Novel anti-inflammatory action of 5-aminoimidazole-4-carboxamide ribonucleoside with protective effect in dextran sulfate sodium-induced acute and chronic colitis

A novel blood-based bioassay to monitor adiponectin signaling

The diverse beneficial effects of adiponectin-receptor signaling, including its impact on the regulation of inflammatory processes in vivo, have resulted in development of adiponectin receptor agonists as a treatment for metabolic disorders. However, there are no established non-invasive bioassays for detection of adiponectin target engagement in humans or animal models. Here, we designed an assay using small amounts of blood to assess adiponectin action. Specifically, we tested effects of the small 10-amino acid peptide adiponectin receptor agonist, ALY688, in a sublethal LPS endotoxemia model in mice. LPS-induced pro-inflammatory cytokine levels in serum were significantly reduced in mice treated with ALY688, assessed via multiplex ELISA in flow cytometry. Furthermore, ALY688 alone significantly induced TGF-β release in serum 1 h after treatment and was elevated for up to 24 h. Additionally, using a flow-cytometry panel for detection of changes in circulating immune cell phenotypes, we observed a significant increase in absolute T cell counts in mice after ALY688 treatment. To assess changes in intracellular signaling effectors downstream of adiponectin, phospho-flow cytometry was conducted. There was a significant increase in phosphorylation of AMPK and p38-MAPK in mice after ALY688 treatment. We then used human donor immune cells (PBMCs) treated with ALY688 ex vivo and observed elevation of AMPK and p38-MAPK phosphorylation from baseline in response to ALY688. Together, these results indicate we can detect adiponectin action on immune cells in vivo by assessing adiponectin signaling pathway for AMPK and p38-MAPK, as well as pro-inflammatory cytokine levels. This new approach provides a blood-based bioassay for screening adiponectin action.

Manganese Enhances the Osteogenic Effect of Silicon-Hydroxyapatite Nanowires by Targeting T Lymphocyte Polarization

Biomaterials encounter considerable challenges in extensive bone defect regeneration. The amelioration of outcomes may be attainable through the orchestrated modulation of both innate and adaptive immunity. Silicon-hydroxyapatite, for instance, which solely focuses on regulating innate immunity, is inadequate for long-term bone regeneration. Herein, extra manganese (Mn)-doping is utilized for enhancing the osteogenic ability by mediating adaptive immunity. Intriguingly, Mn-doping engenders heightened recruitment of CD4+ T cells to the bone defect site, concurrently manifesting escalated T helper (Th) 2 polarization and an abatement in Th1 cell polarization. This consequential immune milieu yields a collaborative elevation of interleukin 4, secreted by Th2 cells, coupled with attenuated interferon gamma, secreted by Th1 cells. This orchestrated interplay distinctly fosters the osteogenesis of bone marrow stromal cells and effectuates consequential regeneration of the mandibular bone defect. The modulatory mechanism of Th1/Th2 balance lies primarily in the indispensable role of manganese superoxide dismutase (MnSOD) and the phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK). In conclusion, this study highlights the transformative potential of Mn-doping in amplifying the osteogenic efficacy of silicon-hydroxyapatite nanowires by regulating T cell-mediated adaptive immunity via the MnSOD/AMPK pathway, thereby creating an anti-inflammatory milieu favorable for bone regeneration.

The Role of AMPK Signaling in Ulcerative Colitis

Ulcerative colitis (UC) is a chronic non-specific inflammatory bowel disease characterized by inflammation and ulcer formation of the intestinal mucosa. Due to its high recurrence rate, prolonged course, limited curative options, and significant impact on patients' quality of life, along with a notable potential for malignant transformation, UC is designated as a refractory global health challenge by the World Health Organization (WHO). The elucidation of the pathogenesis and therapeutic strategies for UC requires further in-depth investigation. AMP-activated protein kinase (AMPK) serves as a central regulator of cellular energy metabolic homeostasis. Emerging evidence indicates that interventions involving traditional Chinese medicine (TCM) components, as well as other pharmacological measures, exert beneficial effects on the intestinal mucosal inflammation and epithelial barrier dysfunction in UC by modulating AMPK signaling, thereby influencing biological processes such as cellular autophagy, apoptosis, inflammatory responses, macrophage polarization, and NLRP3 inflammasome-mediated pyroptosis. The role of AMPK in UC is of significant importance. This manuscript provides a comprehensive overview of the mechanisms through which AMPK is involved in UC, as well as a compilation of pharmacological agents capable of activating the AMPK signaling pathway within the context of UC. The primary objective is to facilitate a deeper comprehension of the pivotal role of AMPK in UC among researchers and clinical practitioners, thereby advancing the identification of novel therapeutic targets for interventions in UC.

Novel Biomarkers for Inflammatory Bowel Disease and Colorectal Cancer: An Interplay between Metabolic Dysregulation and Excessive Inflammation

Persistent inflammation can trigger altered epigenetic, inflammatory, and bioenergetic states. Inflammatory bowel disease (IBD) is an idiopathic disease characterized by chronic inflammation of the gastrointestinal tract, with evidence of subsequent metabolic syndrome disorder. Studies have demonstrated that as many as 42% of patients with ulcerative colitis (UC) who are found to have high-grade dysplasia, either already had colorectal cancer (CRC) or develop it within a short time. The presence of low-grade dysplasia is also predictive of CRC. Many signaling pathways are shared among IBD and CRC, including cell survival, cell proliferation, angiogenesis, and inflammatory signaling pathways. Current IBD therapeutics target a small subset of molecular drivers of IBD, with many focused on the inflammatory aspect of the pathways. Thus, there is a great need to identify biomarkers of both IBD and CRC, that can be predictive of therapeutic efficacy, disease severity, and predisposition to CRC. In this study, we explored the changes in biomarkers specific for inflammatory, metabolic, and proliferative pathways, to help determine the relevance to both IBD and CRC. Our analysis demonstrated, for the first time in IBD, the loss of the tumor suppressor protein Ras associated family protein 1A (RASSF1A), via epigenetic changes, the hyperactivation of the obligate kinase of the NOD2 pathogen recognition receptor (receptor interacting protein kinase 2 [RIPK2]), the loss of activation of the metabolic kinase, AMP activated protein kinase (AMPKα1), and, lastly, the activation of the transcription factor and kinase Yes associated protein (YAP) kinase, that is involved in proliferation of cells. The expression and activation status of these four elements are mirrored in IBD, CRC, and IBD-CRC patients and, importantly, in matched blood and biopsy samples. The latter would suggest that biomarker analysis can be performed non-invasively, to understand IBD and CRC, without the need for invasive and costly endoscopic analysis. This study, for the first time, illustrates the need to understand IBD or CRC beyond an inflammatory perspective and the value of therapeutics directed to reset altered proliferative and metabolic states within the colon. The use of such therapeutics may truly drive patients into remission.

