulose sodium (CMC) probiotic double-layered multinucleated microcapsules with Bifidobacterium adolescentis FS2-3 in the inner layer and Bacillus subtilis SN15-2 embedded in the outer layers were designed. First, the viable counts and release rates of microcapsules were examined by in vitro simulated digestion assays, and it was found that microcapsules were better protected from gastrointestinal digestion than the controls. Compared with free Bifidobacterium strains, double-layered multinucleated microcapsules have higher viable bacterial survival rates and storage stability. Second, through in vitro rheology, tensile tests, isotherm titration calorimetry, and adhesion tests, it was observed that thiolated CMC could enhance the strong interaction of Bifidobacterium with intestinal mucus and significantly promote the proliferation and growth of probiotics. Finally, double-layered multinucleated microcapsules containing B. adolescentis FS2-3 and B. subtilis SN15-2 modified with sulfhydryl-modified CMC were studied in the intestine. Alleviation of Escherichia coli O157:H7 induced intestinal inflammation. The results showed that microencapsulation could significantly increase the colon content of Bifidobacterium, relieve intestinal inflammation symptoms in mice with bacterial enteritis, and repair the intestinal microbiota disorder caused by inflammation. The probiotic double-layered multinucleated microcapsules prepared in this study can improve the survival rate of probiotics and promote proliferation, adhesion, and colonization of probiotics.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Effects of Para-Toluenesulfonamide on Canine Melanoma Xenotransplants in a BALB/c Nude Mouse Model

The pharmacological pathway of para-toluenesulfonamide (PTS) restricts the kinase activity of the mammalian target of rapamycin, potentially leading to reductions in cell division, cell growth, cell proliferation, and inflammation. These pathways have a critical effect on tumorigenesis. We aimed to examine the antitumor effect of PTS or PTS combined with cisplatin on canine melanoma implanted in BALB/c nude mice by estimating tumor growth, apoptosis expression, inflammation, and metastasis. The mice were randomly divided into four groups: control, cisplatin, PTS, and PTS combined with cisplatin. Mice treated with PTS or PTS combined with cisplatin had retarded tumor growth and increased tumor apoptosis through the enhanced expression of cleaved caspase 3 and extracellular signal-regulated kinase phosphorylation, decreased inflammatory cytokine levels, reduced inflammation-related factors, enhanced anti-inflammation-related factors, and inhibition of metastasis-related factors. Mice treated with PTS combined with cisplatin exhibited significantly retarded tumor growth, reduced tumor size, and increased tumor inhibition compared with those treated with cisplatin or PTS alone. PTS or PTS combined with cisplatin could retard canine melanoma growth and inhibit tumorigenesis. PTS and cisplatin were found to have an obvious synergistic tumor-inhibiting effect on canine melanoma. PTS alone and PTS combined with cisplatin may be antitumor agents for canine melanoma treatment.

AKR1B10 accelerates the production of proinflammatory cytokines via the NF-κB signaling pathway in colon cancer

Aldo-keto reductase family one, member B10 (AKR1B10) has been reported to be involved in the tumorigenesis of various cancers. It has been reported that colorectal cancer is closely associated with chronic inflammation, but the underlying molecular mechanisms are still elusive. In our study, we evaluated the relationship between AKR1B10 expression and clinicopathological characteristics of colon cancer and showed that AKR1B10 expression was significantly correlated with the T stage and clinical stage of colon cancer. Knockdown of AKR1B10 significantly decreased the expression of the inflammatory cytokines IL1α and IL6 induced by lipopolysaccharide by inhibiting the NF-κB signaling pathway. Furthermore, AKR1B10 depends on its reductase activity to affect the NF-κB signaling pathway and subsequently affect the production of inflammatory cytokines. In addition, knockdown of AKR1B10 effectively reduced cell proliferation and clonogenic growth, indicating the biological role of AKR1B10 in colon cancer. Together, our findings provide important insights into a previously unrecognized role of AKR1B10 in colon cancer.

Effects of SPA4 peptide on lipopolysaccharide-disrupted lung epithelial barrier, injury, and function in a human cell system and mouse model of lung injury

Disrupted epithelial barrier, fluid accumulation, inflammation, and compromised physiology are hallmarks of lung injury. Here we investigated the structural stability of the Toll-like receptor-4 (TLR4)-interacting SPA4 peptide, its effect on Pseudomonas aeruginosa lipopolysaccharide (LPS)-disrupted epithelial barrier in a human cell system, and lung injury markers in a mouse model of LPS-induced lung inflammation. The structural properties of SPA4 peptide were investigated using circular dichroism and UV-VIS spectroscopy. The transepithelial electrical resistance (TEER), an indicator of barrier function, was measured after the cells were challenged with 1 μg/ml LPS and treated with 10 or 100 μM SPA4 peptide. The expression and localization of tight junction proteins were studied by immunoblotting and immunocytochemistry, respectively. Mice were intratracheally challenged with 5 μg LPS per g body weight and treated with 50 μg SPA4 peptide. The lung wet/dry weight ratios or edema, surfactant protein-D (SP-D) levels in serum, lung function, tissue injury, body weights, and temperature, and survival were determined as study parameters. The spectroscopy results demonstrated that the structure was maintained among different batches of SPA4 peptide throughout the study. Treatment with 100 μM SPA4 peptide restored the LPS-disrupted epithelial barrier, which correlated with the localization pattern of Zonula Occludens (ZO)-1 and occludin proteins. Correspondingly, SPA4 peptide treatment helped suppress the lung edema and levels of serum SP-D, improved some of the lung function parameters, and reduced the mortality risk against LPS challenge. Our results suggest that the anti-inflammatory activity of the SPA4 peptide facilitates the resolution of lung pathology.

The Role of Toll-like Receptors (TLRs) Mediated Inflammation in Pancreatic Cancer Pathophysiology

Pancreatic cancer (PC) is one of the most lethal forms of cancer, characterized by its aggressiveness and metastatic potential. Despite significant improvements in PC treatment and management, the complexity of the molecular pathways underlying its development has severely limited the available therapeutic opportunities. Toll-like receptors (TLRs) play a pivotal role in inflammation and immune response, as they are involved in pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Activation of TLRs initiates a signaling cascade, which in turn, leads to the transcription of several genes involved in inflammation and anti-microbial defense. TLRs are also deregulated in several cancers and can be used as prognostic markers and potential targets for cancer-targeted therapy. In this review we discuss the current knowledge about the role of TLRs in PC progression, focusing on the available TLRs-targeting compounds and their possible use in PC therapy.

