The apolipoprotein E-mimetic peptide COG112 inhibits NF-kappaB signaling, proinflammatory cytokine expression, and disease activity in murine models of colitis

Reduction of APOE accounts for neurobehavioral deficits in fetal alcohol spectrum disorders

A hallmark of fetal alcohol spectrum disorders (FASD) is neurobehavioral deficits that still do not have effective treatment. Here, we present that reduction of Apolipoprotein E (APOE) is critically involved in neurobehavioral deficits in FASD. We show that prenatal alcohol exposure (PAE) changes chromatin accessibility of Apoe locus, and causes reduction of APOE levels in both the brain and peripheral blood in postnatal mice. Of note, postnatal administration of an APOE receptor agonist (APOE-RA) mitigates motor learning deficits and anxiety in those mice. Several molecular and electrophysiological properties essential for learning, which are altered by PAE, are restored by APOE-RA. Our human genome-wide association study further reveals that the interaction of PAE and a single nucleotide polymorphism in the APOE enhancer which chromatin is closed by PAE in mice is associated with lower scores in the delayed matching-to-sample task in children. APOE in the plasma is also reduced in PAE children, and the reduced level is associated with their lower cognitive performance. These findings suggest that controlling the APOE level can serve as an effective treatment for neurobehavioral deficits in FASD.

ApoE Mimetic Peptides to Improve the Vicious Cycle of Malnutrition and Enteric Infections by Targeting the Intestinal and Blood-Brain Barriers

Apolipoprotein E (apoE) mimetic peptides are engineered fragments of the native apoE protein’s LDL-receptor binding site that improve the outcomes following a brain injury and intestinal inflammation in a variety of models. The vicious cycle of enteric infections and malnutrition is closely related to environmental-driven enteric dysfunction early in life, and such chronic inflammatory conditions may blunt the developmental trajectories of children with worrisome and often irreversible physical and cognitive faltering. This window of time for microbiota maturation and brain plasticity is key to protecting cognitive domains, brain health, and achieving optimal/full developmental potential. This review summarizes the potential role of promising apoE mimetic peptides to improve the function of the gut-brain axis, including targeting the blood-brain barrier in children afflicted with malnutrition and enteric infections.

Intestinal Epithelial Cells Adapt to Chronic Inflammation through Partial Genetic Reprogramming

Reactive oxygen species (ROS) are considered to be the main drivers of inflammatory bowel disease. We investigated whether this permanent insult compels intestinal stem cells to develop strategies to dampen the deleterious effects of ROS. As an adverse effect, this adaptation process may increase their tolerance to oncogenic insults and facilitate their neoplastic transformation. We submitted immortalized human colonic epithelial cells to either a mimic of chronic inflammation or to a chemical peroxide, analyzed how they adapted to stress, and addressed the biological relevance of these observations in databases. We demonstrated that cells adapt to chronic-inflammation-associated oxidative stress in vitro through a partial genetic reprogramming. Through a gene set enrichment analysis, we showed that this program is recurrently active in the intestinal mucosae of Crohn's and ulcerative colitis disease patients and evolves alongside disease progression. Based on a previously reported characterization of intestinal stem and precursor cells using tracing experiments, we lastly confirmed the activation of the program in intestinal precursor cells during murine colorectal cancer development. This adaptive process is thus likely to play a role in the progression of Crohn's and ulcerative disease, and potentially in the initiation of colorectal cancer.

Protective Role of the Toll-Like Receptor 5 Agonist KMRC011 against Murine Colitis Induced by Citrobacter rodentium and Dextran Sulfate Sodium

This study aimed to identify the therapeutic ability of a novel toll-like receptor (TLR) 5 agonist, KMRC011, on ulcerative colitis induced by Citrobacter rodentium and dextran sulfate sodium in a C57BL/6N mouse model. Ulcerative colitis was induced in the mice by the oral administration of 1% dextran sulfate sodium in sterile drinking water for seven days ad libitum, followed by C. rodentium infection on the seventh day by intra-gastric administration (DSS-CT group). KMRC011 was administered intramuscularly at both 24 h and 15 min before (Treatment 1 group), and at both 15 min and 24 h after (Treatment 2 group) the C. rodentium infection. The length of the large intestine and histopathological counts were significantly greater and mucosal thickness was significantly thinner in the Treatment 1 group compared to the DSS-CT and Treatment 2 groups. Il-6 and Il-10 mRNA expression levels were upregulated, while Ifn-γ and Tnf-α mRNA expression levels were significantly downregulated in the Treatment 1 group, compared to the DSS-CT group. NF-κB p65 expression level was elevated due to ulcerative colitis in the DSS-CT group, but was significantly downregulated in the Treatment 1 group. Overall, KMRC011 showed protective effects against murine colitis by inhibiting NF-κB signaling.

Cyclic Peptides for the Treatment of Cancers: A Review

Cyclic peptides have been widely reported to have therapeutic abilities in the treatment of cancer. This has been proven through in vitro and in vivo studies against breast, lung, liver, colon, and prostate cancers, among others. The multitude of data available in the literature supports the potential of cyclic peptides as anticancer agents. This review summarizes the findings from previously reported studies and discusses the different cyclic peptide compounds, the sources, and their modes of action as anticancer agents. The prospects and future of cyclic peptides will also be described to give an overview on the direction of cyclic peptide development for clinical applications.

CCL11 exacerbates colitis and inflammation-associated colon tumorigenesis

CCL11, also known as eotaxin-1, is described as an eosinophil chemoattractant, which has been implicated in allergic and Th2 inflammatory diseases. We have reported that CCL11 is significantly increased in the serum of inflammatory bowel disease (IBD) patients, colonic eosinophils are increased and correlate with tissue CCL11 levels in ulcerative colitis patients, and CCL11 is increased in dextran sulfate sodium (DSS)-induced murine colitis. Here, we show that CCL11 is involved in the pathogenesis of DSS-induced colitis and in colon tumorigenesis in the azoxymethane (AOM)-DSS model of colitis-associated carcinogenesis (CAC). Ccl11^-/- mice exposed to DSS then allowed to recover had significantly less body weight loss and a decrease in histologic injury versus wild-type (WT) mice. In the AOM-DSS model, Ccl11^-/- mice exhibited decreased colonic tumor number and burden, histologic injury, and colonic eosinophil infiltration versus WT mice. Ccl11 is expressed by both colonic epithelial and lamina propria immune cells. Studies in bone marrow chimera mice revealed that hematopoietic- and epithelial-cell-derived CCL11 were both important for tumorigenesis in the AOM-DSS model. These findings indicate that CCL11 is important in the regulation of colitis and associated carcinogenesis and thus anti-CCL11 antibodies may be useful for treatment and cancer chemoprevention in IBD.

Effect of electroacupuncture on inhibition of inflammatory response and oxidative stress through activating ApoE and Nrf2 in a mouse model of spinal cord injury

INTRODUCTION

Electroacupuncture protects neurons and myelinated axons after spinal cord injury by mitigating the inflammatory response and oxidative stress, but how it exerts these effects is unclear.

METHODS AND RESULTS

Spinal cord injury was induced in C57BL/6 wild-type and apolipoprotein E (ApoE) knockout (ApoE^-/- ) mice, followed by electroacupuncture or ApoE mimetic peptide COG112 treatment. Mice with spinal cord injury suffered loss of myelinated axons and hindlimb motor function through the detections of Basso mouse scale, histology, and transmission electron microscopy; electroacupuncture partially reversed these effects in wild-type mice but not in ApoE^-/- mice. Combining exogenous ApoE administration with electroacupuncture significantly mitigated the effects of spinal cord injury in both mouse strains, and these effects were associated with up-regulation of anti-inflammatory cytokines and down-regulation of pro-inflammatory cytokines which were detected by quantitative reverse transcription-polymerase chain reaction. Combination treatment also reduced oxidative stress by up-regulating ApoE and Nrf2/HO-1 signaling pathway through the detections of immunofluorescence and western blot analysis.

CONCLUSIONS

These results suggest that electroacupuncture protects neurons and myelinated axons following spinal cord injury through an ApoE-dependent mechanism.