Toll-Like Receptor 4 (TLR4) and AMPK Relevance in Cardiovascular Disease

Toll-like receptors (TLRs) are essential receptors of the innate immune system, playing a significant role in cardiovascular diseases. TLR4, with the highest expression among TLRs in the heart, has been investigated extensively for its critical role in different myocardial inflammatory conditions. Studies suggest that inhibition of TLR4 signaling pathways reduces inflammatory responses and even prevents additional injuries to the already damaged myocardium. Recent research results have led to a hypothesis that there may be a relation between TLR4 expression and 5' adenosine monophosphate-activated protein kinase (AMPK) signaling in various inflammatory conditions, including cardiovascular diseases. AMPK, as a cellular energy sensor, has been reported to show anti-inflammatory effects in various models of inflammatory diseases. AMPK, in addition to its physiological acts in the heart, plays an essential role in myocardial ischemia and hypoxia by activating various energy production pathways. Herein we will discuss the role of TLR4 and AMPK in cardiovascular diseases and a possible relation between TLRs and AMPK as a novel therapeutic target. In our opinion, AMPK-related TLR modulators will find application in treating different immune-mediated inflammatory disorders, especially inflammatory cardiac diseases, and present an option that will be widely used in clinical practice in the future.

Immune translational control by CPEB4 regulates intestinal inflammation resolution and colorectal cancer development

Upon tissue injury, cytokine expression reprogramming transiently remodels the inflammatory immune microenvironment to activate repair processes and subsequently return to homeostasis. However, chronic inflammation induces permanent changes in cytokine production which exacerbate tissue damage and may even favor tumor development. Here, we address the contribution of post-transcriptional regulation, by the RNA-binding protein CPEB4, to intestinal immune homeostasis and its role in inflammatory bowel diseases (IBD) and colorectal cancer (CRC) development. We found that intestinal damage induces CPEB4 expression in adaptive and innate immune cells, which is required for the translation of cytokine mRNA(s) such as the one encoding interleukin-22. Accordingly, CPEB4 is required for the development of gut-associated lymphoid tissues and to maintain intestinal immune homeostasis, mediating repair and remodeling after acute inflammatory tissue damage and promoting the resolution of intestinal inflammation. CPEB4 is chronically overexpressed in inflammatory cells in patients with IBD and in CRC, favoring tumor development.

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CPEB4 is overexpressed in Th17 and ILC3 cells upon intestinal barrier damage

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CPEB4 is required for Il-22 mRNA translation and IL-22 expression

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CPEB4 promotes tissue repair in acute transient inflammation

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In chronic inflammation CPEB4 exacerbates intestinal pathology and promotes tumor growth

Intestinal Epithelial AMPK Deficiency Causes Delayed Colonic Epithelial Repair in DSS-Induced Colitis

Dysfunctions in the intestinal barrier, associated with an altered paracellular pathway, are commonly observed in inflammatory bowel disease (IBD). The AMP-activated protein kinase (AMPK), principally known as a cellular energy sensor, has also been shown to play a key role in the stabilization and assembly of tight junctions. Here, we aimed to investigate the contribution of intestinal epithelial AMPK to the initiation, progression and resolution of acute colitis. We also tested the hypothesis that protection mediated by metformin administration on intestinal epithelium damage required AMPK activation. A dextran sodium sulfate (DSS)-induced colitis model was used to assess disease progression in WT and intestinal epithelial cell (IEC)-specific AMPK KO mice. Barrier integrity was analyzed by measuring paracellular permeability following dextran-4kDa gavage and pro-inflammatory cytokines and tight junction protein expression. The deletion of intestinal epithelial AMPK delayed intestinal injury repair after DSS exposure and was associated with a slower re-epithelization of the intestinal mucosa coupled with severe ulceration and inflammation, and altered barrier function. Following intestinal injury, IEC AMPK KO mice displayed a lower goblet cell counts with concomitant decreased Muc2 gene expression, unveiling an impaired restitution of goblet cells and contribution to wound healing process. Metformin administration during the recovery phase attenuated the severity of DSS-induced colitis through improvement in intestinal repair capacity in both WT and IEC AMPK KO mice. Taken together, these findings demonstrate a critical role for IEC-expressed AMPK in regulating mucosal repair and epithelial regenerative capacity following acute colonic injury. Our studies further underscore the therapeutic potential of metformin to support repair of the injured intestinal epithelium, but this effect is conferred independently of intestinal epithelial AMPK.

Linagliptin ameliorates acetic acid-induced colitis via modulating AMPK/SIRT1/PGC-1α and JAK2/STAT3 signaling pathway in rats

Ulcerative colitis is a chronic inflammatory disease, profoundly affecting the patient's quality of life and is associated with various complications. Linagliptin, a potent DPP- IV inhibitor, shows favorable anti-inflammatory effects in several animal model pathologies. To this end, the present study aimed to investigate the anti-inflammatory effect of linagliptin in a rat model of acetic acid-induced colitis. Moreover, the molecular mechanisms behind this effect were addressed. Accordingly, colitis was established by the administration of a 2 ml 6% acetic acid intrarectally and treatment with linagliptin (5 mg/kg) started 24 h after colitis induction and continued for 7 days. On one hand, the DPP-IV inhibitor alleviated the severity of colitis as evidenced by a decrease of disease activity index (DAI) scores, colon weight/length ratio, macroscopic damage, and histopathological deteriorations. Additionally, linagliptin diminished colon inflammation via attenuation of TNF-α, IL-6, and NF-κB p65 besides restoration of anti-inflammatory cytokine IL-10. On the other hand, linagliptin increased levels of p-AMPK, SIRT1, and PGC-1α while abolishing the increment in p-JAK2 and p-STAT3. In parallel linagliptin reduced mTOR levels and upregulated expression levels of SHP and MKP-1 which is postulated to mediate AMPK-driven JAK2/STAT3 inhibition. Based on these findings, linagliptin showed promising anti-inflammatory activity against acetic acid-induced colitis that is mainly attributed to the activation of the AMPK-SIRT1-PGC-1α pathway as well as suppression of the JAK2/STAT3 signaling pathway that might be partly mediated through AMPK activation.

AICAR decreases acute lung injury by phosphorylating AMPK and upregulating heme oxygenase-1

AIM

We investigated the mechanisms by which N1-(β-d-ribofuranosyl)-5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an activator of AMP-activated protein kinase (AMPK), decreases lung injury and mortality when administered to mice post exposure to bromine gas (Br2).

METHODS

We exposed male C57BL/6 mice and heme oxygenase-1 (HO-1)-deficient (HO-1-/-) and corresponding wild-type (WT) littermate mice to Br2 (600 ppm for 45 or 30 min, respectively) in environmental chambers and returned them to room air. AICAR was administered 6 h post exposure (10 mg·kg-1, intraperitoneal). We assessed survival, indices of lung injury, high mobility group box 1 (HMGB1) in the plasma, HO-1 levels in lung tissues and phosphorylation of AMPK and its upstream liver kinase B1 (LKB1). Rat alveolar type II epithelial (L2) cells and human club-like epithelial (H441) cells were also exposed to Br2 (100 ppm for 10 min). After 24 h we measured apoptosis and necrosis, AMPK and LKB1 phosphorylation, and HO-1 expression.