Gamma-Oryzanol-Rich Fraction from Purple Rice Extract Attenuates Lipopolysaccharide-Stimulated Inflammatory Responses, Migration and VEGFA Production in SW480 Cells via Modulation of TLR4 and NF-κB Pathways

Inflammatory response facilitating colorectal cancer (CRC) progression is a serious event following operative infection, which can occur in CRC patients. This event is mainly mediated by bacterial lipopolysaccharide (LPS), via a toll like receptor 4 (TLR4) and NF-κB. Hexane soluble fraction (HSF) from purple rice extract (PRE) has been identified as a γ-oryzanol (OR)-rich fraction. Recently, HSF possessed inhibitory effect of LPS-stimulated metastasis of human colon cancer SW480 cells, however the related mechanism was unknown. Thus, this study aimed to investigate the effect of HSF on inflammatory response-associated cancer progression of LPS-stimulated SW480 cells. The various inflammatory mediators, vascular endothelial growth factor-A (VEGFA) and related pathways were evaluated by Western blot and ELISA. Furthermore, cell migration was also determined by migration assays. Of all, HSF seemed to be stronger than OR to attenuate the responsiveness of LPS on various inflammatory mediators, which was related to an obvious reduction of cancer cell migration as well as indistinct disruption on VEGFA production in SW480 cells, via downregulation of TLR4 and NF-κB. Therefore, OR-rich fraction from PRE, against the subsequent inflammatory response and CRC progression following surgery, which could be combined with conventional treatments to increase the survival rate.

Mechanism of Anti-Inflammatory Activity of TLR4-Interacting SPA4 Peptide

The TLR4-interacting SPA4 peptide suppresses inflammation. We assessed the structural and physicochemical properties and binding of SPA4 peptide to TLR4-MD2. We also studied the changes at the whole transcriptome level, cell morphology, viability, secreted cytokines and chemokines, and cell influx in cell systems and mouse models challenged with LPS and treated with SPA4 peptide. Our results demonstrated that the SPA4 peptide did not alter the cell viability and size and only moderately affected the transcriptome of the cells. Computational docking and rendering suggested that the SPA4 peptide intercalates with LPS-induced TLR4-MD2 complex. Results with alanine mutations of D-2 amino acid and NYTXXXRG-12-19 motif of SPA4 peptide suggested their role in binding to TLR4 and in reducing the cytokine response against LPS stimulus. Furthermore, therapeutically administered SPA4 peptide significantly suppressed the secreted levels of cytokines and chemokines in cells and bronchoalveolar lavage fluids of LPS-challenged mice. The results suggest that the SPA4 peptide intercalates with LPS-induced TLR4 complex and signaling for the suppression of inflammation.

Molecular Communication Between Neuronal Networks and Intestinal Epithelial Cells in Gut Inflammation and Parkinson's Disease

Intestinal symptoms, such as nausea, vomiting, and constipation, are common in Parkinson's disease patients. These clinical signs normally appear years before the diagnosis of the neurodegenerative disease, preceding the occurrence of motor manifestations. Moreover, it is postulated that Parkinson's disease might originate in the gut, due to a response against the intestinal microbiota leading to alterations in alpha-synuclein in the intestinal autonomic nervous system. Transmission of this protein to the central nervous system is mediated potentially via the vagus nerve. Thus, deposition of aggregated alpha-synuclein in the gastrointestinal tract has been suggested as a potential prodromal diagnostic marker for Parkinson's disease. Interestingly, hallmarks of chronic intestinal inflammation in inflammatory bowel disease, such as dysbiosis and increased intestinal permeability, are also observed in Parkinson's disease patients. Additionally, alpha-synuclein accumulations were detected in the gut of Crohn's disease patients. Despite a solid association between neurodegenerative diseases and gut inflammation, it is not clear whether intestinal alterations represent cause or consequence of neuroinflammation in the central nervous system. In this review, we summarize the bidirectional communication between the brain and the gut in the context of Parkinson's disease and intestinal dysfunction/inflammation as present in inflammatory bowel disease. Further, we focus on the contribution of intestinal epithelium, the communication between intestinal epithelial cells, microbiota, immune and neuronal cells, as well as mechanisms causing alterations of epithelial integrity.

Surfactant protein A reduces TLR4 and inflammatory cytokine mRNA levels in neonatal mouse ileum

Levels of intestinal toll-like receptor 4 (TLR4) impact inflammation in the neonatal gastrointestinal tract. While surfactant protein A (SP-A) is known to regulate TLR4 in the lung, it also reduces intestinal damage, TLR4 and inflammation in an experimental model of necrotizing enterocolitis (NEC) in neonatal rats. We hypothesized that SP-A-deficient (SP-A-/-) mice have increased ileal TLR4 and inflammatory cytokine levels compared to wild type mice, impacting intestinal physiology. We found that ileal TLR4 and proinflammatory cytokine levels were significantly higher in infant SP-A-/- mice compared to wild type mice. Gavage of neonatal SP-A-/- mice with purified SP-A reduced ileal TLR4 protein levels. SP-A reduced expression of TLR4 and proinflammatory cytokines in normal human intestinal epithelial cells (FHs74int), suggesting a direct effect. However, incubation of gastrointestinal cell lines with proteasome inhibitors did not abrogate the effect of SP-A on TLR4 protein levels, suggesting that proteasomal degradation is not involved. In a mouse model of experimental NEC, SP-A-/- mice were more susceptible to intestinal stress resembling NEC, while gavage with SP-A significantly decreased ileal damage, TLR4 and proinflammatory cytokine mRNA levels. Our data suggests that SP-A has an extrapulmonary role in the intestinal health of neonatal mice by modulating TLR4 and proinflammatory cytokines mRNA expression in intestinal epithelium.

The role of toll-like receptor 4 (TLR4) in cancer progression: A possible therapeutic target?

The toll-like receptor (TLR) family consists of vital receptors responsible for pattern recognition in innate immunity, making them the core proteins involved in pathogen detection and eliciting immune responses. The most studied member of this family, TLR4, has been the center of attention regarding its contributory role in many inflammatory diseases including sepsis shock and asthma. Notably, mounting pieces of evidence have proved that this receptor is aberrantly expressed on the tumor cells and the tumor microenvironment in a wide range of cancer types and it is highly associated with the initiation of tumorigenesis as well as tumor progression and drug resistance. Cancer therapy using TLR4 inhibitors has recently drawn scientists' attention, and the promising results of such studies may pave the way for more investigation in the foreseeable future. This review will introduce the key proteins of the TLR4 pathway and how they interact with major growth factors in the tumor microenvironment. Moreover, we will discuss the many aspects of tumor progression affected by the activation of this receptor and provide an overview of the recent therapeutic approaches using various TLR4 antagonists.