Immunoinflammatory role of apolipoprotein E4 in malnutrition and enteric infections and the increased risk for chronic diseases under adverse environments

Apolipoprotein E plays a crucial role in cholesterol metabolism. The immunomodulatory functions of the human polymorphic APOE gene have gained particular interest because APOE4, a well-recognized risk factor for late-onset Alzheimer's disease, has also been recently linked to increased risk of COVID-19 infection severity in a large UK biobank study. Although much is known about apoE functions in the nervous system, much less is known about APOE polymorphism effects on malnutrition and enteric infections and the consequences for later development in underprivileged environments. In this review, recent findings are summarized of apoE's effects on intestinal function in health and disease and the role of APOE4 in protecting against infection and malnutrition in children living in unfavorable settings, where poor sanitation and hygiene prevail, is highlighted. The potential impact of APOE4 on later development also is discussed and gaps in knowledge are identified that need to be addressed to protect children's development under adverse environments.

Atherosclerosis and Inflammatory Bowel Disease-Shared Pathogenesis and Implications for Treatment

Atherosclerosis and inflammatory bowel disease (IBD) are often regarded as 2 distinct entities. The commonest manifestation of atherosclerosis is ischemic heart disease (IHD), and an association between IHD and IBD has been reported. Atherosclerosis and IBD share common pathophysiological mechanisms in terms of their genetics, immunology, and contributing environmental factors. Factors associated with atherosclerosis are implicated in the development of IBD and vice versa. Therefore, treatments targeting the common pathophysiology pathways may be effective in both conditions. The current review considers the pathophysiological pathways that are shared between the 2 conditions and discusses the implications for treatment and research.

Oleoylethanolamide Ameliorates Dextran Sulfate Sodium-Induced Colitis in Rats

Oleoylethanolamide (OEA) is an endogenous fatty acid ethanolamide known for its anti-inflammatory effects and its influence on gut microbiota composition; however, the effects of OEA in inflammatory bowel disease (IBD) remain unknown. During in vitro experiments, OEA downregulated the expression of tumor necrosis factor (TNF)-α and reduced phosphorylation of inhibitor of kappa (Iκ) Bα induced by lipopolysaccharide in human embryonic kidney cells. Moreover, OEA downregulated the expression of interleukin (IL)-8 and IL-1β and inhibited the phosphorylation of IκBα and p65 induced by TNF-α in human enterocytes (Caco-2). The effect of OEA in reducing the expression of IL-8 was blocked by the peroxisome proliferator-activated receptor (PPAR)-α antagonist. During in vivo experiments on rats, colitis was induced by the oral administration of 8% dextran sulfate sodium from day 0 through day 5, and OEA (20 mg/kg) was intraperitoneally injected once a day from day 0 for 6 days. OEA administration significantly ameliorated the reduction in body weight, the increase in disease activity index score, and the shortening of colon length. In rectums, OEA administration reduced the infiltration of macrophages and neutrophils and tended to reduce the histological score and the expression of inflammatory cytokines. Administration of OEA produced significant improvement in a colitis model, possibly by inhibiting the nuclear factor kappa B signaling pathway through PPAR-α receptors. OEA could be a potential new treatment for IBD.

Interventions of natural and synthetic agents in inflammatory bowel disease, modulation of nitric oxide pathways

Inflammatory bowel disease (IBD) refers to a group of disorders characterized by chronic inflammation of the gastrointestinal (GI) tract. The elevated levels of nitric oxide (NO) in serum and affected tissues; mainly synthesized by the inducible nitric oxide synthase (iNOS) enzyme; can exacerbate GI inflammation and is one of the major biomarkers of GI inflammation. Various natural and synthetic agents are able to ameliorate GI inflammation and decrease iNOS expression to the extent comparable with some IBD drugs. Thereby, the purpose of this study was to gather a list of natural or synthetic mediators capable of modulating IBD through the NO pathway. Electronic databases including Google Scholar and PubMed were searched from 1980 to May 2018. We found that polyphenols and particularly flavonoids are able to markedly attenuate NO production and iNOS expression through the nuclear factor κB (NF-κB) and JAK/STAT signaling pathways. Prebiotics and probiotics can also alter the GI microbiota and reduce NO expression in IBD models through a broad array of mechanisms. A number of synthetic molecules have been found to suppress NO expression either dependent on the NF-κB signaling pathway (i.e., dexamethasone, pioglitazone, tropisetron) or independent from this pathway (i.e., nicotine, prednisolone, celecoxib, β-adrenoceptor antagonists). Co-administration of natural and synthetic agents can affect the tissue level of NO and may improve IBD symptoms mainly by modulating the Toll like receptor-4 and NF-κB signaling pathways.

Cationic Arginine-Rich Peptides (CARPs): A Novel Class of Neuroprotective Agents With a Multimodal Mechanism of Action

There are virtually no clinically available neuroprotective drugs for the treatment of acute and chronic neurological disorders, hence there is an urgent need for the development of new neuroprotective molecules. Cationic arginine-rich peptides (CARPs) are an expanding and relatively novel class of compounds, which possess intrinsic neuroprotective properties. Intriguingly, CARPs possess a combination of biological properties unprecedented for a neuroprotective agent including the ability to traverse cell membranes and enter the CNS, antagonize calcium influx, target mitochondria, stabilize proteins, inhibit proteolytic enzymes, induce pro-survival signaling, scavenge toxic molecules, and reduce oxidative stress as well as, having a range of anti-inflammatory, analgesic, anti-microbial, and anti-cancer actions. CARPs have also been used as carrier molecules for the delivery of other putative neuroprotective agents across the blood-brain barrier and blood-spinal cord barrier. However, there is increasing evidence that the neuroprotective efficacy of many, if not all these other agents delivered using a cationic arginine-rich cell-penetrating peptide (CCPPs) carrier (e.g., TAT) may actually be mediated largely by the properties of the carrier molecule, with overall efficacy further enhanced according to the amino acid composition of the cargo peptide, in particular its arginine content. Therefore, in reviewing the neuroprotective mechanisms of action of CARPs we also consider studies using CCPPs fused to a putative neuroprotective peptide. We review the history of CARPs in neuroprotection and discuss in detail the intrinsic biological properties that may contribute to their cytoprotective effects and their usefulness as a broad-acting class of neuroprotective drugs.

Dietary Arginine Regulates Severity of Experimental Colitis and Affects the Colonic Microbiome

There is great interest in safe and effective alternative therapies that could benefit patients with inflammatory bowel diseases (IBD). L-arginine (Arg) is a semi-essential amino acid with a variety of physiological effects. In this context, our aim was to investigate the role of dietary Arg in experimental colitis. We used two models of colitis in C57BL/6 mice, the dextran sulfate sodium (DSS) model of injury and repair, and Citrobacter rodentium infection. Animals were given diets containing (1) no Arg (Arg0), 6.4 g/kg (ArgNL), or 24.6 g/kg Arg (ArgHIGH); or (2) the amino acids downstream of Arg: 28 g/kg L-ornithine (OrnHIGH) or 72 g/kg L-proline (ProHIGH). Mice with DSS colitis receiving the ArgHIGH diet had increased levels of Arg, Orn, and Pro in the colon and improved body weight loss, colon length shortening, and histological injury compared to ArgNL and Arg0 diets. Histology was improved in the ArgNL vs. Arg0 group. OrnHIGH or ProHIGH diets did not provide protection. Reduction in colitis with ArgHIGH diet also occurred in C. rodentium-infected mice. Diversity of the intestinal microbiota was significantly enhanced in mice on the ArgHIGH diet compared to the ArgNL or Arg0 diets, with increased abundance of Bacteroidetes and decreased Verrucomicrobia. In conclusion, dietary supplementation of Arg is protective in colitis models. This may occur by restoring overall microbial diversity and Bacteroidetes prevalence. Our data provide a rationale for Arg as an adjunctive therapy in IBD.