RESULTS

There was a marked downregulation of phosphorylated AMPK and LKB1 in lung tissues and in L2 and H441 cells post exposure. AICAR increased survival in C57BL/6 but not in HO-1-/- mice. In WT mice, AICAR decreased lung injury and restored phosphorylated AMPK and phosphorylated LKB1 to control levels and increased HO-1 levels in both lung tissues and cells exposed to Br2. Treatment of L2 and H441 cells with small interfering RNAs against nuclear factor erythroid 2-related factor 2 or HO-1 abrogated the protective effects of AICAR.

CONCLUSIONS

Our data indicate that the primary mechanism for the protective action of AICAR in toxic gas injury is the upregulation of lung HO-1 levels.

Preclinical Development of FA5, a Novel AMP-Activated Protein Kinase (AMPK) Activator as an Innovative Drug for the Management of Bowel Inflammation

Acadesine (ACA), a pharmacological activator of AMP-activated protein kinase (AMPK), showed a promising beneficial effect in a mouse model of colitis, indicating this drug as an alternative tool to manage IBDs. However, ACA displays some pharmacodynamic limitations precluding its therapeutical applications. Our study was aimed at evaluating the in vitro and in vivo effects of FA-5 (a novel direct AMPK activator synthesized in our laboratories) in an experimental model of colitis in rats. A set of experiments evaluated the ability of FA5 to activate AMPK and to compare the efficacy of FA5 with ACA in an experimental model of colitis. The effects of FA-5, ACA, or dexamethasone were tested in rats with 2,4-dinitrobenzenesulfonic acid (DNBS)-induced colitis to assess systemic and tissue inflammatory parameters. In in vitro experiments, FA5 induced phosphorylation, and thus the activation, of AMPK, contextually to the activation of SIRT-1. In vivo, FA5 counteracted the increase in spleen weight, improved the colon length, ameliorated macroscopic damage score, and reduced TNF and MDA tissue levels in DNBS-treated rats. Of note, FA-5 displayed an increased anti-inflammatory efficacy as compared with ACA. The novel AMPK activator FA-5 displays an improved anti-inflammatory efficacy representing a promising pharmacological tool against bowel inflammation.

Endothelial cell and T-cell crosstalk: Targeting metabolism as a therapeutic approach in chronic inflammation

The role of metabolic reprogramming in the coordination of the immune response has gained increasing consideration in recent years. Indeed, it has become clear that changes in the metabolic status of immune cells can alter their functional properties. During inflammation, T cells need to generate sufficient energy and biomolecules to support growth, proliferation, and effector functions. Therefore, T cells need to rearrange their metabolism to meet these demands. A similar metabolic reprogramming has been described in endothelial cells, which have the ability to interact with and modulate the function of immune cells. In this overview, we will discuss recent insights in the complex crosstalk between endothelial cells and T cells as well as their metabolic reprogramming following activation. We highlight key components of this metabolic switch that can lead to the development of new therapeutics against chronic inflammatory disorders. LINKED ARTICLES: This article is part of a themed issue on Cellular metabolism and diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.10/issuetoc.

Salicylates Ameliorate Intestinal Inflammation by Activating Macrophage AMPK

BACKGROUND

Inflammatory bowel diseases are the most common chronic intestinal inflammatory conditions, and their incidence has shown a dramatic increase in recent decades. Limited efficacy and questionable safety profiles with existing therapies suggest the need for better targeting of therapeutic strategies. Adenosine monophosphate-activated protein kinase (AMPK) is a key regulator of cellular metabolism and has been implicated in intestinal inflammation. Macrophages execute an important role in the generation of intestinal inflammation. Impaired AMPK in macrophages has been shown to be associated with higher production of proinflammatory cytokines; however, the role of macrophage AMPK in intestinal inflammation and the mechanism by which it regulates inflammation remain to be determined. In this study, we investigated the role of AMPK with a specific focus on macrophages in the pathogenesis of intestinal inflammation.

METHODS

A dextran sodium sulfate-induced colitis model was used to assess the disease activity index, histological scores, macroscopic scores, and myeloperoxidase level. Proinflammatory cytokines such as tumor necrosis factor-α, interleukin-6, and interleukin-1β were measured by enzyme-linked immunosorbent assay. Transient transfection of AMPKβ1 and LC3-II siRNA in RAW 264.7 cells was performed to elucidate the regulation of autophagy by AMPK. The expression of p-AMPK, AMPK, and autophagy markers (eg, LC3-II, p62, Beclin-1, and Atg-12) was analyzed by Western blot.

RESULTS

Genetic deletion of AMPKβ1 in macrophages upregulated the production of proinflammatory cytokines, aggravated the severity of dextran sodium sulfate-induced colitis in mice, which was associated with an increased nuclear translocation of nuclear factor-κB, and impaired autophagy both in vitro and in vivo. Notably, the commonly used anti-inflammatory 5-aminosalicylic acid (ie, mesalazine) and sodium salicylate ameliorated dextran sodium sulfate-induced colitis through the activation of macrophage AMPK targeting the β1 subunit.

CONCLUSIONS

Together, these data suggest that the development of therapeutic agents targeting AMPKβ1 may be effective in the treatment of intestinal inflammatory conditions including inflammatory bowel disease.

Mesalazine Activates Adenosine Monophosphate-activated Protein Kinase: Implication in the Anti-inflammatory Activity of this Anti-colitic Drug

OBJECTIVE

Mesalazine, 5-aminosalicylic acid (5-ASA), is an anti-inflammatory drug that is most widely used for the treatment of Inflammatory Bowel Disease (IBD). Despite extensive clinical use, the exact pharmacological mechanism underlying the anti-colitic effects of 5-ASA has not yet been elucidated. A potential molecular mechanism underlying 5-ASA-mediated anti-colitic activity was investigated.

METHODS

An anti-inflammatory pharmacology of 5-ASA was scrutinized in human colon carcinoma cells and murine macrophages and in a TNBS-induced rat colitis model.

RESULTS

5-ASA induced phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its substrate acetyl-CoA carboxylase in cells. 5-ASA activation of AMPK occurred regardless of the presence of the pro-inflammatory mediators, Tumor Necrosis Factor Alpha (TNF-α) and lipopolysaccharide. 5-ASA inhibits TNF-α-dependent Nuclear Factor-Kappa B (NF-κB) activation, which was dampened by AMPK inhibition. Oral gavage of sulfasalazine (a colon-specific prodrug of 5- ASA) or rectal administration of 5-ASA ameliorated 2,4,6-trinitrobenzene sulfonic acid (TNBS)- induced rat colitis and activated AMPK in the inflamed colonic tissues while markedly diminishing the levels of NF-κB-regulated pro-inflammatory mediators cyclooxygenase-2, inducible nitric oxide synthase, and cytokine-induced neutrophil chemoattractant-3, elevated by the induction of inflammation. Rectal co-administration of 5-ASA and an AMPK inhibitor undermined 5-ASA-mediated activation of AMPK and its anti-colitic effects.