Inhibitory effect of a gamma-oryzanol-rich fraction from purple rice extract on lipopolysaccharide-induced metastasis in human colon cancer cells

The incidence of colon cancer recurrence and metastasis is known to increase as an adverse effect related to postoperative infection. Lipopolysaccharide or LPS, which is derived from gram-negative bacteria, is a key inducer of inflammatory-related tumor metastasis. Although there are numerous known biological effects of purple rice extract (PRE), its protective effect on colon metastasis was unknown. This study first evaluated the effects of hexane soluble fraction (HSF) or γ-oryzanol-rich fraction of PRE on LPS-induced colon cancer adhesion and invasion, which was accomplished using adhesive and invasive assay. Gelatin zymography was also utilized for gelatinase activity and secretion. Its chelating activity was also further analyzed by reverse gelatin zymography with zinc chloride. The study findings support the synergistic effect of HSF in protection against adverse events from LPS-induced colon cancer metastasis, as shown by effects on adhesive and invasive ability as well as matrix metalloproteinase-2 secretion and activity. PRACTICAL APPLICATIONS: Bacterial infection is still one of the main adverse events following abdominal cancer surgery and is associated with an increased incidence of colon cancer metastasis. Lipopolysaccharide (LPS) is a major component of this pathogen-mediated response. This first study investigated the efficiency of a gamma-oryzanol (OR) rich fraction, collected from purple rice extract (PRE), against LPS-induced colon cancer metastasis that occurs via three main steps; adhesion to the extracellular matrix, the secretion, and activity of gelatinase and further tissue invasion. The acquired data supported the role of an OR-rich fraction from PRE as a potential inhibitor to LPS-induced colon cancer progression. This finding, related to PRE, could be further developed to create a new adjunctive treatment to reduce operative complications related to bowel cancer surgery as well as increasing the value of this crop in Thailand.

Epigenetic effect of folic acid (FA) on the gene proximal promoter area and mRNA expression of chicken B cell as antigen presenting cells

1. This study evaluated and characterised the effect of folic acid (FA) on chromosomal DNA methylation and the epigenetic result on gene expression control mechanisms in chicken B cells as a model of antigen presenting cells. 2. After FA supplementation, the methylation pattern on the proximal promoter area and mRNA expression of toll-like receptor (TLR) 2b, TLR4, B cell receptor (BCR) immunoglobulin (Ig) β and major histocompatibility complex (MHC) II β chain genes in chicken B cells was observed 3. Chicken B cell line (DT40) cultures were incubated with 0, 1.72 or 3.96 mM of FA for 4 and 8 h and samples were taken at specific time points. After 4 h of incubation, cells were challenged with 0, 1 or 10 µg/ml of lipopolysaccharide (LPS) and samples were collected 4 h post-challenge. 4. FA supplementation modified the methylation patterns of the proximal promoter regions of TLR4, Igß, and MHCII ß chain at 4 and 8 hours of incubation; however, the single CpG dinucleotide of TLR2b remained methylated regardless of the treatment. 5. A positive association was found between FA concentration and percentage DNA methylation on the promoter area of Igβ and TLR2b. However, there was a negative association between FA and MHCII β chain. 6. There were downregulatory effects in TLR4, Igß and MHCII ß chain gene expression after 8 h of incubation, nut not at 4 h. Although incubation time did not affect TLR2b gene expression, FA concentration did, whereby it increased TLR2b expression at 1.72 mM FA (P < 0.05). 7. LPS significant downregulated TLR2b expression, while an interaction between FA and LPS concentration affected TLR4 and Igβ gene expression. 8. In conclusion, the results showed that FA can have an immunomodulatory effect on chicken B cells, possibly affecting their ability to both recognise antigens through the TLR and BCR pathways, and to present it via the MHCII presentation pathway.

Lung and general health effects of Toll-like receptor-4 (TLR4)-interacting SPA4 peptide

Background

A surfactant protein-A-derived peptide, which we call SPA4 peptide (amino acids: GDFRYSDGTPVNYTNWYRGE), alleviates lung infection and inflammation. This study investigated the effects of intratracheally administered SPA4 peptide on systemic, lung, and health parameters in an outbred mouse strain, and in an intratracheal lipopolysaccharide (LPS) challenge model.

Methods

The outbred CD-1 mice were intratracheally administered with incremental doses of SPA4 peptide (0.625–10 μg/g body weight) once every 24 h, for 3 days. Mice left untreated and those treated with vehicle were included as controls. Mice were euthanized after 24 h of last administration of SPA4 peptide. In order to assess the biological activity of SPA4 peptide, C57BL6 mice were intratracheally challenged with 5 μg LPS/g body weight and treated with 50 μg SPA4 peptide via intratracheal route 1 h post LPS-challenge. Mice were euthanized after 4 h of LPS challenge. Signs of sickness and body weights were regularly monitored. At the time of necropsy, blood and major organs were harvested. Blood gas and electrolytes, serum biochemical profiles and SPA4 peptide-specific immunoglobulin G (IgG) antibody levels, and common lung injury markers (levels of total protein, albumin, and lactate, lactate dehydrogenase activity, and lung wet/dry weight ratios) were determined. Lung, liver, spleen, kidney, heart, and intestine were examined histologically. Differences in measured parameters were analyzed among study groups by analysis of variance test.

Results

The results demonstrated no signs of sickness or changes in body weight over 3 days of treatment with various doses of SPA4 peptide. It did not induce any major toxicity or IgG antibody response to SPA4 peptide. The SPA4 peptide treatment also did not affect blood gas, electrolytes, or serum biochemistry. There was no evidence of injury to the tissues and organs. However, the SPA4 peptide suppressed the LPS-induced lung inflammation.

Conclusions

These findings provide an initial toxicity profile of SPA4 peptide. Intratracheal administration of escalating doses of SPA4 peptide does not induce any significant toxicity at tissue and organ levels. However, treatment with a dose of 50 μg SPA4 peptide, comparable to 2.5 μg/g body weight, alleviates LPS-induced lung inflammation.