Loss of solute carrier family 7 member 2 exacerbates inflammation-associated colon tumorigenesis

Solute carrier family 7 member 2 (SLC7A2, also known as CAT2) is an inducible transporter of the semi-essential amino acid L-arginine (L-Arg), which has been implicated in wound repair. We have reported that both SLC7A2 expression and L-Arg availability are decreased in colonic tissues from inflammatory bowel disease patients and that mice lacking Slc7a2 exhibit a more severe disease course when exposed to dextran sulfate sodium (DSS) compared to wild-type (WT) mice. Here, we present evidence that SLC7A2 plays a role in modulating colon tumorigenesis in the azoxymethane(AOM)-DSS model of colitis-associated carcinogenesis (CAC). SLC7A2 was localized predominantly to colonic epithelial cells in WT mice. Utilizing the AOM-DSS model, Slc7a2^–/– mice had significantly increased tumor number, burden, and risk of high-grade dysplasia versus WT mice. Tumors from Slc7a2^–/– mice exhibited significantly increased levels of the proinflammatory cytokines/chemokines IL-1β, CXCL1, CXCL5, IL-3, CXCL2, CCL3, and CCL4, but decreased levels of IL-4, CXCL9, and CXCL10 compared to tumors from WT mice. This was accompanied by a shift toward pro-tumorigenic M2 macrophage activation in Slc7a2-deficient mice, as marked by increased colonic CD11b⁺F4/80⁺ARG1⁺ cells with no alteration in CD11b⁺F4/80⁺NOS2⁺ cells by flow cytometry and immunofluorescence microscopy. The shift toward M2 macrophage activation was confirmed in bone marrow-derived macrophages from Slc7a2^–/– mice. In bone marrow chimeras between Slc7a2^–/– and WT mice, the recipient genotype drove the CAC phenotype, suggesting the importance of epithelial SLC7A2 in abrogating neoplastic risk. These data reveal that SLC7A2 has a significant role in the protection from CAC in the setting of chronic colitis, and suggest that the decreased SLC7A2 in inflammatory bowel disease (IBD) may contribute to CAC risk. Strategies to enhance L-Arg availability by supplementing L-Arg and/or increasing L-Arg uptake could represent a therapeutic approach in IBD to reduce the substantial long-term risk of colorectal carcinoma.

BVES is required for maintenance of colonic epithelial integrity in experimental colitis by modifying intestinal permeability

Blood vessel epicardial substance (BVES), or POPDC1, is a tight junction-associated transmembrane protein that modulates epithelial-to-mesenchymal transition (EMT) via junctional signaling pathways. There have been no in vivo studies investigating the role of BVES in colitis. We hypothesized that BVES is critical for maintaining colonic epithelial integrity. At baseline, Bves-/- mouse colons demonstrate increased crypt height, elevated proliferation, decreased apoptosis, altered intestinal lineage allocation, and dysregulation of tight junctions with functional deficits in permeability and altered intestinal immunity. Bves-/- mice inoculated with Citrobacter rodentium had greater colonic injury, increased colonic and mesenteric lymph node bacterial colonization, and altered immune responses after infection. We propose that increased bacterial colonization and translocation result in amplified immune responses and worsened injury. Similarly, dextran sodium sulfate (DSS) treatment resulted in greater histologic injury in Bves-/- mice. Two different human cell lines (Caco2 and HEK293Ts) co-cultured with enteropathogenic E. coli showed increased attaching/effacing lesions in the absence of BVES. Finally, BVES mRNA levels were reduced in human ulcerative colitis (UC) biopsy specimens. Collectively, these studies suggest that BVES plays a protective role both in ulcerative and infectious colitis and identify BVES as a critical protector of colonic mucosal integrity.

Major Bioactive Compounds in Essential Oils Extracted From the Rhizomes of Zingiber zerumbet (L) Smith: A Mini-Review on the Anti-allergic and Immunomodulatory Properties

Zingiber zerumbet (L) Smith is part of the Zingiberaceae family, one of the largest families of the plant kingdom. Z. zerumbet is a perennial, aromatic and tuberose plant that grows in humid locations where its center of distribution is located in the South-East Asia region. This plant has been traditionally used in foods and beverages and for ornamental purposes. Although many studies have reported on the biomedical applications of Z. zerumbet, the anti-allergic effects of Z. zerumbet and its major bioactive compounds have not yet been summarized in detail. Many major metabolites that have been reported to contain anti-allergic properties are terpene compounds which can be found in the essential oil extracted from the rhizomes of Z. zerumbet, such as zerumbone, limonene, and humulene. The rhizome is among the part of Z. zerumbet that has been widely used for many studies due to its exceptional biomedical applications. Most of these studies have shown that the essential oil, which can be obtained through hydro-distillation of the rhizomes from Z. zerumbet, is enriched with various active metabolites. Therefore, this mini-review provides an overview of the main aspects related to the anti-allergic and immunomodulatory properties of the major bioactive compounds found in the essential oils extracted from the rhizomes of Z. zerumbet, with the aim of demonstrating the importance of essential oil extracted from the rhizomes of Z. zerumbet and its bioactive compounds in the treatment of allergy and allergy-related diseases, in addition to other widely reported and extensively studied biomedical applications.

Distinct Immunomodulatory Effects of Spermine Oxidase in Colitis Induced by Epithelial Injury or Infection

Polyamines have been implicated in numerous biological processes, including inflammation and carcinogenesis. Homeostatic regulation leads to interconversion of the polyamines putrescine and the downstream metabolites spermidine and spermine. The enzyme spermine oxidase (SMOX), which back-converts spermine to spermidine, contributes to regulation of polyamine levels, but can also have other effects. We have implicated SMOX in gastric inflammation and carcinogenesis due to infection by the pathogen Helicobacter pylori. In addition, we reported that SMOX can be upregulated in humans with inflammatory bowel disease. Herein, we utilized Smox-deficient mice to examine the role of SMOX in two murine colitis models, Citrobacter rodentium infection and dextran sulfate sodium (DSS)-induced epithelial injury. In C. rodentium-infected wild-type (WT) mice, there were marked increases in colon weight/length and histologic injury, with mucosal hyperplasia and inflammatory cell infiltration; these changes were ameliorated in Smox-/- mice. In contrast, with DSS, Smox-/- mice exhibited substantial mortality, and increased body weight loss, colon weight/length, and histologic damage. In C. rodentium-infected WT mice, there were increased colonic levels of the chemokines CCL2, CCL3, CCL4, CXCL1, CXCL2, and CXCL10, and the cytokines IL-6, TNF-α, CSF3, IFN-γ, and IL-17; each were downregulated in Smox-/- mice. In DSS colitis, increased levels of IL-6, CSF3, and IL-17 were further increased in Smox-/- mice. In both models, putrescine and spermidine were increased in WT mice; in Smox-/- mice, the main effect was decreased spermidine and spermidine/spermine ratio. With C. rodentium, polyamine levels correlated with histologic injury, while with DSS, spermidine was inversely correlated with injury. Our studies indicate that SMOX has immunomodulatory effects in experimental colitis via polyamine flux. Thus, SMOX contributes to the immunopathogenesis of C. rodentium infection, but is protective in DSS colitis, indicating the divergent effects of spermidine.

A comprehensive and perspective view of oncoprotein SET in cancer

SET is a multifunctional oncoprotein which is ubiquitously expressed in all kinds of cells. The SET protein participates in many cellular processes including cell cycle, cell migration, apoptosis, transcription, and DNA repair. Accumulating evidence demonstrates that the expression and activity of SET correlate with cancer occurrence, metastasis, and prognosis. Therefore, the SET protein is regarded as a potential target for cancer therapy and several inhibitors are being developed for clinical use. Herein, we comprehensively review the physiological and pathological functions of SET as well as its structure-function relationship. Additionally, the regulatory mechanisms of SET at both transcriptional and posttranslational levels are also discussed.

Potential implications of Apolipoprotein E in early brain injury after experimental subarachnoid hemorrhage: Involvement in the modulation of blood-brain barrier integrity

Apolipoprotein E (Apoe) genetic polymorphisms have been implicated in the long term outcome of subarachnoid haemorrhage (SAH), but little is known about the effect of Apoe on the early brain injury (EBI) after SAH. This study investigated the potential role of APOE in EBI post-SAH. Multiple techniques were used to determine the early BBB disruption in EBI post-SAH in a murine model using wild-type (WT) and Apoe^−/− (KO) mice. Progressive BBB disruption (Evans blue extravasation and T2 hyperintensity in magnetic resonance imaging) was observed before the peak of endogenous APOE expression elevation at 48h after SAH. Moreover, Apoe^−/− mice exhibited more severe BBB disruption charcteristics after SAH than WT mice, including higher levels of Evans blue and IgG extravasation, T2 hyperintensity in magnetic resonance imaging, tight junction proteins degradation and endothelial cells death. Mechanistically, we found that APOE restores the BBB integrity in the acute stage after SAH via the cyclophilin A (CypA)-NF-κB-proinflammatory cytokines-MMP-9 signalling pathway. Consequently, although early BBB disruption causes neurological dysfunctions after SAH, we capture a different aspect of the effects of APOE on EBI after SAH that previous studies had overlooked and open up the idea of BBB disruption as a target of APOE-based therapy for EBI amelioration research in the future.

