DHA, RvD1, RvD5, and MaR1 reduce human coronary arteries contractions induced by PGE2.

In patients with coronary artery disease (CAD), plasma levels of pro-inflammatory lipid mediators such as PGE2 and TxA2 are increased. They could increase vascular contraction while EPA and DHA could reduce it. Studies have been mostly conducted on animal vessels. Therefore, the aim of the study was to investigate if EPA, DHA, and DHA-derived metabolites: RvD1, RvD5 and MaR1 can modulate contraction of human coronary arteries (HCA) induced by PGE2 or TxA2 stable analogue (U46619). DHA and EPA relaxed HCA pre-contracted with PGE2. 18 h-incubation with DHA but not EPA reduced the PGE2-induced contractions. Pre-incubation with RvD1, RvD5 and MaR1 reduced the PGE2-induced contractions. Indomethacin did not significantly modify the PGE2 responses. L-NOARG (inhibitor of nitric oxide synthase), reduced only the PGE2-induced contractions in RvD1-treated rings. Finally, FPR2/ALX, GPR32 and LGR6 receptors are detected in HCA by immunofluorescence. Our results indicate that DHA and its metabolites could be beneficial for HCA blood flow and could be a therapeutic perspective for patients with CAD.

Quantification and Potential Functions of Endogenous Agonists of Transient Receptor Potential Channels in Patients With Irritable Bowel Syndrome.

BACKGROUND & AIMS: In mice, activation of the transient receptor potential cation channels (TRP) TRPV1, TRPV4, and TRPA1 causes visceral hypersensitivity. These receptors and their agonists might be involved in development of irritable bowel syndrome (IBS). We investigated whether polyunsaturated fatty acid (PUFA) metabolites, which activate TRPs, are present in colon tissues from patients with IBS and act as endogenous agonists to induce hypersensitivity. METHODS: We analyzed colon biopsy samples from 40 patients with IBS (IBS biopsies) and 11 healthy individuals undergoing colorectal cancer screening (controls), collected during colonoscopy at the University of Bologna, Italy. Levels of the PUFA metabolites that activate TRPV1 (12-hydroperoxyeicosatetraenoic acid, 15-hydroxyeicosatetraenoic acid, 5-hydroxyeicosatetraenoic acid, and leukotriene B4), TRPV4 (5,6-epoxyeicosatrienoic acid [EET] and 8,9-EET), and TRPA1 (PGA1, 8-iso-prostaglandin A2, and 15-deoxy-Δ-prostaglandin J2) were measured in biopsies and their supernatants using liquid chromatography and tandem mass spectrometry; we also measured levels of the PUFA metabolites prostaglandin E2 (PGE2) and resolvins. C57Bl6 mice were given intrathecal injections of small interfering RNAs to reduce levels of TRPV4, or control small interfering RNAs, along with colonic injections of biopsy supernatants; visceral hypersensitivity was measured based on response to colorectal distension. Mouse sensory neurons were cultured and incubated with biopsy supernatants and lipids extracted from biopsies or colons of mice. Immunohistochemistry was used to detect TRPV4 in human dorsal root ganglia samples (from the National Disease Research Interchange). RESULTS: Levels of the TRPV4 agonist 5,6-EET, but not levels of TRPV1 or TRPA1 agonists, were increased in IBS biopsies compared with controls; increases correlated with pain and bloating scores. Supernatants from IBS biopsies, but not from controls, induced visceral hypersensitivity in mice. Small interfering RNA knockdown of TRPV4 in mouse primary afferent neurons inhibited the hypersensitivity caused by supernatants from IBS biopsies. Levels of 5,6-EET and 15-HETE were increased in colons of mice with, but not without, visceral hypersensitivity. PUFA metabolites extracted from IBS biopsies or colons of mice with visceral hypersensitivity activated mouse sensory neurons in vitro, by activating TRPV4. Mouse sensory neurons exposed to supernatants from IBS biopsies produced 5,6-EET via a mechanism that involved the proteinase-activated receptor-2 and cytochrome epoxygenase. In human dorsal root ganglia, TPV4 was expressed by 35% of neurons. CONCLUSIONS: Colon tissues from patients with IBS have increased levels of specific PUFA metabolites. These stimulate sensory neurons from mice and generate visceral hypersensitivity via activation of TRPV4.