Cathelicidins Modulate TLR-Activation and Inflammation

Cathelicidins are short cationic peptides that are part of the innate immune system. At first, these peptides were studied mostly for their direct antimicrobial killing capacity, but nowadays they are more and more appreciated for their immunomodulatory functions. In this review, we will provide a comprehensive overview of the various effects cathelicidins have on the detection of damage- and microbe-associated molecular patterns, with a special focus on their effects on Toll-like receptor (TLR) activation. We review the available literature based on TLR ligand types, which can roughly be divided into lipidic ligands, such as LPS and lipoproteins, and nucleic-acid ligands, such as RNA and DNA. For both ligand types, we describe how direct cathelicidin-ligand interactions influence TLR activation, by for instance altering ligand stability, cellular uptake and receptor interaction. In addition, we will review the more indirect mechanisms by which cathelicidins affect downstream TLR-signaling. To place all this information in a broader context, we discuss how these cathelicidin-mediated effects can have an impact on how the host responds to infectious organisms as well as how these effects play a role in the exacerbation of inflammation in auto-immune diseases. Finally, we discuss how these immunomodulatory activities can be exploited in vaccine development and cancer therapies.

Egg-Derived Tripeptide IRW Attenuates LPS-Induced Osteoclastogenesis in RAW 264.7 Macrophages via Inhibition of Inflammatory Responses and NF-κB/MAPK Activation

Excessive bone resorption, because of increased osteoclastic activity, is a key underlying cause of osteolytic disorders. Lipopolysaccharide (LPS) is a potent factor to stimulate osteoclastic activity by inducing inflammatory stress. An egg-derived tripeptide IRW (Ile-Arg-Trp) was previously shown to exert anti-inflammatory activity. The overall objective of this study was to investigate the effect of IRW on inhibiting LPS-induced osteoclastogenesis and inflammatory bone resorption in the mouse macrophage RAW 264.7 cells. IRW (25 and 50 μM) significantly inhibited the LPS-induced osteoclast formation and resorptive activity. Meanwhile, IRW significantly suppressed the LPS-induced expression of TNF-α, IL-6, iNOS, COXII, NO, and PGE2. Furthermore, IRW regulated a group of osteoclastogenesis-associated factors (TRAF6, c-Fos, NFATc1, and cathepsin K) because of the inhibition of LPS-activated NF-κB and MAPK pathways. In conclusion, our study suggested the ability of IRW to prevent LPS-induced inflammatory bone resorption activity via the inhibition of inflammatory responses and the activation of osteoclastogenesis-associated signaling pathways.

TLR4-interacting SPA4 peptide improves host defense and alleviates tissue injury in a mouse model of Pseudomonas aeruginosa lung infection

Interaction between surfactant protein-A (SP-A) and toll-like receptor (TLR)4 plays a critical role in host defense. In this work, we studied the host defense function of SPA4 peptide (amino acids GDFRYSDGTPVNYTNWYRGE), derived from the TLR4-interacting region of SP-A, against Pseudomonas aeruginosa. We determined the binding of SPA4 peptide to live bacteria, and its direct antibacterial activity against P. aeruginosa. Pro-phagocytic and anti-inflammatory effects were investigated in JAWS II dendritic cells and primary alveolar macrophages. The biological relevance of SPA4 peptide was evaluated in a mouse model of acute lung infection induced by intratracheal challenge with P. aeruginosa. Our results demonstrate that the SPA4 peptide does not interact with or kill P. aeruginosa when cultured outside the host. The SPA4 peptide treatment induces the uptake and localization of bacteria in the phagolysosomes of immune cells. At the same time, the secreted amounts of TNF-α are significantly reduced in cell-free supernatants of SPA4 peptide-treated cells. In cells overexpressing TLR4, the TLR4-induced phagocytic response is maintained, but the levels of TLR4-stimulated TNF-α are reduced. Furthermore, our results demonstrate that the therapeutic administration of SPA4 peptide reduces bacterial burden, inflammatory cytokines and chemokines, intracellular signaling, and lactate levels, and alleviates lung edema and tissue damage in P. aeruginosa-infected mice. Together, our results suggest that the treatment with SPA4 peptide can help control the bacterial burden, inflammation, and tissue injury in a P. aeruginosa lung infection model.

NF-κB p65 and p105 implicate in interleukin 1β-mediated COX-2 expression in melanoma cells

Inflammatory and microenvironmental factors produced by cancer cells are thought to directly or indirectly promote cancer cell growth. Prostaglandins, including prostaglandin E2, have key roles as a microenvironment factor in influencing the development of tumors, and are produced by the rate limiting enzyme cyclooxygenase 2 (COX-2). In this study, we used canine melanoma cells treated with the proinflammatory cytokine interleukin 1β (IL-1β) and investigated the transcriptional factor nuclear factor-κB (NF-κB) signaling in IL-1β-induced COX-2 expression. IL-1β induced prostaglandin E2 release and COX-2 mRNA expression in a time- and dose-dependent manner. In the cells treated with the NF-κB inhibitors BAY11-7082 and TPC-1, IL-1β-mediated prostaglandin E2 release and COX-2 mRNA expression were inhibited. IL-1β also provoked phosphorylation of p65/RelA and p105/NF-κB1, which are members of the NF-κB families. The IL-1β-induced phosphorylation of p65 and p105 was attenuated in the presence of both NF-κB inhibitors. In melanoma cells transfected with siRNA of p65 or p105, IL-1β-mediated COX-2 mRNA expression was inhibited. These findings suggest that canonical activation of NF-κB signaling plays a crucial role for inflammatory states in melanoma cells.

Two protein-coding genes act as a novel clinical signature to predict prognosis in patients with ovarian serous cystadenocarcinoma

Ovarian cancer is the seventh most common type of cancer and the eighth most common cause of cancer-associated mortality among women. A number of studies have hypothesized that the expression status of certain genes may be used to predict prognosis in ovarian cancer. In the present study, the RNA expression data from next-generation sequencing and the clinical information of 413 patients from The Cancer Genome Atlas dataset was downloaded to identify the association between gene-expression level and the survival time of the patients with ovarian serous cystadenocarcinoma. A five-gene model was predicted to be significantly associated with patient survival in ovarian serous cystadenocarcinoma by using random survival forests variable hunting algorithm and Cox analysis. A total of two genes, mesencephalic astrocyte-derived neurotrophic factor and dedicator of cytokinesis 11, of the predicted five genes demonstrated positive expression in the ovarian serous cystadenocarcinoma cancer tissues by polymerase chain reaction analysis. Kaplan-Meier and Receiver Operating Characteristic analysis confirmed that the model of the two genes exhibited high sensitivity and specificity to predict the prognostic survival of patients. In conclusion, the expression of the two genes in the two-gene model was associated with the prognostic outcomes of patients with ovarian serous cystadenocarcinoma; the model demonstrated potential as a novel prognostic indicator, which may have important clinical significance.