CONCLUSION

These findings suggest that the activation of AMPK is involved in 5-ASA-mediated anticolitic effects at least partly via interference with pro-inflammatory NF-κB signaling.

Nrf2-SHP Cascade-Mediated STAT3 Inactivation Contributes to AMPK-Driven Protection Against Endotoxic Inflammation

Signal transducer and activator of transcription 3 (STAT3) is implicated in inflammation processing, but the mechanism of its regulation mostly remains limited to Janus kinase (JAK)-mediated phosphorylation. Although AMP-activated protein kinase (AMPK)-mediated STAT3 inactivation has got documented, the molecular signaling cascade connecting STAT3 inactivation and the anti-inflammatory role of AMPK is far from established. In the present study, we addressed the interplay between AMPK and STAT3, and revealed the important role of STAT3 inactivation in the anti-inflammatory function of AMPK in lipopolysaccharide-stressed macrophages and mice. Firstly, we found that pharmacological inhibition of STAT3 can improve the anti-inflammatory effect of AMPK in wild-type mice, and the expression of STAT3 in macrophage of mice is a prerequisite for the anti-inflammatory effect of AMPK. As to the molecular signaling cascade linking AMPK to STAT3, we disclosed that AMPK suppressed STAT3 not only by attenuating JAK signaling but also by activating nuclear factor erythroid-2-related factor-2 (Nrf2), a redox-regulating transcription factor, which consequently increased the expression of small heterodimer protein (SHP), thus repressing the transcriptional activity of STAT3. In summary, this study provided a unique set of evidence showing the relationship between AMPK and STAT3 signaling and explored a new mechanism of AMPK-driven STAT3 inactivation that involves Nrf2-SHP signaling cascade. These findings expand our understanding of the interplay between pro- and anti-inflammatory signaling pathways and are beneficial for the therapeutic development of sepsis treatments.

Targeting T Cell Metabolism in Inflammatory Skin Disease

A properly functioning T cell compartment is crucial to protect the host from infections, tumors, and environmental substances. In recent years, it has become increasingly clear that the processes underlying proper T cell activation, proliferation, and differentiation require well-tuned and dynamic changes in T cell metabolism. Thus, proper metabolic reprogramming in T cells is crucial to ensure proper immunity in the context of infection and anti-tumor immunity. Conversely, aberrant regulation of T cell metabolism can impair T cell function and thereby contribute to T cell-mediated disease. In this review, the relevance of recent insights into T cell metabolism for prototypical T cell-mediated skin diseases will be discussed and their therapeutic potential will be outlined. First, the major modules of T cell metabolism are summarized. Then, the importance of T cell metabolism for T cell-mediated skin diseases such as psoriasis and allergic contact dermatitis is discussed, based on the current state of our understanding thereof. Finally, novel therapeutic opportunities for inflammatory skin disease that might emerge from investigations in T cell metabolism are outlined.

Artemisinin alleviates atherosclerotic lesion by reducing macrophage inflammation via regulation of AMPK/NF-κB/NLRP3 inflammasomes pathway

There is increasing evidence that atherosclerosis is the significant risk factor for cardiovascular diseases, which are the leading causes of morbidity and mortality worldwide. Artemisinin is a natural endoperoxides quiterpene lactone compound in Artemisia annua L with vasculoprotective effects. The primary aim of this study was to investigate whether artemisinin could be conferred an anti-atherosclerotic effect in high-fat diet (HFD)-fed ApoE^-/- mice and explore the possible mechanism. We found that treatment with artemisinin (50 and 100 mg/kg) effectively ameliorated atherosclerotic lesions, such as foam cell formation, hyperplasia and fibrosis in the aortic intima. Atherosclerotic mice treated with artemisinin showed reduced inflammation by up-regulating adenosine 5'-monophosphate (AMP) activated protein kinase (AMPK) activation and by down-regulating nuclear factor-κB (NF-κB) phosphorylation and nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome expression in the aortas. In addition, artemisinin was found to promote AMPK activity in macrophages and its anti-inflammatory effect was neutralised by AMPK silence using specific siRNA. In conclusion, we demonstrate that artemisinin may protect the aortas from atherosclerotic lesions by suppression of inflammatory reaction via AMPK/NF-κB/NLRP3 inflammasomes signalling in macrophages.

Regulation of T cell immunity by cellular metabolism

T cells are an important adaptive immune response arm that mediates cell-mediated immunity. T cell metabolism plays a central role in T cell activation, proliferation, differentiation, and effector function. Specific metabolic programs are tightly controlled to mediate T cell immune responses, and alterations in T cell metabolism may result in many immunological disorders. In this review, we will summarize the main T cell metabolic pathways and the important factors participating in T cell metabolic programming during T cell homeostasis, differentiation, and function.

Intestinal Nucleoside Transporters: Function, Expression, and Regulation

The gastrointestinal tract is the absorptive organ for nutrients found in foods after digestion. Nucleosides and, to a lesser extent nucleobases, are the late products of nucleoprotein digestion. These metabolites are absorbed by nucleoside (and nucleobase) transporter (NT) proteins. NTs are differentially distributed along the gastrointestinal tract showing also polarized expression in epithelial cells. Concentrative nucleoside transporters (CNTs) are mainly located at the apical side of enterocytes, whereas equilibrative nucleoside transporters (ENTs) facilitate the basolateral efflux of nucleosides and nucleobases to the bloodstream. Moreover, selected nucleotides and the bioactive nucleoside adenosine act directly on intestinal cells modulating purinergic signaling. NT-polarized insertion is tightly regulated. However, not much is known about the modulation of intestinal NT function in humans, probably due to the lack of appropriate cell models retaining CNT functional expression. Thus, the possibility of nutritional regulation of intestinal NTs has been addressed using animal models. Besides the nutrition-related role of NT proteins, orally administered drugs also need to cross the intestinal barrier, this event being a major determinant of drug bioavailability. In this regard, NT proteins might also play a role in pharmacology, thereby allowing the absorption of nucleoside- and nucleobase-derived drugs. The relative broad selectivity of these membrane transporters also suggests clinically relevant drug-drug interactions when using combined therapies. This review focuses on all these physiological and pharmacological aspects of NT protein biology. © 2017 American Physiological Society. Compr Physiol 8:1003-1017, 2018.

Linking energy sensing to suppression of JAK-STAT signalling: A potential route for repurposing AMPK activators?

Exaggerated Janus kinase-signal transducer and activator of transcription (JAK-STAT) signalling is key to the pathogenesis of pro-inflammatory disorders, such as rheumatoid arthritis and cardiovascular diseases. Mutational activation of JAKs is also responsible for several haematological malignancies, including myeloproliferative neoplasms and acute lymphoblastic leukaemia. Accumulating evidence links adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), an energy sensor and regulator of organismal and cellular metabolism, with the suppression of immune and inflammatory processes. Recent studies have shown that activation of AMPK can limit JAK-STAT-dependent signalling pathways via several mechanisms. These novel findings support AMPK activation as a strategy for management of an array of disorders characterised by hyper-activation of the JAK-STAT pathway. This review discusses the pivotal role of JAK-STAT signalling in a range of disorders and how both established clinically used and novel AMPK activators might be used to treat these conditions.