Ornithine decarboxylase regulates M1 macrophage activation and mucosal inflammation via histone modifications

Macrophage activation is a critical step in host responses during bacterial infections. Ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine metabolism, has been well studied in epithelial cells and is known to have essential roles in many different cellular functions. However, its role in regulating macrophage function during bacterial infections is not well characterized. We demonstrate that macrophage-derived ODC is a critical regulator of M1 macrophage activation during both Helicobacter pylori and Citrobacter rodentium infection. Myeloid-specific Odc deletion significantly increased gastric and colonic inflammation, respectively, and enhanced M1 activation. Add-back of putrescine, the product of ODC, reversed the increased macrophage activation, indicating that ODC and putrescine are regulators of macrophage function. Odc-deficient macrophages had increased histone 3, lysine 4 (H3K4) monomethylation, and H3K9 acetylation, accompanied by decreased H3K9 di/trimethylation both in vivo and ex vivo in primary macrophages. These alterations in chromatin structure directly resulted in up-regulated gene transcription, especially M1 gene expression. Thus, ODC in macrophages tempers antimicrobial, M1 macrophage responses during bacterial infections through histone modifications and altered euchromatin formation, leading to the persistence and pathogenesis of these organisms.

The L-Arginine Transporter Solute Carrier Family 7 Member 2 Mediates the Immunopathogenesis of Attaching and Effacing Bacteria

Solute carrier family 7 member 2 (SLC7A2) is an inducible transporter of the semi-essential amino acid L-arginine (L-Arg), which has been implicated in immune responses to pathogens. We assessed the role of SLC7A2 in murine infection with Citrobacter rodentium, an attaching and effacing enteric pathogen that causes colitis. Induction of SLC7A2 was upregulated in colitis tissues, and localized predominantly to colonic epithelial cells. Compared to wild-type mice, Slc7a2^–/–mice infected with C. rodentium had improved survival and decreased weight loss, colon weight, and histologic injury; this was associated with decreased colonic macrophages, dendritic cells, granulocytes, and Th1 and Th17 cells. In infected Slc7a2^–/–mice, there were decreased levels of the proinflammatory cytokines G-CSF, TNF-α, IL-1α, IL-1β, and the chemokines CXCL1, CCL2, CCL3, CCL4, CXCL2, and CCL5. In bone marrow chimeras, the recipient genotype drove the colitis phenotype, indicative of the importance of epithelial, rather than myeloid SLC7A2. Mice lacking Slc7a2 exhibited reduced adherence of C. rodentium to the colonic epithelium and decreased expression of Talin-1, a focal adhesion protein involved in the attachment of the bacterium. The importance of SLC7A2 and Talin-1 in the intimate attachment of C. rodentium and induction of inflammatory response was confirmed in vitro, using conditionally-immortalized young adult mouse colon (YAMC) cells with shRNA knockdown of Slc7a2 or Tln1. Inhibition of L-Arg uptake with the competitive inhibitor, L-lysine (L-Lys), also prevented attachment of C. rodentium and chemokine expression. L-Lys and siRNA knockdown confirmed the role of L-Arg and SLC7A2 in human Caco-2 cells co-cultured with enteropathogenic Escherichia coli. Overexpression of SLC7A2 in human embryonic kidney cells increased bacterial adherence and chemokine expression. Taken together, our data indicate that C. rodentium enhances its own pathogenicity by inducing the expression of SLC7A2 to favor its attachment to the epithelium and thus create its ecological niche.

Intestinal infections by attaching and effacing (A/E) bacteria widely impact human health, with major social and economic repercussions. Mucosal immunity plays a critical role in determining the outcome of these infections. The amino acid L-arginine regulates inflammatory responses to bacterial pathogens. We studied the role of the L-arginine transporter solute carrier family 7 member 2 (SLC7A2) during infection with the A/E pathogen Citrobacter rodentium. SLC7A2 is induced in colonic epithelial cells during the infection and facilitates the intimate attachment of the bacteria, thus initiating the inflammatory response of the infected mucosa. These data were confirmed in vitro using C. rodentium-infected mouse cells and human colonic epithelial cells infected with enteropathogenic Escherichia coli. Our work describes a mechanism by which A/E bacteria manipulate host response to favor their colonization, thereby positioning SLC7A2 as an unrecognized therapeutic target to limit infection with enterobacteria.

Inflammatory bowel disease: exploring gut pathophysiology for novel therapeutic targets

Ulcerative colitis and Crohn's disease are the 2 major phenotypes of inflammatory bowel disease (IBD), which are influenced by a complex interplay of immunological and genetic elements, though the precise etiology still remains unknown. With IBD developing into a globally prevailing disease, there is a need to explore new targets and a thorough understanding of the pathophysiological differences between the healthy and diseased gut could unearth new therapeutic opportunities. In this review, we provide an overview of the major aspects of IBD pathogenesis and thereafter present a comprehensive analysis of the gut pathophysiology leading to a discussion on some of the most promising targets and biologic therapies currently being explored. These include various gut proteins (CXCL-10, GATA-3, NKG2D, CD98, microRNAs), immune cells recruited to the gut (mast cells, eosinophils, toll-like receptors 2, 4), dysregulated proinflammatory cytokines (interleukin-6, -13, -18, -21), and commensal microbiota (probiotics and fecal microbiota transplantation). We also evaluate some of the emerging nonconventional therapies being explored in IBD treatment focusing on the latest developments in stem cell research, oral targeting of the gut-associated lymphoid tissue, novel anti-inflammatory signaling pathway targeting, adenosine deaminase inhibition, and the beneficial effects of antioxidant and nutraceutical therapies. In addition, we highlight the growth of biologics and their targets in IBD by providing information on the preclinical and clinical development of over 60 biopharmaceuticals representing the state of the art in ulcerative colitis and Crohn's disease drug development.

Mangiferin: A xanthonoid with multipotent anti-inflammatory potential

Over the last era, small molecules sourced from different plants have gained attention for their varied and long-term medicinal benefits. Their advantageous therapeutic effects in diverse pathological complications lead researchers to give an ever-increasing emphasis on them and discover their novel therapeutic potentials. Among these, the heat stable, xanthonoid group of organic molecules has gained special importance with distinctive regards to the bioactive molecule mangiferin due to its solubility in water. Mangiferin, a yellow polyphenol having C-glycosyl xanthone structure, is widely present in different edible sources like mango, and possesses numerous biological activities. Extensive research with this molecule shows its antioxidant, anti-inflammatory, antidiabetic, anticancer, antimicrobial, analgesic, and immunomodulatory properties. Thus, it provides protection against a wide range of physiological disorders. The C-glucosyl linkage and polyhydroxy groups in mangiferin's structure contribute essentially to its free radical-scavenging activity. Moreover, its ability in regulating various transcription factors like NF-κB, Nrf-2, etc. and modulating the expression of different proinflammatory signaling intermediates like tumor necrosis factor-α, COX-2, etc. contribute to its anti-inflammatory, anticancer, and antidiabetic potentials. In this comprehensive article, information has been provided about the sources, chemical structure, metabolism, and different biological activities of mangiferin with special emphasis on the underlying cellular signal transduction pathways. Insights into an in-depth assessment of mangiferin's anti-inflammatory therapeutic potential have also been discussed in detail. On an overall perspective, this review aims to stage mangiferin's diversified therapeutic applications and its emerging possibility as a promising drug in future based on its anti-inflammatory property. © 2016 BioFactors, 42(5):459-474, 2016.

The 5A apolipoprotein A-I (apoA-I) mimetic peptide ameliorates experimental colitis by regulating monocyte infiltration

BACKGROUND AND PURPOSE

New therapies for inflammatory bowel disease (IBD) are highly desirable. As apolipoprotein (apo)A-I mimetic peptides are beneficial in several animal models of inflammation, we hypothesized that they might be effective at inhibiting murine colitis.

EXPERIMENTAL APPROACH

Daily injections of 5A peptide, a synthetic bihelical apoA-I mimetic dissolved in PBS, or PBS alone were administered to C57BL/6 mice fed 3% (w v(-1) ) dextran sodium sulfate (DSS) in drinking water or healthy controls.