Emerging Mechanisms of Innate Immunity and Their Translational Potential in Inflammatory Bowel Disease

Activation of the innate immune system through pattern-recognition receptor (PRR) signaling plays a pivotal role in the early induction of host defense following exposure to pathogens. Loss of intestinal innate immune regulation leading aberrant immune responses has been implicated in the pathogenesis of inflammatory bowel disease (IBD). The precise role of PRRs in gut inflammation is not well understood, but considering their role as bacterial sensors and their genetic association with IBD, they likely contribute to dysregulated immune responses to the commensal microbiota. The purpose of this review is to evaluate the emerging functions of PRRs including their functional cross-talk, how they respond to mitochondrial damage, induce mitophagy or autophagy, and influence adaptive immune responses by interacting with the antigen presentation machinery. The review also summarizes some of the recent attempts to harness these pathways for therapeutic approaches in intestinal inflammation.

Heterogeneity of colon cancer: from bench to bedside

The large bowel shows biomolecular, anatomical and bacterial changes that proceed from the proximal to the distal tract. These changes account for the different behaviour of colon cancers arising from the diverse sides of the colon-rectum as well as for the sensitivity to the therapy, including immunotherapy. The gut microbiota plays an important role in the modulation of the immune response and differs between the right colon cancer and the left colorectal cancer. The qualitative and quantitative difference of the commensal bacteria between the right side and the left side induces epigenetic changes in the intestinal epithelial cells as well as in the resident immune population. The second player in the pathological homeostasis of colorectal cancer is the differences of the genetic features of cancer cells and the different effects that microsatellite instability, chromosomal instability and the CpG island methylator phenotype induce on the immunological organisation of the tumour microenvironment. The third player is the immunological composition of the tumour microenvironment, which changes under the influence of both genetic structures and gut microbiota. All these three players influence each other. This review describes these three aspects, highlights their interactions and discusses data from reported clinical trials.

Surfactant Protein A Enhances Constitutive Immune Functions of Clathrin Heavy Chain and Clathrin Adaptor Protein 2

NF-κB transcription factors are key regulators of pulmonary inflammatory disorders and repair. Constitutive lung cell type- and microenvironment-specific NF-κB/inhibitor κBα (IκB-α) regulation, however, is poorly understood. Surfactant protein (SP)-A provides both a critical homeostatic and lung defense control, in part by immune instruction of alveolar macrophages (AMs) via clathrin-mediated endocytosis. The central endocytic proteins, clathrin heavy chain (CHC) and the clathrin adaptor protein (AP) complex AP2, have pivotal alternative roles in cellular homeostasis that are endocytosis independent. Here, we dissect endocytic from alternative functions of CHC, the α-subunit of AP2, and dynamin in basal and SP-A-modified LPS signaling of macrophages. As revealed by pharmacological inhibition and RNA interference in primary AMs and RAW264.7 macrophages, respectively, CHC and α-adaptin, but not dynamin, prevent IκB-α degradation and TNF-α release, independent of their canonical role in membrane trafficking. Kinetics studies employing confocal microscopy, Western analysis, and immunomagnetic sorting revealed that SP-A transiently enhances the basal protein expression of CHC and α-adaptin, depending on early activation of protein kinase CK2 (former casein kinase II) and Akt1 in primary AMs from rats, SP-A(+/+), and SP-A(-/-) mice, as well as in vivo when intratracheally administered to SP-A(+/+) mice. Constitutive immunomodulation by SP-A, but not SP-A-mediated inhibition of LPS-induced NF-κB activity and TNF-α release, requires CHC, α-adaptin, and dynamin. Our data demonstrate that endocytic proteins constitutively restrict NF-κB activity in macrophages and provide evidence that SP-A enhances the immune regulatory capacity of these proteins, revealing a previously unknown pathway of microenvironment-specific NF-κB regulation in the lung.

LPS promotes resistance to TRAIL-induced apoptosis in pancreatic cancer

Background

Though TRAIL has been hailed as a promising drug for tumour treatment, it has been observed that many tumour cells have developed escape mechanisms against TRAIL-induced apoptosis. As a receptor of LPS, TLR 4, which is expressed on a variety of cancer cells, can be associated with TRAIL-resistance of tumour cells and tumour progression as well as with the generation of an anti-tumour immune response.

Methods

In this study, the sensitivity to TRAIL-induced apoptosis as well as the influence of LPS-co-stimulation on the cell viability of the pancreatic cancer cell lines PANC-1, BxPC-3 and COLO 357 was examined by FACS analyses and a cell viability assay. Subsequently, the expression of TRAIL-receptors was detected via FACS analyses. Levels of osteoprotegerin (OPG) were also determined using an enzyme-linked immunosorbent assay.

Results

PANC-1 cells were shown to be resistant to TRAIL-induced apoptosis. This was accompanied by significantly increased osteoprotegerin levels and a significantly decreased expression of DR4.

In contrast, TRAIL significantly induced apoptosis in COLO 357 cells and to a lesser degree in BxPC-3 cells. Co-stimulation of COLO 357 as well as BxPC-3 cells combining TRAIL and LPS resulted in a significant decrease in TRAIL-induced apoptosis. In COLO 357 cells TRAIL-stimulation decreased the levels of OPG thereby not altering the expression of the TRAIL-receptors 1–4 resulting in a high susceptibility to TRAIL-induced apoptosis. Co-stimulation with LPS and TRAIL completely reversed the effect of TRAIL on OPG levels reaching a 2-fold increase beyond the level of non-stimulated cells resulting in a lower susceptibility to apoptosis.

In BxPC-3, TRAIL stimulation decreased the expression of DR4 and significantly increased the decoy receptors TRAIL-R3 and TRAIL-R4 leading to a decrease in TRAIL-induced apoptosis. OPG levels remained unchanged. Co-stimulation with TRAIL and LPS further enhanced the changes in TRAIL-receptor-expression promoting apoptosis resistance.

Conclusions

Here it has been shown that TRAIL-resistance in pancreatic cancer cells can be mediated by the inflammatory molecule LPS as well as by different expression patterns of functional and non-functional TRAIL-receptors.