Small molecules as therapy for uveitis: a selected perspective of new and developing agents

INTRODUCTION

Intraocular inflammation (uveitis) remains a significant burden of legal blindness. Because of its immune mediated and chronic recurrent nature, common therapy includes corticosteroids, disease-modifying anti-rheumatic drugs and more recently biologics as immune modulatory agents. The purpose of this article is to identify the role of new treatment approaches focusing on small molecules as therapeutic option in uveitis. Areas covered: A MEDLINE database search was conducted through February 2017 using the terms 'uveitis' and 'small molecule'. To provide ongoing and future perspectives in treatment options, also clinical trials as registered at ClinicalTrials.gov were included. Both, results from experimental as well as clinical research in this field were included. Since this field is rapidly evolving, a selection of promising agents had to be made. Expert opinion: Small molecules may interfere at different steps of the inflammatory cascade and appear as an interesting option in the treatment algorithm of uveitis. Because of their highly targeted molecular effects and their favorable bioavailability with the potential of topical application small molecules hold great promise. Nevertheless, a careful evaluation of these agents has to be made, since current experience is almost exclusively based on experimental uveitis models and few registered trials.

The Therapeutic Potential of T Cell Metabolism

Transplant rejection mediated by the adaptive immune system remains a major barrier to achieving long-term tolerance and graft survival. Emerging evidence indicates that lymphocytes rapidly shift their metabolic programs in response to activation, co-stimulatory, and cytokine signals to support required effector cell differentiation and function. These observations have led to the hypothesis that manipulating the metabolic programs of immune cells could serve as a powerful therapeutic strategy for attenuating deleterious immune responses and facilitating durable tolerance in the setting of allogeneic solid organ or bone marrow transplant. In this mini-review, we introduce the fundamentals of metabolism, highlight the current understanding of how adaptive immune cells utilize their metabolic programs, and discuss the potential for targeting metabolism as a therapeutic approach to induce tolerance in the transplant setting.

Intestinal mononuclear cells primed by systemic interleukin-12 display long-term ability to aggravate colitis in mice

To address whether the burst of systemic interleukin-12 (IL-12) influences intestinal inflammation elicited by luminal stimuli, we induced IL-12 release by cDNA injection in C57BL/6 mice and simultaneously started dextran sulphate sodium administration. The sequence of the inflammatory response triggered by IL-12 release was characterized by assessing myeloperoxidase activity and histological damage in colon samples on days 1, 3, 5 and 7 after colitis induction. To evaluate the persistence of IL-12 priming, colitis was induced in mice 7 or 60 days after cDNA injection. Under IL-12 influence, the development of acute colitis presented a faster and selective infiltration of inflammatory mononuclear cells in the lamina propria. Recruitment was driven by systemic cytokines rather than luminal antigens. Interestingly, when colitis was triggered 7 or 60 days after the cytokine storm, cells maintained the ability to worsen clinical signs of intestinal inflammation. Together, a systemic IL-12 burst effectively primed intestinal cells that became more prone to develop inflammatory responses. Activation was long-lasting because intestinal cells maintained their inflammatory potential and their ability to aggravate colitis.

Reduced mitochondrial activity in colonocytes facilitates AMPKα2-dependent inflammation

Intestinal inflammation is associated with low levels of mucosal ATP, highlighting the importance of mitochondrial function associated with ATP production in the pathophysiology of the disease. In the inflamed colon of humans and mice, we found decreased levels of mitochondrial complex cytochrome c oxidase I/IV and lower ATP levels. Thus, we generated colonic ρ⁰ cells with reduced mitochondrial function linked to ATP production by selective depletion of mitochondrial DNA. In these cells, RNA sequencing revealed a substantial number of differentially expressed transcripts, among which 240 belonged to inflammatory pathways activated in human inflamed colon and TNF-α-treated cells (false discovery rate < 0.05). TNF-α treatment of colonic ρ⁰ cells augmented IL-8 expression by 9-fold (P < 0.01) via NF-κB compared to TNF-α-treated control. Moreover, reduced mitochondrial function facilitated TNF-α-mediated NF-κB luciferase promoter activity as a result of lowered inhibitory IκBα (nuclear factor of κ light polypeptide gene enhancer in B-cell inhibitor, α), leading to elevated NF-κB. In cells with reduced mitochondrial function, TNF-α facilitated AMPKα2 activation by 8-fold (P < 0.01), which was involved in NF-κB-dependent IL-8 expression. Last, in human and mouse colon, anti-TNF-α treatment restored reduced mitochondria-dependent inflammation. We propose that selective targeting of this novel mechanism provides new treatment opportunities for intestinal inflammation.-Heller, S., Penrose, H. M., Cable, C., Biswas, D., Nakhoul, H., Baddoo, M., Flemington, E., Crawford, S. E., Savkovic, S. D. Reduced mitochondrial activity in colonocytes facilitates AMPKα2-dependent inflammation.

Metabolic pathways in T cell activation and lineage differentiation

Recent advances in the field of immunometabolism support the concept that fundamental processes in T cell biology, such as TCR-mediated activation and T helper lineage differentiation, are closely linked to changes in the cellular metabolic programs. Although the major task of the intermediate metabolism is to provide the cell with a constant supply of energy and molecular precursors for the production of biomolecules, the dynamic regulation of metabolic pathways also plays an active role in shaping T cell responses. Key metabolic processes such as glycolysis, fatty acid and mitochondrial metabolism are now recognized as crucial players in T cell activation and differentiation, and their modulation can differentially affect the development of T helper cell lineages. In this review, we describe the diverse metabolic processes that T cells engage during their life cycle from naïve towards effector and memory T cells. We consider in particular how the cellular metabolism may actively support the function of T cells in their different states. Moreover, we discuss how molecular regulators such as mTOR or AMPK link environmental changes to adaptations in the cellular metabolism and elucidate the consequences on T cell differentiation and function.

A concise review on advances in development of small molecule anti-inflammatory therapeutics emphasising AMPK: An emerging target

Inflammatory diseases are complex, multi-factorial outcomes of evolutionarily conserved tissue repair processes. For decades, non-steroidal anti-inflammatory drugs and cyclooxygenase inhibitors, the primary drugs of choice for the management of inflammatory diseases, addressed individual targets in the arachidonic acid pathway. Unsatisfactory safety and efficacy profiles of the above have necessitated the development of multi-target agents to treat complex inflammatory diseases. Current anti-inflammatory therapies still fall short of clinical needs and the clinical trial results of multi-target therapeutics are anticipated. Additionally, new drug targets are emerging with improved understanding of molecular mechanisms controlling the pathophysiology of inflammation. This review presents an outline of small molecules and drug targets in anti-inflammatory therapeutics with a summary of a newly identified target AMP-activated protein kinase, which constitutes a novel therapeutic pathway in inflammatory pathology.