KEY RESULTS

Daily treatment with 5A peptide potently restricted DSS-induced inflammation, as indicated by improved disease activity indices and colon histology, as well as decreased intestinal tissue myeloperoxidase levels and plasma TNFα and IL-6 concentrations. Additionally, plasma levels of monocyte chemoattractant protein-1 and the monocyte expression of adhesion-mediating molecule CD11b were down-regulated, pro-inflammatory CD11b(+) /Ly6c(high) monocytes were decreased, and the number of intestinal monocytes was reduced in 5A peptide-treated animals as determined by intravital macrophage-related peptide-8/14-directed fluorescence-mediated tomography and post-mortem immunhistochemical F4/80 staining. Intravital fluorescence microscopy of colonic microvasculature demonstrated inhibitory effects of 5A peptide on leukocyte adhesion accompanied by reduced plasma levels of the soluble adhesion molecule sICAM-1. In vitro 5A peptide reduced monocyte adhesion and transmigration in TNFα-stimulated monolayers of human intestinal microvascular endothelial cells. Increased susceptibility to DSS-induced inflammation was noted in apoA-I(-/-) mice.

CONCLUSIONS AND IMPLICATIONS

The 5A peptide is effective at ameliorating murine colitis by preventing intestinal monocyte infiltration and activation. These findings point to apoA-I mimetics as a potential treatment approach for IBD.

MicroRNA-16 is putatively involved in the NF-κB pathway regulation in ulcerative colitis through adenosine A2a receptor (A2aAR) mRNA targeting

MicroRNAs (miRNAs) act as important post-transcriptional regulators of gene expression by targeting the 3′-untranslated region of their target genes. Altered expression of miR-16 is reported in human ulcerative colitis (UC), but its role in the development of the disease remains unclear. Adenosine through adenosine A2a receptor (A2aAR) could inhibit nuclear factor-kappaB (NF-κB) signaling pathway in inflammation. Here we identified overexpression of miR-16 and down-regulation of A2aAR in the colonic mucosa of active UC patients. We demonstrated that miR-16 negatively regulated the expression of the A2aAR at the post-transcriptional level. Furthermore, transfection of miR-16 mimics promoted nuclear translocation of NF-κB p65 protein and expression of pro-inflammatory cytokines, IFN-γ and IL-8 in colonic epithelial cells. Treatment with miR-16 inhibitor could reverse these effects in cells. The A2aAR-mediated effects of miR-16 on the activation of the NF-κB signaling pathway were confirmed by the A2aAR knockdown assay. Our results suggest that miR-16 regulated the immune and inflammatory responses, at least in part, by suppressing the expression of the A2aAR to control the activation of the NF-κB signaling pathway.

L-Arginine Availability and Metabolism Is Altered in Ulcerative Colitis

BACKGROUND

L-arginine (L-Arg) is the substrate for both inducible nitric oxide (NO) synthase (NOS2) and arginase (ARG) enzymes. L-Arg is actively transported into cells by means of cationic amino acid transporter (SLC7) proteins. We have linked L-Arg and arginase 1 activity to epithelial restitution. Our aim was to determine if L-Arg, related amino acids, and metabolic enzymes are altered in ulcerative colitis (UC).

METHODS

Serum and colonic tissues were prospectively collected from 38 control subjects and 137 UC patients. Dietary intake, histologic injury, and clinical disease activity were assessed. Amino acid levels were measured by high-performance liquid chromatography. Messenger RNA (mRNA) levels were measured by real-time PCR. Colon tissue samples from 12 Crohn's disease patients were obtained for comparison.

RESULTS

Dietary intake of arginine and serum L-Arg levels were not different in UC patients versus control subjects. In active UC, tissue L-Arg was decreased, whereas L-citrulline (L-Cit) and the L-Cit/L-Arg ratio were increased. This pattern was also seen when paired involved (left) versus uninvolved (right) colon tissues in UC were assessed. In active UC, SLC7A2 and ARG1 mRNA levels were decreased, whereas ARG2 and NOS2 were increased. Similar alterations in mRNA expression occurred in tissues from Crohn's disease patients. In involved UC, SLC7A2 and ARG1 mRNA levels were decreased, and NOS2 and ARG2 increased, when compared with uninvolved tissues.

CONCLUSIONS

Patients with UC exhibit diminished tissue L-Arg, likely attributable to decreased cellular uptake and increased consumption by NOS2. These findings combined with decreased ARG1 expression indicate a pattern of dysregulated L-Arg availability and metabolism in UC.

The Central Role of Proprotein Convertase Subtilisin/Kexin Type 9 in Septic Pathogen Lipid Transport and Clearance

Microbial cell walls contain pathogenic lipids, including LPS in gram-negative bacteria, lipoteichoic acid in gram-positive bacteria, and phospholipomannan in fungi. These pathogen lipids are major ligands for innate immune receptors and figure prominently in triggering the septic inflammatory response. Alternatively, pathogen lipids can be cleared and inactivated, thus limiting the inflammatory response. Accordingly, biological mechanisms for sequestering and clearing pathogen lipids from the circulation have evolved. Pathogen lipids released into the circulation are initially bound by transfer proteins, notably LPS binding protein and phospholipid transfer protein, and incorporated into high-density lipoprotein particles. Next, LPS binding protein, phospholipid transfer protein, and other transfer proteins transfer these lipids to ApoB-containing lipoproteins, including low-density (LDL) and very-low-density lipoproteins and chylomicrons. Pathogen lipids within these lipoproteins and their remnants are then cleared from the circulation by the liver. Hepatic clearance involves the LDL receptor (LDLR) and possibly other receptors. Once absorbed by the liver, these lipids are then excreted in the bile. Recent evidence suggests pathogen lipid clearance can be modulated. Importantly, reduced proprotein convertase subtilisin/kexin type 9 activity increases recycling of the LDLR and thereby increases LDLR on the surface of hepatocytes, which increases clearance by the liver of pathogen lipids transported in LDL. Increased pathogen lipid clearance, which can be achieved by inhibiting proprotein convertase subtilisin/kexin type 9, may decrease the systemic inflammatory response to sepsis and improve clinical outcomes.

Inhibition of Interleukin-10 Signaling Induces Microbiota-dependent Chronic Colitis in Apolipoprotein E Deficient Mice

BACKGROUND

Apolipoprotein E (ApoE) mediates potent antiinflammatory and immunomodulatory properties in addition to its roles in regulating cholesterol transport and metabolism. However, its role in the intestine, specifically during inflammation, is largely unknown.

METHODS

Mice (C57BL/6 or ApoE-deficient [ApoE-KO] mice) were administered either single or 4 injections (weekly) of anti-interleukin (IL)-10 receptor monoclonal antibody (1.0 mg/mouse; intraperitoneally) and euthanized 1 week after the last injection. 16S rRNA sequencing was performed in fecal samples to analyze the gut bacterial load and its composition. Microbiota was ablated by administration of broad-spectrum antibiotics in drinking water. IL-10KO mice were cohoused with ApoE-KO mice or their wild-type littermates to monitor the colitogenic potential of gut microbiota harbored in ApoE-KO mice.

RESULTS

ApoE-KO mice developed severe colitis upon neutralization of IL-10 signaling as assessed by every parameter analyzed. 16S rRNA sequencing revealed that the ApoE-KO mice display elevated and altered gut microbiota that were accompanied with impaired production of intestinal antimicrobial peptides. Interestingly, microbiota ablation ameliorates colitis development in ApoE-KO mice. Exacerbated and accelerated colitis was observed in IL-10KO mice when cohoused with ApoE-KO mice.

CONCLUSIONS

Our study highlights a novel interplay between ApoE and IL-10 in maintaining gut homeostasis and that such crosstalk may play a critical role in the pathogenesis of inflammatory bowel disease. Gut sterilization and the cohousing experiment suggest that microbiota play a pivotal role in the development of inflammatory bowel disease in mice lacking ApoE.