Investigation of cationicity and structure of pseudin-2 analogues for enhanced bacterial selectivity and anti-inflammatory activity

Pseudin-2 (Ps), isolated from the frog Pseudis paradoxa, exhibits potent antibacterial activity and cytotoxicity. To develop antimicrobial peptides with anti-inflammatory activity and low cytotoxicity, we designed Ps analogues with Lys substitutions, resulting in elevated amphipathic α-helical structure and cationicity. We further substituted Gly¹¹ with Pro (Ps-P analogues) to increase bacterial cell selectivity. Ps analogues retained antimicrobial activity and exhibited reduced cytotoxicity, whereas Ps-P analogues exhibited lower cytotoxicity and antimicrobial activity. Tertiary structures revealed that Ps has a linear α-helix from Leu² to Glu²⁴, whereas Ps-P has a bend at Pro¹¹ between two short α-helixes. Using various biophysical experiments, we found that Ps analogues produced much higher membrane depolarization than Ps-P analogues, whereas Ps-P analogues may penetrate bacterial cell membranes. Ps and its analogue Ps-K18 exhibited potent anti-inflammatory activity in LPS-stimulated RAW264.7 and mouse dendritic cells via a mechanism involving the Toll-like receptor 4 (TLR4) pathway. These activities may arise from their direct inhibition of the formation of TLR4-MD-2_LPS complex, implying that amphipathic α-helical structure with an optimum balance between enhanced cationicity and hydrophobicity may be essential for their anti-inflammatory activity. The bent structure provided by Pro substitution plays an important role in enhancing bacterial cell selectivity and cell penetration.

Therapeutic implication of 'Iturin A' for targeting MD-2/TLR4 complex to overcome angiogenesis and invasion

Tumor angiogenesis and invasion are deregulated biological processes that drive multistage transformation of tumors from a benign to a life-threatening malignant state activating multiple signaling pathways including MD-2/TLR4/NF-κB. Development of potential inhibitors of this signaling is emerging area for discovery of novel cancer therapeutics. In the current investigation, we identified Iturin A (A lipopeptide molecule from Bacillus megaterium) as a potent inhibitor of angiogenesis and cancer invasion by various in vitro and in vivo methods. Iturin A was found to suppress VEGF, a powerful inducer of angiogenesis and key player in tumor invasion, as confirmed by ELISA, western blot and real time PCR. Iturin A inhibited endothelial tube arrangement, blood capillary formation, endothelial sprouting and vascular growth inside the matrigel. In addition, Iturin A inhibited MMP-2/9 expression in MDA-MB-231 and HUVEC cells. Cancer invasion, migration and colony forming ability were significantly hampered by Iturin A. Expressions of MD-2/TLR4 and its downstream MyD88, IKK-α and NF-κB were also reduced in treated MDA-MB-231 and HUVEC cells. Western blot and immunofluorescence study showed that nuclear accumulation of NF-κB was hampered by Iturin A. MD-2 siRNA or plasmid further confirmed the efficacy of Iturin A by suppressing MD-2/TLR4 signaling pathway. The in silico docking study showed that the Iturin A interacted well with the MD-2 in MD-2/TLR4 receptor complex. Conclusively, inhibition of MD-2/TLR4 complex with Iturin A offered strategic advancement in cancer therapy.

Interactions between colon cancer cells and tumor-infiltrated macrophages depending on cancer cell-derived colony stimulating factor 1

Tumor-infiltrated macrophages were potential targets of the immune therapy for patients with colon cancer. Colony stimulating factor 1 (CSF1) is a primary chemoattractant and functional regulator for macrophages, and therefore would be a feasible intervention for the macrophage-targeting therapeutics. However, the expression of CSF1 in colon cancer microenvironment and its roles in cancer development is largely unknown. In the present study, we found that CSF1 was over-expressed exclusively in colon cancer cells and was correlated with macrophages infiltration. The high CSF1 expression and macrophages infiltration were related to the tumor-node-metastasis (TNM) stage of colon cancer, and suggested to be positively associated with survival of colon cancer patients. In the in vitro studies based on an indirect Transwell system, we found that co-culture with macrophage promoted CSF1 production in colon cancer cells. Further investigation on regulatory mechanisms suggested that CSF1 production in colon cancer cells was dependent on PKC pathway, which was activated by IL-8, mainly produced by macrophages. Moreover, colon cancer cell-derived CSF1 drove the recruitment of macrophages and re-educated their secretion profile, including the augment of IL-8 production. The mice tumor xenografts study also found that over-expression of CSF1 in colon cancer cells promoted intratumoral infiltration of macrophages, and partially suppressed tumor growth. In all, our results demonstrated that CSF1 was an important factor in the colon cancer microenvironment, involving in the interactions between colon cancer cells and tumor-infiltrated macrophages.

CD90(+) stromal cells are the major source of IL-6, which supports cancer stem-like cells and inflammation in colorectal cancer

IL-6 is a pleiotropic cytokine increased in CRC and known to directly promote tumor growth. Colonic myofibroblasts/fibroblasts (CMFs or stromal cells) are CD90(+) innate immune cells representing up to 30% of normal colonic mucosal lamina propria cells. They are expanded in CRC tumor stroma, where they also known as a cancer associated fibroblasts (CAFs). Cells of mesenchymal origin, such as normal myofibroblasts/fibroblasts, are known to secrete IL-6; however, their contribution to the increase in IL-6 in CRC and to tumor-promoting inflammation is not well defined. Using in situ, ex vivo and coculture analyses we have demonstrated that the number of IL-6 producing CMFs is increased in CRC (C-CMFs) and they represent the major source of IL-6 in T2-T3 CRC tumors. Activity/expression of stem cell markers-aldehyde dehydrogenase and LGR5- was significantly up-regulated in colon cancer cells (SW480, Caco-2 or HT29) cultured in the presence of conditioned medium from tumor isolated C-CMFs in an IL-6 dependent manner. C-CMF and its derived condition medium, but not normal CMF isolated from syngeneic normal colons, induced differentiation of tumor promoting inflammatory T helper 17 cells (Th17) cell responses in an IL-6 dependent manner. Our study suggests that CD90(+) fibroblasts/myofibroblasts may be the major source of IL-6 in T2-T3 CRC tumors, which supports the stemness of tumor cells and induces an immune adaptive inflammatory response (a.k.a. Th17) favoring tumor growth. Taken together our data supports the notion that IL-6 producing CAFs (a.k.a. C-CMFs) may provide a useful target for treating or preventing CRCs.