T-cell metabolism governing activation, proliferation and differentiation; a modular view

T lymphocytes are a critical component of the adaptive immune system mediating protection against infection and malignancy, but also implicated in many immune pathologies. Upon recognition of specific antigens T cells clonally expand, traffic to inflamed sites and acquire effector functions, such as the capacity to kill infected and malignantly transformed cells and secrete cytokines to coordinate the immune response. These processes have significant bioenergetic and biosynthetic demands, which are met by dynamic changes in T-cell metabolism, specifically increases in glucose uptake and metabolism; mitochondrial function; amino acid uptake, and cholesterol and lipid synthesis. These metabolic changes are coordinate by key cellular kinases and transcription factors. Dysregulated T-cell metabolism is associated with impaired immunity in chronic infection and cancer and conversely with excessive T-cell activity in autoimmune and inflammatory pathologies. Here we review the key aspects of T-cell metabolism relevant to their immune function, and discuss evidence for the potential to therapeutically modulate T-cell metabolism in disease.

The AMP analog AICAR modulates the Treg/Th17 axis through enhancement of fatty acid oxidation

T cells must tightly regulate their metabolic processes to cope with varying bioenergetic demands depending on their state of differentiation. The metabolic sensor AMPK is activated in states of low energy supply and modulates cellular metabolism toward a catabolic state. Although this enzyme is known to be particularly active in regulatory T (T_reg) cells, its impact on T helper (T_h)-cell differentiation is poorly understood. We investigated the impact of several AMPK activators on T_reg-cell differentiation and found that the direct activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), but not the indirect activators metformin and 2-deoxyglucose, strongly enhanced T_reg-cell induction by specifically enhancing T_reg-cell expansion. Conversely, T_h17 generation was impaired by the agent. Further investigation of the metabolic background of our observations revealed that AICAR enhanced both cellular mitochondrogenesis and fatty acid uptake. Consistently, increased T_reg induction was entirely reversible on inhibition of fatty acid oxidation, thus confirming the dependence of AICAR's effects on metabolic pathways alterations. Translating our findings to an in vivo model, we found that the substance enhanced T_reg cell generation on IL-2 complex-induced immune stimulation. We provide a previously unrecognized insight into the delicate interplay between immune cell function and metabolism and delineate a potential novel strategy for metabolism-targeting immunotherapy.-Gualdoni, G. A., Mayer, K. A., Göschl, L., Boucheron, N., Ellmeier, W., Zlabinger, G. J. The AMP analog AICAR modulates the T_reg/T_h17 axis through enhancement of fatty acid oxidation.

5-Aminoimidazole-4-carboxamide ribonucleoside-mediated adenosine monophosphate-activated protein kinase activation induces protective innate responses in bacterial endophthalmitis

The retina is considered to be the most metabolically active tissue in the body. However, the link between energy metabolism and retinal inflammation, as incited by microbial infection such as endophthalmitis, remains unexplored. In this study, using a mouse model of Staphylococcus aureus (SA) endophthalmitis, we demonstrate that the activity (phosphorylation) of 5' adenosine monophosphate-activated protein kinase alpha (AMPKα), a cellular energy sensor and its endogenous substrate; acetyl-CoA carboxylase is down-regulated in the SA-infected retina. Intravitreal administration of an AMPK activator, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), restored AMPKα and acetyl-CoA carboxylase phosphorylation. AICAR treatment reduced both the bacterial burden and intraocular inflammation in SA-infected eyes by inhibiting NF-kB and MAP kinases (p38 and JNK) signalling. The anti-inflammatory effects of AICAR were diminished in eyes pretreated with AMPK inhibitor, Compound C. The bioenergetics (Seahorse) analysis of SA-infected microglia and bone marrow-derived macrophages revealed an increase in glycolysis, which was reinstated by AICAR treatment. AICAR also reduced the expression of SA-induced glycolytic genes, including hexokinase 2 and glucose transporter 1 in microglia, bone marrow-derived macrophages and the mouse retina. Interestingly, AICAR treatment enhanced the bacterial phagocytic and intracellular killing activities of cultured microglia, macrophages and neutrophils. Furthermore, AMPKα1 global knockout mice exhibited increased susceptibility towards SA endophthalmitis, as evidenced by increased inflammatory mediators and bacterial burden and reduced retinal function. Together, these findings provide the first evidence that AMPK activation promotes retinal innate defence in endophthalmitis by modulating energy metabolism and that it can be targeted therapeutically to treat ocular infections.

Links of Autophagy Dysfunction to Inflammatory Bowel Disease Onset

INTRODUCTION

Autophagy is a cellular stress response that plays key roles in physiological processes, such as adaptation to starvation, degradation of aberrant proteins or organelles, anti-microbial defense, protein secretion, and innate and adaptive immunity. Dysfunctional autophagy is recognized as a contributing factor in many chronic inflammatory diseases, including inflammatory bowel disease (IBD). Genetic studies have identified multiple IBD-associated risk loci that include genes required for autophagy, and several lines of evidence demonstrate that autophagy is impaired in IBD patients. How dysfunctional autophagy contributes to IBD onset is currently under investigation by researchers.

KEY MESSAGES

Dysfunctional autophagy has been identified to play a role in IBD pathogenesis by altering processes that include (1) intracellular bacterial killing, (2) anti-microbial peptide secretion by Paneth cells, (3) pro-inflammatory cytokine production by macrophages, (4) antigen presentation by dendritic cells, (5) goblet cell function, and (6) the endoplasmic reticulum stress response in enterocytes. The overall effect of dysregulation of these processes varies by cell type, stimulus, as well as cellular context. Manipulation of the autophagic pathway may provide a new avenue in the search for effective therapies for IBD.

CONCLUSION

Autophagy plays multiple roles in IBD pathogenesis. A better understanding of the role of autophagy in IBD patients may provide better subclassification of IBD phenotypes and novel approaches to disease management.

NADH oxidase-dependent CD39 expression by CD8(+) T cells modulates interferon gamma responses via generation of adenosine

Interferon gamma (IFNγ)-producing CD8⁺ T cells (Tc1) play important roles in immunological disease. We now report that CD3/CD28-mediated stimulation of CD8⁺ T cells to generate Tc1 cells, not only increases IFNγ production but also boosts the generation of reactive oxygen species (ROS) and augments expression of CD39. Inhibition of NADPH oxidases or knockdown of gp91phox in CD8⁺ T cells abrogates ROS generation, which in turn modulates JNK and NFκB signalling with decreases in both IFNγ levels and CD39 expression. CD39⁺CD8⁺ T cells substantially inhibit IFNγ production by CD39⁻CD8⁺ T cells via the paracrine generation of adenosine, which is operational via adenosine type 2A receptors. Increases in numbers of CD39⁺CD8⁺ T cells and associated enhancements in ROS signal transduction are noted in cells from patients with Crohn's disease. Our findings provide insights into Tc1-mediated IFNγ responses and ROS generation and link these pathways to CD39/adenosine-mediated effects in immunological disease.