Molecular and cellular profiles of the resolution phase in a damage-associated molecular pattern (DAMP)-mediated peritonitis model and revelation of leukocyte persistence in peritoneal tissues.

Models of microbe-elicited peritonitis have been invaluable to identify mechanisms underlying inflammation resolution, but whether resolution mechanisms differ from an inflammatory agent to another has not been determined. Thus, we analyzed the cellular and molecular components of the resolution phase of non-microbe-induced inflammation. In thioglycollate (TG)-induced peritonitis, resolution started at 12 h (Tmax) and displayed a 22 h resolution interval (Ri). During resolution, lipoxin A4, resolvin (Rv) D1 and RvD2, protectin D1 (PD1), and maresin 1 (MaR1) were transiently produced while RvD5 was continually generated. In addition, docosahexaenoic acid (DHA)-derived mediators were produced to a higher extent than in microbial peritonitis. We also investigated leukocyte infiltration and clearance in peritoneal tissues surrounding the inflammatory site. In the omentum, resolution parameters, neutrophil apoptosis, and efferocytosis were similar to those of the peritoneal cavity. However, we noticed long-term persistence of M2-polarized macrophages and B-lymphocytes in the omentum after TG administration, whereas zymosan injection caused M1/M2-macrophage and T-lymphocyte persistence regardless of the magnitude of the inflammatory response. Our study indicates that some aspects of resolution are shaped in a stimulus-specific manner, and it ultimately argues that the tissues surrounding the inflammatory site must also be considered to address the inflammatory response globally.

Proteomic and Lipidomic Profiling of Calves Experimentally Co-Infected with Influenza D Virus and Mycoplasma bovis: Insights into the Host-Pathogen Interactions.

The role of Influenza D virus (IDV) in bovine respiratory disease remains unclear. An in vivo experiment resulted in increased clinical signs, lesions, and pathogen replication in calves co-infected with IDV and Mycoplasma bovis (M. bovis), compared to single-infected calves. The present study aimed to elucidate the host-pathogen interactions and profile the kinetics of lipid mediators in the airways of these calves. Bronchoalveolar lavage (BAL) samples collected at 2 days post-infection (dpi) were used for proteomic analyses by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Additionally, lipidomic analyses were performed by LC-MS/MS on BAL samples collected at 2, 7 and 14 dpi. Whereas M. bovis induced the expression of proteins involved in fibrin formation, IDV co-infection counteracted this coagulation mechanism and downregulated other acute-phase response proteins, such as complement component 4 (C4) and plasminogen (PLG). The reduced inflammatory response against M. bovis likely resulted in increased M. bovis replication and delayed M. bovis clearance, which led to a significantly increased abundance of oxylipids in co-infected calves. The identified induced oxylipids mainly derived from arachidonic acid; were likely oxidized by COX-1, COX-2, and LOX-5; and peaked at 7 dpi. This paper presents the first characterization of BAL proteome and lipid mediator kinetics in response to IDV and M. bovis infection in cattle and raises hypotheses regarding how IDV acts as a co-pathogen in bovine respiratory disease.

CF Patients' Airway Epithelium and Sex Contribute to Biosynthesis Defects of Pro-Resolving Lipids.