Andrographolide inhibits melanoma tumor growth by inactivating the TLR4/NF-κB signaling pathway

The TLR4/NF-κB signaling pathway plays a critical role in tumor progression. Andrographolide (Andro) has been reported to have anticancer activity in multiple types of cancer. However, the pharmacological activities of Andro in melanoma are not completely understood. In this study, we defined the anticancer effects of Andro in melanoma and elucidated its potential mechanisms of action. Our experiments showed that Andro significantly inhibited melanoma tumor growth and metastasis by inducing cell cycle arrest and apoptosis. In addition, Andro significantly inhibited the TLR4/NF-κB signaling pathway. Furthermore, the inactivation of TLR4/NF-κB signaling inhibited the mRNA and protein expression of CXCR4 and Bcl-6, which are antitumor genes. This work provides evidence that the TLR4/NF-κB signaling pathway is a potential therapeutic target and may also be indispensable in the Andro-mediated anticancer effect in melanoma.

Toll-like receptor 4-interacting SPA4 peptide suppresses the NLRP3 inflammasome in response to LPS and ATP stimuli

Inflammation is induced because of interplay among multiple signaling pathways and molecules during infectious and noninfectious tissue injuries. Crosstalk between Toll-like receptor-4 signaling and the neuronal apoptosis inhibitor protein, major histocompatibility class 2 transcription activator, incompatibility locus protein from Podospora anserina, and telomerase-associated protein (NACHT), leucine-rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) inflammasome against pathogen- or damage-associated molecular patterns can cause exaggerated inflammation. We previously established that the Toll-like receptor-4-interacting SPA4 peptide suppresses gram-negative bacterial lipopolysaccharide (Toll-like receptor-4 ligand)-induced nuclear factor-κB and inflammatory response. In the present study, we hypothesized that the SPA4 peptide exerts its anti-inflammatory effects by suppressing the crosstalk between Toll-like receptor-4 signaling and the NLRP3 inflammasome. We evaluated binding of the lipopolysaccharide-ligand to cell-surface Toll-like receptor-4 in the presence or absence of adenosine triphosphate (an NLRP3 inflammasome inducer) by flow cytometry. The expression and activity of NLRP3 inflammasome-related parameters were studied in cells challenged with lipopolysaccharide and adenosine triphosphate using molecular and immunologic methods. The cells were challenged with lipopolysaccharide and treated with SPA4 peptide before (pre-adenosine triphosphate) or after (post-adenosine triphosphate) secondary challenge with adenosine triphosphate. Our data demonstrate that the Toll-like receptor-4-interacting SPA4 peptide does not affect the binding of lipopolysaccharide to Toll-like receptor-4 in the presence or absence of adenosine triphosphate. We also found that the SPA4 peptide inhibits mRNA and cellular protein levels of pro-interleukin-1β and NLRP3, formation of the NLRP3 inflammasome, caspase activity, and release of interleukin-1β. Furthermore, the SPA4 peptide treatment reduced the secreted levels of interleukin-1β from cells overexpressing Toll-like receptor-4 compared with cells expressing the dominant-negative form of Toll-like receptor-4. Together our results suggest that the SPA4 peptide exerts its anti-inflammatory activity by suppressing Toll-like receptor-4-priming of the NLRP3 inflammasome.

Pyruvate kinase M2 accelerates pro-inflammatory cytokine secretion and cell proliferation induced by lipopolysaccharide in colorectal cancer

Surgery-induced inflammation has been associated with cancer recurrence and metastasis in colorectal cancer (CRC). As a constituent of gram-negative bacteria, lipopolysaccharide (LPS) is frequently abundant in the peri-operative window. However, the definite roles of LPS in tumour progression remain elusive. Here we reported that LPS treatment increased PKM expression through activation of NF-κB signalling pathway, and knockdown of PKM reversed LPS-induced TNF-α, IL-1β production and cell proliferation in CRC cells. We further showed that the PKM2 but not PKM1 mediated the pro-inflammatory and proliferative effects of LPS. Interestingly, LPS promoted PKM2 binding to the STAT3 promoter to enhance STAT3 expression and its subsequent nuclear translocation. Depletion of STAT3 decreased PKM2-induced TNF-α and IL-1β expression, indicating that STAT3 mediates the pro-inflammatory effects of PKM2. Furthermore, it is the protein kinase activity but not the pyruvate kinase activity of PKM2 that is required for inflammatory cytokine production. Collectively, our findings reveal the NF-κB-PKM2-STAT3 axis as a novel mechanism for the regulation of TNF-α and IL-1β production and suggest the importance of PKM2 as a key inflammatory mediator in inflammatory microenvironment.

Structure of a TLR4-interacting SPA4 peptide

We have recently identified a Toll-like receptor (TLR4)-interacting SPA4 peptide encoding amino acids: GDFRYSDGTPVNYTNWYRGE, a shorter region of human surfactant protein-A (SP-A). The SPA4 peptide suppressed lipopolysaccharide-induced inflammation (JPET 2011, Innate Immun 2013). In this report, we examined the structure of synthetic SPA4 peptide in solution by circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy. The CD analysis revealed that the SPA4 peptide is composed of ∼35% beta sheet and <5% alpha helix. We used solution NMR to solve the structure of the SPA4 peptide. We calculated NMR structures using Nuclear Overhauser Enhancement (NOE) distance restraints. The superposition of the low energy structures indicated that the central 6-14 amino acids "SDGTPVNYT" of the 20mer SPA4 peptide form a turn, and amino acids on either side (GDFRY and NWYRGE) conform to flexible arms. Furthermore, thermal denaturation experiments demonstrated the structural flexibility of the peptide. The NMR structures of the SPA4 peptide align well with the homologous region within the available structure of rat SP-A and a computationally-docked model of SP-A-TLR4-MD2 protein complex. Together, our results support the structural adaptability of SPA4 peptide for binding to TLR4.

Dock-family exchange factors in cell migration and disease

Dock family proteins are evolutionary conserved exchange factors for the Rho GTPases Rac and Cdc42. There are 11 Dock proteins in mammals, named Dock1 (or Dock180) to Dock11 that play different cellular functions. In particular, Dock proteins regulate actin cytoskeleton, cell adhesion and migration. Not surprisingly, members of the Dock family have been involved in various pathologies, including cancer and defects in the central nervous and immune systems. This review proposes an update of the recent findings regarding the function of Dock proteins, focusing on their role in the control of cell migration and invasion and the consequences in human diseases.