The ectonucleotidase CD39 ultimately generates extracellular adenosine, modulating paracrine purinergic signaling. Here the authors show that IFNγ induction in CD8+ T cells is accompanied by NADH oxidase-dependent CD39 expression, which then inhibits IFNγ production in CD39-CD8+ T cells.

AMPK Activation by A-769662 Controls IL-6 Expression in Inflammatory Arthritis

Objective

AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase critically involved in the regulation of cellular energy homeostasis. It is a central regulator of both lipid and glucose metabolism. Many studies have suggested that AMPK activation exert significant anti-inflammatory and immunosuppressive effects. In this study, we assessed whether targeted activation of AMPK inhibits inflammatory arthritis in vivo.

Methods

We tested the effect of A-769662, a specific AMPK agonist (60mg/kg/bid) in mouse models of antigen-induced arthritis (AIA) and passive K/BxN serum-induced arthritis. The passive K/BxN serum-induced arthritis model was also applied to AMPKα1-deficient mice. Joints were harvested and subjected to histological analysis. IL-6 expression was measured in both joint tissues and sera by ELISA. The effect of A-769662 on bone marrow derived macrophage (BMDM) response to stimulation with TLR2 and TLR4 agonists was tested in vitro.

Results

AMPK activation by A-769662 reduced inflammatory infiltration and joint damage in both mouse models. IL-6 expression in serum and arthritic joints was significantly decreased in A-769662-treated mice. AMPKα1 deficient mice mildly elicited an increase of clinical arthritis. IL-6 expression at both mRNA and protein levels, phosphorylation of p65 NF-κB and MAPK phosphorylation were inhibited by A-769662 in BMDMs stimulated with either TLR2 or TLR4 agonists.

Conclusions

AMPK activation by specific AMPK agonist A-769662 suppressed inflammatory arthritis in mice as well as IL-6 expression in serum and arthritic joints. These data suggest that targeted activation of AMPK has a potential to be an effective therapeutic strategy for IL-6 dependent inflammatory arthritis.

5-Aminoimidazole-4-carboxamide-1-β-D-ribofuranoside-attenuates LPS/D-Gal-induced acute hepatitis in mice

The AMP-activated protein kinase (AMPK)-mediated energy-sensing signals play important roles in reprogramming the expression of inflammatory genes. In the present study, the potential effects of the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) were investigated in a mouse model with LPS/D-Gal-induced acute hepatitis. Our experimental data indicated that treatment with AICAR suppressed the elevation of plasma aminotransferases and alleviated the histopathological abnormalities in mice exposed to LPS/D-Gal. Treatment with AICAR also inhibited the LPS/D-Gal-induced up-regulation of TNF-α, NO and myeloperoxidase. In addition, the LPS/D-Gal-induced expression of pro-apoptotic factor Bax, cleavage of caspase-3, elevation of hepatic caspase-3, caspase-8, caspase-9 activities and induction of terminal deoxynucleotidyl transferase-mediated nucleotide nick-end labeling-positive cells were all suppressed by AICAR. These results suggested that the AMPK activator AICAR could attenuate LPS/D-Gal-induced acute hepatitis, which implies that AMPK might become a novel target for the treatment of inflammation-based liver disorders.

6-Gingerol modulates proinflammatory responses in dextran sodium sulfate (DSS)-treated Caco-2 cells and experimental colitis in mice through adenosine monophosphate-activated protein kinase (AMPK) activation

BACKGROUND

6-gingerol has been reported to have anti-inflammatory effects in different experimental settings. The present study aimed at evaluating the effect of 6-gingerol on dextran sodium sulfate (DSS)-induced barrier impairment and inflammation in vitro and in vivo.

METHODS

a differentiated Caco-2 monolayer was exposed to DSS and treated with different concentrations of 6-gingerol (0, 1, 5, 10, 50, and 100 μM). Changes in intestinal barrier function were determined using transepithelial electrical resistance (TEER). The anti-inflammatory activity of 6-gingerol was examined as changes in the expression of proinflammatory cytokine using quantitative real-time PCR. Western blotting was employed to determine the activation of adenosine monophosphate-activated protein kinase (AMPK). Mice with DSS-induced colitis were given different oral dosages of 6-gingerol daily for 14 days. Body weight and colon inflammation were evaluated, and level of proinflammatory cytokines in colon tissues was measured.

RESULTS

6-gingerol treatment was shown to restore impaired intestinal barrier function and to suppress proinflammatory responses in DSS-treated Caco-2 monolayers. We found that AMPK was activated on 6-gingerol treatment in vitro. In animal studies, 6-gingerol significantly ameliorated DSS-induced colitis by restoration of body weight loss, reduction in intestinal bleeding, and prevention of colon length shortening. In addition, 6-gingerol suppressed DSS-elevated production of proinflammatory cytokines (IL-1β, TNFα, and IL-12).

CONCLUSION

our findings highlight the protective effects of 6-gingerol against DSS-induced colitis. We concluded that 6-gingerol exerts anti-inflammatory effects through AMPK activation. It is suggested that 6-gingerol has a promising role in treatment of IBD.

Multi-target drugs to address multiple checkpoints in complex inflammatory pathologies: evolutionary cues for novel "first-in-class" anti-inflammatory drug candidates: a reviewer's perspective

Inflammation is a complex, metabolically expensive process involving multiple signaling pathways and regulatory mechanisms which have evolved over evolutionary timescale. Addressing multiple targets of inflammation holistically, in moderation, is probably a more evolutionarily viable strategy, as compared to current therapy which addresses drug targets in isolation. Polypharmacology, addressing multiple targets, is commonly used in complex ailments, suggesting the superior safety and efficacy profile of multi-target (MT) drugs. Phenotypic drug discovery, which generated successful MT and first-in-class drugs in the past, is now re-emerging. A multi-pronged approach, which modulates the evolutionarily conserved, robust and pervasive cellular mechanisms of tissue repair, with AMPK at the helm, regulating the complex metabolic/immune/redox pathways underlying inflammation, is perhaps a more viable strategy than addressing single targets in isolation. Molecules that modulate multiple molecular mechanisms of inflammation in moderation (modulating TH cells toward the anti-inflammatory phenotype, activating AMPK, stimulating Nrf2 and inhibiting NFκB) might serve as a model for a novel Darwinian "first-in-class" therapeutic category that holistically addresses immune, redox and metabolic processes associated with inflammatory repair. Such a multimodal biological activity is supported by the fact that several non-calorific pleiotropic natural products with anti-inflammatory action have been incorporated into diet (chiefly guided by the adaptive development of olfacto-gustatory preferences over evolutionary timescales) rendering such molecules, endowed with evolutionarily privileged molecular scaffolds, naturally oriented toward multiple targets.