Human Amnion-Derived Mesenchymal Stem Cell Transplantation Ameliorates Dextran Sulfate Sodium-Induced Severe Colitis in Rats

Mesenchymal stem cells (MSCs) are a valuable cell source in regenerative medicine. Recently, several studies have shown that MSCs can be easily isolated from human amnion. In this study, we investigated the therapeutic effect of human amnion-derived MSCs (AMSCs) in rats with severe colitis. Colitis was induced by the administration of 8% dextran sulfate sodium (DSS) from day 0 to day 5, and AMSCs (1 × 106 cells) were transplanted intravenously on day 1. Rats were sacrificed on day 5, and the colon length and histological colitis score were evaluated. The extent of inflammation was evaluated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry. The effect of AMSCs on the inflammatory signals was investigated in vitro. AMSC transplantation significantly ameliorated the disease activity index score, weight loss, colon shortening, and the histological colitis score. mRNA expression levels of proinflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and migration inhibitory factor (MIF) were significantly decreased in the rectums of AMSC-treated rats. In addition, the infiltration of monocytes/macrophages was significantly decreased in AMSC-treated rats. In vitro experiments demonstrated that activation of proinflammatory signals induced by TNF-α or lipopolysaccharide (LPS) in immortalized murine macrophage cells (RAW264.7) was significantly attenuated by coculturing with AMSCs or by culturing with a conditioned medium obtained from AMSCs. Although the phosphorylation of IκB induced by TNF-α or LPS was not inhibited by the conditioned medium, nuclear translocation of NF-κB was significantly inhibited by the conditioned medium. Taken together, AMSC transplantation provided significant improvement in rats with severe colitis, possibly through the inhibition of monocyte/macrophage activity and through inhibition of NF-κB activation. AMSCs could be considered as a new cell source for the treatment of severe colitis.

Preventive and therapeutic effects of blueberry (Vaccinium corymbosum) extract against DSS-induced ulcerative colitis by regulation of antioxidant and inflammatory mediators

Inflammatory bowel disease (IBD) is an inflammatory disorder caused by hyperactivation of effector immune cells that produce high levels of proinflammatory cytokines. The aims of our study were to determine whether orally administered blueberry extract (BE) could attenuate or prevent the development of experimental colitis in mice and to elucidate the mechanism of action. Female Balb/C mice (n=7) were randomized into groups differing in treatment conditions (prevention and treatment) and dose of BE (50 mg/kg body weight). Acute ulcerative colitis was induced by oral administration of 3% dextran sodium sulfate for 7 days in drinking water. Colonic mucosal injury was assessed by clinical, macroscopic, biochemical and histopathological examinations. BE significantly decreased disease activity index and improved the macroscopic and histological score of colons when compared to the colitis group (P<.05). BE markedly attenuated myeloperoxidase accumulation (colitis group 54.97±2.78 nmol/mg, treatment group 30.78±1.33 nmol/mg) and malondialdehyde in colon and prostaglandin E2 level in serum while increasing the levels of superoxide dismutase and catalase (colitis group 11.94±1.16 U/ml, BE treatment group 16.49±0.39 U/ml) compared with the colitis group (P<.05). mRNA levels of the cyclooxygenase (COX)-2, interferon-γ, interleukin (IL)-1β and inducible nitric oxide synthase cytokines were determined by reverse transcriptase polymerase chain reaction. Immunohistochemical analysis showed that BE attenuates the expression of COX-2 and IL-1β in colonic tissue. Moreover, BE reduced the nuclear translocation of nuclear transcription factor kappa B (NF-κB) by immunofluorescence analysis. Thus, the anti-inflammatory effect of BE at colorectal sites is a result of a number of mechanisms: antioxidation, down-regulation of the expression of inflammatory mediators and inhibition of the nuclear translocation of NF-κB.

Proinflammatory role of the histamine H4 receptor in dextrane sodium sulfate-induced acute colitis

Millions of people worldwide are suffering from inflammatory bowel disease (IBD), which severely affects patients' life qualities and even life expectancies. The cause of the ailment is unknown and a profound understanding of the underlying pathogenetic mechanisms is still lacking. The biogenic amine histamine is one of several inflammatory mediators, to which a pathogenetic role in IBD has been attributed. Out of the four known histamine receptors, the histamine H4 receptor (H4R) has been demonstrated to act proinflammatory in experimental models of several inflammatory diseases. In order to evaluate a potential involvement of H4R in IBD we investigated the effect of genetic or pharmacological blockade of H4R-signaling in the model of dextran sodium sulfate (DSS)-induced colitis in mice. We analysed severity and progression of clinical signs of colitis, as well as histopathologic alterations in the colons and systemic or local cytokine concentrations. Both genetic deficiency and pharmacological blockade of H4R with the selective antagonist JNJ7777120 improved clinical and histological signs of colitis and dampened the inflammatory cytokine response. Our results indicate a proinflammatory role of histamine via H4R in IBD, thus extending the current pathophysiological understanding of IBD and demonstrating the therapeutic potential of selective H4R-antagonists for patients suffering from IBD.

Active components alignment of Gegenqinlian decoction protects ulcerative colitis by attenuating inflammatory and oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Gegenqinlian Decoction (GQD) has been used as a folk remedy for gastrointestinal diseases in China over thousands of years. It has significant treatment efficacy for patients with inflammatory bowel disease (IBD). We analyzed and showed that the active components alignment of Gegenqinlian Decoction (ACAG) possesses broad pharmacological effects including analgesic, antipyretic, anti-inflammatory, antibacterial, antiviral and antidiarrhea, as well as the effect of adjusting gastrointestinal function in our preliminary experiments. However, the exact molecular mechanisms on how ACAG exerts these pharmacological effects still remain elusive. In the present study, the plausible pharmacological effects of ACAG on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis were investigated.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats with TNBS/ethanol-induced colitis were used. The colonic wet weight, macroscopic and histological colon injury, superoxide dismutase (SOD), malonyldialdehyde (MDA), and inducible nitric oxide synthase (iNOS) activity were observed. Pro-inflammation cytokines were determined by ELISA methods, semi-quantitative RT-PCR and Immuno-histochemistry.

RESULTS

We showed administration of ACAG was able to improve colitis. This was manifested by a decreased in the score of macroscopic and histological colonic injury, by lowered colonic wet weight, accompanied by significant increased of SOD activity, and decreased of MDA and iNOS activities. The treatment also significantly reduced tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) levels in colon and serum as well as the colonic mRNA levels for several inflammatory cytokines such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), macrophage inflammatory protein-2 (MIP-2), intercellular adhesion molecule-1 (ICAM-1) and toll-like receptor 2, 4 (TLR2, TLR4). In addition, we also showed that ACAG was able to inhibit the activation and translocation of transcription factors, nuclear factor kappaBp65 (NF-κBp65) in colon.

CONCLUSIONS

Our results suggest that ACAG exhibits protective effect in TNBS-induced ulcerative colitis. We postulate that this might be due to its modulation of oxidant/anti-oxidant balance, downregulation of productions, expressions of pro-inflammatory cytokines and inhibition of NF-κBp65 signal transduction pathways.

Mangiferin attenuates the symptoms of dextran sulfate sodium-induced colitis in mice via NF-κB and MAPK signaling inactivation

Inflammatory bowel disease (IBD) is a chronic and relapsing inflammatory disorder of the gastrointestinal (GI) tract, and currently no curative treatment is available. Mangiferin, a natural glucosylxanthone mainly from the fruit, leaves and stem bark of a mango tree, has a strong anti-inflammatory activity. We sought to investigate whether mangiferin attenuates inflammation in a mouse model of chemically induced IBD. Pre-administration of mangiferin significantly attenuated dextran sulfate sodium (DSS)-induced body weight loss, diarrhea, colon shortening and histological injury, which correlated with the decline in the activity of myeloperoxidase (MPO) and the level of tumor necrosis factor-α (TNF-α) in the colon. DSS-induced degradation of inhibitory κBα (IκBα) and the phosphorylation of nuclear factor-kappa B (NF-κB) p65 as well as the mRNA expression of pro-inflammatory mediators (inducible NO synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), TNF-α, interleukin-1β (IL-1β) and IL-6) in the colon were also downregulated by mangiferin treatment. Additionally, the phosphorylation/activation of DSS-induced mitogen-activated protein kinase (MAPK) proteins was also inhibited by mangiferin treatment. In accordance with the in vivo results, mangiferin exposure blocked TNF-α-stimulated nuclear translocation of NF-κB in RAW264.7 mouse macrophage cells. Transient transfection gene reporter assay performed in TNF-α-stimulated HT-29 human colorectal adenocarcinoma cells indicated that mangiferin inhibits NF-κB transcriptional activity in a dose-dependent manner. The current study clearly demonstrates a protective role for mangiferin in experimental IBD through NF-κB and MAPK signaling inhibition. Since mangiferin is a natural compound with little toxicity, the results may contribute to the effective utilization of mangiferin in the treatment of human IBD.