Modulation of angiogenesis by thyroid hormone and hormone analogues: implications for cancer management

Acting via a cell surface receptor on integrin αvβ3, thyroid hormone is pro-angiogenic. Nongenomic mechanisms of actions of the hormone and hormone analogues at αvβ3 include modulation of activities of multiple vascular growth factor receptors and their ligands (vascular endothelial growth factor, basic fibroblast growth factor, platelet-derived growth factor, epidermal growth factor), as well as of angiogenic chemokines (CX3 family). Thyroid hormone also may increase activity of small molecules that support neovascularization (bradykinin, angiotensin II) and stimulate endothelial cell motility. Therapeutic angio-inhibition in the setting of cancer may be opposed by endogenous thyroid hormone, particularly when a single vascular growth factor is the treatment target. This may be a particular issue in management of aggressive or recurrent tumors. It is desirable to have access to chemotherapies that affect multiple steps in angiogenesis and to examine as alternatives in aggressive cancers the induction of subclinical hypothyroidism or use of antagonists of the αvβ3 thyroid hormone receptor that are under development.

Expression of toll-like receptors on human rectal adenocarcinoma cells

The innate immune system uses Toll-like receptors (TLR) to detect the presence of pathogen patterns thus allowing for rapid host defense responses. Stimulation of TLR results in inflammatory response and regulatory cytokine production affecting acquired immunity. The aim of the study was an evaluation of TLR2 and TLR4 expression on the surface of human colon cancer cells in primary culture with or without autologous peripheral blood mononuclear cells. Surgical specimens of colon cancer were processed to obtain cancer cells. Cancer cells separation was conducted first by mechanical tissue disintegration and than by gradient centrifugation to obtain 95 % cell confluence. By staining the isolated cells the pathologist determined them as adenocarcinoma. Colon cancer cells were then co-cultured in 24 h culture alone or together with autologous lymphocytes. Reverse-transcription polymerase chain reaction was performed for detection of TLR2 and TLR4 mRNA in colon cancer and normal colon epithelial cells using commercially available primers. Resting as well as phytohemagglutinin or lipopolysaccharide (LPS) stimulated cells were tested. Receptor proteins on cancer cells were examined by immunohistochemistry. TLR4 mRNA was detected in cancer cells. Autologous lymphocytes do not exert any effect on these receptors expression. TLR4 mRNA expression was not observed in normal colon epithelial cells. TLR2 mRNA was present on LPS stimulated cancer cells as well as on resting and stimulated lymphocytes. Expression of TLR2 and TLR4 receptor proteins on colon cancer cells were confirmed by immunohistochemistry. TLR4 may be responsible for uncontrolled tumor growth under LPS stimulation in human colon environment.

Trial Watch: Toll-like receptor agonists for cancer therapy

Toll-like receptors (TLRs) have long been known for their ability to initiate innate immune responses upon exposure to conserved microbial components such as lipopolysaccharide (LPS) and double-stranded RNA. More recently, this family of pattern recognition receptors has been attributed a critical role in the elicitation of anticancer immune responses, raising interest in the development of immunochemotherapeutic regimens based on natural or synthetic TLR agonists. In spite of such an intense wave of preclinical and clinical investigation, only three TLR agonists are currently licensed by FDA for use in cancer patients: bacillus Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis that operates as a mixed TLR2/TLR4 agonist; monophosphoryl lipid A (MPL), a derivative of Salmonella minnesota that functions as a potent agonist of TLR4; and imiquimod, a synthetic imidazoquinoline that activates TLR7. One year ago, in the August and September issues of OncoImmunology, we described the main biological features of TLRs and discussed the progress of clinical studies evaluating the safety and therapeutic potential of TLR agonists in cancer patients. Here, we summarize the latest developments in this exciting area of research, focusing on preclinical studies that have been published during the last 13 mo and clinical trials launched in the same period to investigate the antineoplastic activity of TLR agonists.

A TLR4-interacting SPA4 peptide inhibits LPS-induced lung inflammation

The interaction between surfactant protein-A (SP-A) and TLR4 is important for host defense. We have recently identified an SPA4 peptide region from the interface of SP-A-TLR4 complex. Here, we studied the involvement of the SPA4 peptide region in SP-A-TLR4 interaction using a two-hybrid system, and biological effects of SPA4 peptide in cell systems and a mouse model. HEK293 cells were transfected with plasmid DNAs encoding SP-A or a SP-A-mutant lacking SPA4 peptide region and TLR4. Luciferase activity was measured as the end-point of SP-A-TLR4 interaction. NF-κB activity was also assessed simultaneously. Next, the dendritic cells or mice were challenged with Escherichia coli-derived LPS and treated with SPA4 peptide. Endotoxic shock-like symptoms and inflammatory parameters (TNF-α, NF-κB, leukocyte influx) were assessed. Our results reveal that the SPA4 peptide region contributes to the SP-A-TLR4 interaction and inhibits the LPS-induced NF-κB activity and TNF-α. We also observed that the SPA4 peptide inhibits LPS-induced expression of TNF-α, nuclear localization of NF-κB-p65 and cell influx, and alleviates the endotoxic shock-like symptoms in a mouse model. Our results suggest that the anti-inflammatory activity of the SPA4 peptide through its binding to TLR4 can be of therapeutic benefit.

Peptidoglycans promotes human leukemic THP-1 cell apoptosis and differentiation

The innate immune system coordinates the inflammatory response to pathogens. To do so, its cells must discriminate self from non-self utilizing receptors that identify molecules synthesized exclusively by microbes. Toll- like receptors have a crucial role in the detection of microbial infection in mammals and insects. In mammals, they have evolved to recognize conserved products unique to microbial metabolism. These include lipopolysaccharide (LPS), lipotechoic acids, and peptidoglycans (PGN). We show here that TLRs, including TLR2, are expressed on the THP-1 human leukemia cell line. Activation of TLR2 signaling in THP-1 by PGN induces the synthesis of various soluble factors and proteins including interleukin-1β, interleukin-8 and TNF-α and apoptosis of THP-1 with PGN dose and time dependence. Moreover , in this study we show that PGN induces apoptosis of THP-1 cells in a TNF-α-dependent manner. These findings indicate that TLR2 signaling results in a cascade leading to tumor apoptosis and differentiation, which may suggest new clinical prospects using TLR2 agonists as cytotoxic agents in certain cancers.