Metformin attenuates hyperoxia-induced lung injury in neonatal rats by reducing the inflammatory response

Because therapeutic options are lacking for bronchopulmonary dysplasia (BPD), there is an urgent medical need to discover novel targets/drugs to treat this neonatal chronic lung disease. Metformin, a drug commonly used to lower blood glucose in type 2 diabetes patients, may be a novel therapeutic option for BPD by reducing pulmonary inflammation and fibrosis and improving vascularization. We investigated the therapeutic potential of daily treatment with 25 and 100 mg/kg metformin, injected subcutaneously in neonatal Wistar rats with severe experimental BPD, induced by continuous exposure to 100% oxygen for 10 days. Parameters investigated included survival, lung and heart histopathology, pulmonary fibrin and collagen deposition, vascular leakage, right ventricular hypertrophy, and differential mRNA expression in the lungs of key genes involved in BPD pathogenesis, including inflammation, coagulation, and alveolar development. After daily metformin treatment rat pups with experimental BPD had reduced mortality, alveolar septum thickness, lung inflammation, and fibrosis, demonstrated by a reduced influx of macrophages and neutrophils and hyperoxia-induced collagen III and fibrin deposition (25 mg/kg), as well as improved vascularization (100 mg/kg) compared with control treatment. However, metformin did not ameliorate alveolar enlargement, small arteriole wall thickening, vascular alveolar leakage, and right ventricular hypertrophy. In conclusion metformin prolongs survival and attenuates pulmonary injury by reducing pulmonary inflammation, coagulation, and fibrosis but does not affect alveolar development or prevent pulmonary arterial hypertension and right ventricular hypertrophy in neonatal rats with severe hyperoxia-induced experimental BPD.

AICAR attenuates organ injury and inflammatory response after intestinal ischemia and reperfusion

Intestinal ischemia and reperfusion (I/R) is encountered in various clinical conditions and contributes to multiorgan failure and mortality as high as 60% to 80%. Intestinal I/R not only injures the intestine, but affects remote organs such as the lung leading to acute lung injury. The development of novel and effective therapies for intestinal I/R are critical for the improvement of patient outcome. AICAR (5-aminoimidazole-4-carboxyamide ribonucleoside) is a cell-permeable compound that has been shown to possess antiinflammatory effects. The objective is to determine that treatment with AICAR attenuates intestinal I/R injury and subsequent acute lung injury (ALI). Male Sprague Dawley rats (275 to 325 g) underwent intestinal I/R injury with blockage of the superior mesenteric artery for 90 min and subsequent reperfusion. At the initiation of reperfusion, vehicle or AICAR (30 mg/kg BW) was given intravenously (IV) for 30 min. At 4 h after reperfusion, blood and tissues were collected for further analyses. Treatment with AICAR significantly decreased the gut damage score and the water content, indicating improvement in histological integrity. The treatment also attenuated tissue injury and proinflammatory cytokines, and reduced bacterial translocation to the gut. AICAR administration after intestinal I/R maintained lung integrity, attenuated neutrophil chemotaxis and infiltration to the lungs and decreased lung levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6. Inflammatory mediators, lung-inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins, were decreased in the lungs and lung apoptosis was significantly reduced after AICAR treatment. These data indicate that AICAR could be developed as an effective and novel therapeutic for intestinal I/R and subsequent ALI.

The new 4-O-methylhonokiol analog GS12021 inhibits inflammation and macrophage chemotaxis: role of AMP-activated protein kinase α activation

Preventing pathologic tissue inflammation is key to treating obesity-induced insulin resistance and type 2 diabetes. Previously, we synthesized a series of methylhonokiol analogs and reported that compounds with a carbamate structure had inhibitory function against cyclooxygenase-2 in a cell-free enzyme assay. However, whether these compounds could inhibit the expression of inflammatory genes in macrophages has not been investigated. Here, we found that a new 4-O-methylhonokiol analog, 3′,5-diallyl-4′-methoxy-[1,1′-biphenyl]-2-yl morpholine-4-carboxylate (GS12021) inhibited LPS- or TNFα-stimulated inflammation in macrophages and adipocytes, respectively. LPS-induced phosphorylation of nuclear factor-kappa B (NF-κB)/p65 was significantly decreased, whereas NF-κB luciferase activities were slightly inhibited, by GS12021 treatment in RAW 264.7 cells. Either mitogen-activated protein kinase phosphorylation or AP-1 luciferase activity was not altered by GS12021. GS12021 increased the phosphorylation of AMP-activated protein kinase (AMPK) α and the expression of sirtuin (SIRT) 1. Inhibition of mRNA expression of inflammatory genes by GS12021 was abolished in AMPKα1-knockdown cells, but not in SIRT1 knockout cells, demonstrating that GS12021 exerts anti-inflammatory effects through AMPKα activation. The transwell migration assay results showed that GS12021 treatment of macrophages prevented the cell migration promoted by incubation with conditioned medium obtained from adipocytes. GS12021 suppression of p65 phosphorylation and macrophage chemotaxis were preserved in AMPKα1-knockdown cells, indicating AMPK is not required for these functions of GS12021. Identification of this novel methylhonokiol analog could enable studies of the structure-activity relationship of this class of compounds and further evaluation of its in vivo potential for the treatment of insulin-resistant states and other chronic inflammatory diseases.

Targeting T cell metabolism for therapy

In the past several years a wealth of evidence has emerged illustrating how metabolism supports many aspects of T cell biology, as well as how metabolic changes drive T cell differentiation and fate. We outline developing principles in the regulation of T cell metabolism, and discuss how these processes are affected in settings of inflammation and cancer. In this context we discuss how metabolic pathways might be manipulated for the treatment of human disease, including how metabolism may be targeted to prevent T cell dysfunction in inhospitable microenvironments, to generate more effective adoptive cellular immunotherapies in cancer, and to direct T cell differentiation and function towards non-pathogenic phenotypes in settings of autoimmunity.

Fatty acid metabolism in the regulation of T cell function

The specific regulation of cellular metabolic processes is of major importance for directing immune cell differentiation and function. We review recent evidence indicating that changes in basic cellular lipid metabolism have critical effects on T cell proliferation and cell fate decisions. While induction of de novo fatty acid (FA) synthesis is essential for activation-induced proliferation and differentiation of effector T cells, FA catabolism via β-oxidation is important for the development of CD8(+) T cell memory as well as for the differentiation of CD4(+) regulatory T cells. We consider the influence of lipid metabolism and metabolic intermediates on the regulation of signaling and transcriptional pathways via post-translational modifications, and discuss how an improved understanding of FA metabolism may reveal strategies for manipulating immune responses towards therapeutic outcomes.

Integrating canonical and metabolic signalling programmes in the regulation of T cell responses

Over the past decade, our understanding of T cell activation, differentiation and function has markedly expanded, providing a greater appreciation of the signals and pathways that regulate these processes. It has become clear that evolutionarily conserved pathways that regulate stress responses, metabolism, autophagy and survival have crucial and specific roles in regulating T cell responses. Recent studies suggest that the metabolic pathways involving MYC, hypoxia-inducible factor 1α (HIF1α), AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) are activated upon antigen recognition and that they are required for directing the consequences of T cell receptor engagement. The purpose of this Review is to provide an integrated view of the role of these metabolic pathways and of canonical T cell signalling pathways in regulating the outcome of T cell responses.