Reactive oxygen species-scavenging nanomedicines for the treatment of oxidative stress injuries

This Progress Report describes a development of two types of reactive oxygen species (ROS)-scavenging nanomedicines for the treatment of oxidative stress injuries, referred to as pH-sensitive redox nanoparticle (RNP(N) ) and pH-insensitive redox nanoparticle (RNP(O) ), which are prepared by self-assembling amphiphilic block copolymers possessing nitroxide radicals as a side chain of hydrophobic segment via amine and ether linkages, respectively. Due to a protonation of amino groups in hydrophobic core, RNP(N) disintegrates in low pH environments such as ischemic, inflamed, and tumor tissues, resulting in increased ROS-scavenging activity because of the exposed nitroxide radicals from the core. Utilizing pH-responsiveness of RNP(N) , it shows remarkable therapeutic effects on oxidative stress injuries such as renal and cerebral ischemia-reperfusion injuries after intravenous administration. Moreover, RNP(N) shows an enhancement of the activity of anticancer drugs by suppression of activation of transcription factors in tumor due to the ROS scavenging. On the other hand, orally administered RNP(O) has notable characteristics such as preferential accumulation in mucosa and inflamed area of gastrointestinal tract and no uptake into blood stream. Based on these characters, RNP(O) shows a remarkable therapeutic effect for the gastrointestinal inflammation without any adverse effects. Thus, ROS-scavenging nanomedicines have therapeutic efficacy in numerous oxidative stress diseases.

APOε4 is associated with enhanced in vivo innate immune responses in human subjects

BACKGROUND

The genetic determinants of the human innate immune response are poorly understood. Apolipoprotein (Apo) E, a lipid-trafficking protein that affects inflammation, has well-described wild-type (ε3) and disease-associated (ε2 and ε4) alleles, but its connection to human innate immunity is undefined.

OBJECTIVE

We sought to define the relationship of APOε4 to the human innate immune response.

METHODS

We evaluated APOε4 in several functional models of the human innate immune response, including intravenous LPS challenge in human subjects, and assessed APOε4 association to organ injury in patients with severe sepsis, a disease driven by dysregulated innate immunity.

RESULTS

Whole blood from healthy APOε3/APOε4 volunteers induced higher cytokine levels on ex vivo stimulation with Toll-like receptor (TLR) 2, TLR4, or TLR5 ligands than blood from APOε3/APOε3 patients, whereas TLR7/8 responses were similar. This was associated with increased lipid rafts in APOε3/APOε4 monocytes. By contrast, APOε3/APOε3 and APOε3/APOε4 serum neutralized LPS equivalently and supported similar LPS responses in Apoe-deficient macrophages, arguing against a differential role for secretory APOE4 protein. After intravenous LPS, APOε3/APOε4 patients had higher hyperthermia and plasma TNF-α levels and earlier plasma IL-6 than APOε3/APOε3 patients. APOE4-targeted replacement mice displayed enhanced hypothermia, plasma cytokines, and hepatic injury and altered splenic lymphocyte apoptosis after systemic LPS compared with APOE3 counterparts. In a cohort of 828 patients with severe sepsis, APOε4 was associated with increased coagulation system failure among European American patients.

CONCLUSIONS

APOε4 is a determinant of the human innate immune response to multiple TLR ligands and associates with altered patterns of organ injury in human sepsis.

Oral nanotherapeutics: effect of redox nanoparticle on microflora in mice with dextran sodium sulfate-induced colitis

BACKGROUND

Patients with ulcerative colitis (UC) exhibit overproduction of reactive oxygen species (ROS) and imbalance of colonic microflora. We previously developed a novel redox nanoparticle (RNP(O)), which effectively scavenged ROS in the inflamed mucosa of mice with dextran sodium sulfate (DSS)-induced colitis after oral administration. The objective of this study was to examine whether the orally administered RNP(O) changed the colonic microflora in healthy mice and those with colitis.

METHODS

RNP(O) was synthesized by self-assembly of an amphiphilic block copolymer that contains stable nitroxide radicals in hydrophobic side chain via ether linkage. Colitis was induced in mice by supplementing DSS in drinking water for 7 days, and RNP(O) was orally administered daily during DSS treatment. The alterations of fecal microflora during treatment of DSS and RNP(O) were investigated using microbiological assays.

RESULTS

We investigated that RNP(O) did not result in significant changes to the fecal microflora in healthy mice. Although total aerobic and anaerobic bacteria were not significantly different between experimental groups, a remarkable increase in commensal bacteria (Escherichia coli and Staphylococcus sp.) was observed in mice with DSS-induced colitis. Interestingly, orally administered RNP(O) remarkably reduced the rate of increase of these commensal bacteria in mice with colitis.

CONCLUSIONS

On the basis of the obtained results, it was confirmed that the oral administration of RNP(O) did not change any composition of bacteria in feces, which strongly suggests a protective effect of RNP(O) on healthy environments in intestinal microflora. RNP(O) may become an effective and safe medication for treatment of UC.

Activation of adenosine A3 receptor alleviates TNF-α-induced inflammation through inhibition of the NF-κB signaling pathway in human colonic epithelial cells

To investigate the expression of adenosine A3 receptor (A3AR) in human colonic epithelial cells and the effects of A3AR activation on tumor necrosis factor alpha (TNF-α-) induced inflammation in order to determine its mechanism of action in human colonic epithelial cells, human colonic epithelial cells (HT-29 cells) were treated with different concentrations of 2-Cl-IB-MECA prior to TNF-α stimulation, followed by analysis of NF-κB signaling pathway activation and downstream IL-8 and IL-1β production. A3AR mRNA and protein were expressed in HT-29 cells and not altered by changes in TNF-α or 2-Cl-IB-MECA. Pretreatment with 2-Cl-IB-MECA prior to stimulation with TNF-α attenuated NF-κB p65 nuclear translocation as p65 protein decreased in the nucleus of cells and increased in the cytoplasm, inhibited the degradation of IκB-α, and reduced phosphorylated-IκB-α level significantly, compared to TNF-α-only-treated groups. Furthermore, 2-Cl-IB-MECA significantly decreased TNF-α-stimulated IL-8 and IL-1β mRNA expression and secretion, compared to the TNF-α-only treated group. These results confirm that A3AR is expressed in human colonic epithelial cells and demonstrate that its activation has an anti-inflammatory effect, through the inhibition of NF-κB signaling pathway, which leads to inhibition of downstream IL-8 and IL-1β expression. Therefore, A3AR activation may be a potential treatment for gut inflammatory diseases such as inflammatory bowel disease.

Interleukin 6 and apolipoprotein E as predictors of acute brain dysfunction and survival in critical care patients

BACKGROUND

Delirium occurs in up to 80% of intensive care patients and is associated with poor outcomes. The biological cause of delirium remains elusive.

OBJECTIVES

To determine if delirium and recovery are associated with serum levels of interleukins and apolipoprotein E over time and with apolipoprotein E genotype.

METHODS

The sample consisted of 77 patients with no previous cognitive deficits who required mechanical ventilation for 24 to 96 hours. Daily serum samples were obtained for enzyme-linked immunosorbent assay measurements of interleukins 6, 8, and 10 and apolipoprotein E. DNA extracted from blood was analyzed for apolipoprotein E genotyping. The Confusion Assessment Method for the Intensive Care Unit was administered daily on days 2 through 9.

RESULTS

Among the 77 patients, 23% had no delirium, 46% experienced delirium, and 31% experienced coma. Additionally, 77% had delirium or coma (acute brain dysfunction), and compared with other patients, had fewer ventilator-free days (P = .03), longer stay (P = .04), higher care needs at discharge (P = .001), higher mortality (P = .02), and higher levels of interleukin 6 (P = .03), and the APOE*3/*3 apolipoprotein E genotype (P = .05). Serum levels of apolipoprotein E correlated with levels of interleukins 8 and 10. Patients with the E4 allele of apolipoprotein E had shorter duration of delirium (P = .02) and lower mortality (P = .03) than did patients without this allele.

CONCLUSIONS

Apolipoprotein E plays a complex role in illness response and recovery in critically ill patients. The relationship between apolipoprotein E genotype and brain dysfunction and survival is unclear.

High-throughput multi-analyte Luminex profiling implicates eotaxin-1 in ulcerative colitis

Accurate and high-throughput technologies are needed for identification of new therapeutic targets and for optimizing therapy in inflammatory bowel disease. Our aim was to assess multi-analyte protein-based assays of cytokines/chemokines using Luminex technology. We have reported that Luminex-based profiling was useful in assessing response to L-arginine therapy in the mouse model of dextran sulfate sodium colitis. Therefore, we studied prospectively collected samples from ulcerative colitis (UC) patients and control subjects. Serum, colon biopsies, and clinical information were obtained from subjects undergoing colonoscopy for evaluation of UC or for non-UC indications. In total, 38 normal controls and 137 UC cases completed the study. Histologic disease severity and the Mayo Disease Activity Index (DAI) were assessed. Serum and colonic tissue cytokine/chemokine profiles were measured by Luminex-based multiplex testing of 42 analytes. Only eotaxin-1 and G-CSF were increased in serum of patients with histologically active UC vs. controls. While 13 cytokines/chemokines were increased in active UC vs. controls in tissues, only eotaxin-1 was increased in all levels of active disease in both serum and tissue. In tissues, eotaxin-1 correlated with the DAI and with eosinophil counts. Increased eotaxin-1 levels were confirmed by real-time PCR. Tissue eotaxin-1 levels were also increased in experimental murine colitis induced by dextran sulfate sodium, oxazolone, or Citrobacter rodentium, but not in murine Helicobacter pylori infection. Our data implicate eotaxin-1 as an etiologic factor and therapeutic target in UC, and indicate that Luminex-based assays may be useful to assess IBD pathogenesis and to select patients for anti-cytokine/chemokine therapies.

MTG16 contributes to colonic epithelial integrity in experimental colitis

OBJECTIVE

The myeloid translocation genes (MTGs) are transcriptional corepressors with both Mtg8(-/-) and Mtgr1(-/-) mice showing developmental and/or differentiation defects in the intestine. We sought to determine the role of MTG16 in intestinal integrity.

METHODS

Baseline and stress induced colonic phenotypes were examined in Mtg16(-/-) mice. To unmask phenotypes, we treated Mtg16(-/-) mice with dextran sodium sulphate (DSS) or infected them with Citrobacter rodentium and the colons were examined for ulceration and for changes in proliferation, apoptosis and inflammation.

RESULTS

Mtg16(-/-) mice have altered immune subsets, suggesting priming towards Th1 responses. Mtg16(-/-) mice developed increased weight loss, diarrhoea, mortality and histological colitis and there were increased innate (Gr1(+), F4/80(+), CD11c(+) and MHCII(+); CD11c(+)) and Th1 adaptive (CD4) immune cells in Mtg16(-/-) colons after DSS treatment. Additionally, there was increased apoptosis and a compensatory increased proliferation in Mtg16(-/-) colons. Compared with wild-type mice, Mtg16(-/-) mice exhibited increased colonic CD4;IFN-γ cells in vehicle-treated and DSS-treated mice. Adoptive transfer of wild-type marrow into Mtg16(-/-) recipients did not rescue the Mtg16(-/-) injury phenotype. Isolated colonic epithelial cells from DSS-treated Mtg16(-/-) mice exhibited increased KC (Cxcl1) mRNA expression when compared with wild-type mice. Mtg16(-/-) mice infected with C rodentium had more severe colitis and greater bacterial colonisation. Last, MTG16 mRNA levels were reduced in human ulcerative colitis versus normal colon tissues.

CONCLUSIONS

These observations indicate that MTG16 is critical for colonocyte survival and regeneration in response to intestinal injury and provide evidence that this transcriptional corepressor regulates inflammatory recruitment in response to injury.

Deletion of cationic amino acid transporter 2 exacerbates dextran sulfate sodium colitis and leads to an IL-17-predominant T cell response

L-Arginine (L-Arg) is a semiessential amino acid that has altered availability in human ulcerative colitis (UC), a form of inflammatory bowel disease, and is beneficial in murine colitis induced by dextran sulfate sodium (DSS), a model with similarity to UC. We assessed the role of cationic amino acid transporter 2 (CAT2), the inducible transporter of L-Arg, in DSS colitis. Expression of CAT2 was upregulated in tissues from colitic mice and localized predominantly to colonic macrophages. CAT2-deficient (CAT2-/-) mice exposed to DSS exhibited worsening of survival, body weight loss, colon weight, and histological injury. These effects were associated with increased serum L-Arg and decreased tissue L-Arg uptake and inducible nitric oxide synthase protein expression. Clinical benefits of L-Arg supplementation in wild-type mice were lost in CAT2-/- mice. There was increased infiltration of macrophages, dendritic cells, granulocytes, and T cells in colitic CAT2-/- compared with wild-type mice. Cytokine profiling revealed increases in proinflammatory granulocyte colony-stimulating factor, macrophage inflammatory protein-1α, IL-15, and regulated and normal T cell-expressed and -secreted and a shift from an IFN-γ- to an IL-17-predominant T cell response, as well as an increase in IL-13, in tissues from colitic CAT2-/- mice. However, there were no increases in other T helper cell type 2 cytokines, nor was there a global increase in macrophage-derived proinflammatory cytokines. The increase in IL-17 derived from both CD4 and γδ T cells and was associated with colonic IL-6 expression. Thus CAT2 plays an important role in controlling inflammation and IL-17 activation in an injury model of colitis, and impaired L-Arg availability may contribute to UC pathogenesis.

Apolipoprotein E and its mimetic peptide suppress Th1 and Th17 responses in experimental autoimmune encephalomyelitis

Apolipoprotein E (apoE) has been detected to possess anti-inflammatory properties that can contribute to protection against experimental autoimmune encephalomyelitis (EAE). However, its impact on Th1 and Th17 responses in EAE is unclear. In this study, we induced EAE in apoE-/- mice and wild-type mice. We observed that the absence of apoE resulted in the increased proportion of Th1 and Th17 cells in the spleens and brains, as well as up-regulated expressions of proinflammatory cytokines (IL-17, IFN-γ, TNF-α, IL-12, IL-1β and IL-6) and transcription factors (RORγt and T-bet) in the CNS. ApoE-/- mice also showed the increased release of proinflammatory cytokines by macrophages in vitro. In addition, we used a mimetic peptide of apoE, which mimic the functions of apoE except for lipid transport. ApoE mimetic peptide could reverse the above negative effect in EAE. Thus, apoE can modulate Th1 and Th17 responses, likely through its inhibitory effect on the secretion of cytokines by macrophages. Our result also suggests that apoE mimetic peptide might be developed into a therapeutic agent for multiple sclerosis.

Protective effect of naringenin against experimental colitis via suppression of Toll-like receptor 4/NF-κB signalling

Naringenin, one of the most abundant flavonoids in citrus, grapefruits and tomatoes, has been used as a traditional anti-inflammatory agent for centuries. However, the molecular mechanism of naringenin in intestinal inflammation remains unknown so far. The present study investigated a molecular basis for the protective effect of naringenin in dextran sulphate sodium-induced murine colitis. Pre-administration of naringenin significantly reduced the severity of colitis and resulted in down-regulation of pro-inflammatory mediators (inducible NO synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1), cyclo-oxygenase-2 (Cox2), TNF-α and IL-6 mRNA) in the colon mucosa. The decline in the production of pro-inflammatory cytokines, specifically TNF-α and IL-6, correlated with a decrease in mucosal Toll-like receptor 4 (TLR4) mRNA and protein. Phospho-NF-κB p65 protein was significantly decreased, which correlated with a similar decrease in phospho-IκBα protein. Consistent with the in vivo results, naringenin exposure blocked lipopolysaccharide-stimulated nuclear translocation of NF-κB p65 in mouse macrophage RAW264.7 cells. In addition, in vitro NF-κB reporter assays performed on human colonic HT-29 cells exposed to naringenin demonstrated a significant inhibition of TNF-α-induced NF-κB luciferase expression. Thus, for the first time, the present study indicates that targeted inhibition of the TLR4/NF-κB signalling pathway might be an important mechanism for naringenin in abrogating experimental colitis.