Specialized pro-resolving lipid mediators (SPMs) as lipoxins (LX), resolvins (Rv), protectins (PD) and maresins (MaR) promote the resolution of inflammation. We and others previously reported reduced levels of LXA4 in bronchoalveolar lavages from cystic fibrosis (CF) patients. Here, we investigated the role of CF airway epithelium in SPMs biosynthesis, and we evaluated its sex specificity. Human nasal epithelial cells (hNEC) were obtained from women and men with or without CF. Lipids were quantified by mass spectrometry in the culture medium of hNEC grown at air-liquid interface and the expression level and localization of the main enzymes of SPMs biosynthesis were assessed. The 5-HETE, LXA4, LXB4, RvD2, RvD5, PD1 and RvE3 levels were significantly lower in samples derived from CF patients compared with non-CF subjects. Within CF samples, the 12-HETE, 15-HETE, RvD3, RvD4, 17-HODHE and PD1 were significantly lower in samples derived from females. While the mean expression levels of 15-LO, 5-LO and 12-LO do not significantly differ either between CF and non-CF or between female and male samples, the SPMs content correlates with the level of expression of several enzymes involved in SPMs metabolism. In addition, the 5-LO localization significantly differed from cytoplasmic in non-CF to nucleic (or nuclear envelope) in CF hNEC. Our studies provided evidence for lower abilities of airway epithelial cells derived from CF patients and more markedly, females to produce SPMs. These data are consistent with a contribution of CF airway epithelium in the abnormal resolution of inflammation and with worse pulmonary outcomes in women.

The Natural Combination Medicine Traumeel (Tr14) Improves Resolution of Inflammation by Promoting the Biosynthesis of Specialized Pro-Resolving Mediators.

The resolution of inflammation is an integral part of the acute inflammatory response and eventually leads to the return to homeostasis. It is supported by specialized pro-resolving mediators (SPMs) that act as immunoresolvents via specific G-protein-coupled receptors. In contrast to classical non-steroidal anti-inflammatory drugs (NSAIDs) that suppress the formation of pro-inflammatory lipid mediators such as prostaglandins, novel pharmacotherapeutic concepts propose to foster the biosynthesis of beneficial SPMs. Here, we demonstrate that the natural combination medicine Traumeel (Tr14) improves resolution of inflammation by promoting SPM formation. Tr14 enhanced the biosynthesis of 12-/15-lipoxygenase (LOX) products and of SPMs in zymosan-induced mouse peritonitis as well as in human monocyte-derived macrophages challenged with Staphylococcus aureus. Importantly, in the peritonitis model, Tr14 supported the recruitment of innate leukocytes and the efferocytotic capacity of macrophages, and positively influenced the inflammation resolution index. Taken together, we suggest that based on these properties Tr14 may possess therapeutic potential as an enhancer for the resolution of inflammatory processes.

[Roles of PPAR and p21WAF1/CIP1 in monocyte/macrophage differentiation: are circulating monocytes able to proliferate?]. / Rôles de PPAR et de p21WAF1/CIP1 dans la différenciation monocyte/macrophage: les monocytes circulants prolifèrent-ils?

Macrophages are involved in the immune and the inflammatory response. The deregulation of their physiological properties is associated with several pathologies such as atherosclerosis and some cancers. Cytokines action on this blood lineage modulates p21WAF1/CIP1 expression. It appears that this protein may play a role in the inflammation regulation through PPAR (peroxysome proliferator-activated receptors) transcription factors, strongly linked to lipid metabolism. It could also be involved in the control of the proliferation of monocytes/macrophages, even if these cells are classically described as devoided of any proliferative capacity.

Resolvin D1 Reduces Lung Infection and Inflammation Activating Resolution in Cystic Fibrosis.

Non-resolving lung inflammation and Pseudomonas aeruginosa infections are the underlying cause of morbidity and mortality in cystic fibrosis (CF). The endogenous lipid mediator resolvin (Rv) D1 is a potent regulator of resolution, and its roles, actions, and therapeutic potential in CF are of interest. Here, we investigated actions and efficacy of RvD1 in preclinical models of cystic fibrosis. Cftr knockout mice with chronic P. aeruginosa lung infection were treated with RvD1 to assess differences in lung bacterial load, inflammation, and tissue damage. Cells from volunteers with CF were treated with RvD1 during ex vivo infection with P. aeruginosa, and effects on phagocytosis and inflammatory signaling were determined. In CF mice, RvD1 reduced bacterial burden, neutrophil infiltration, and histological signs of lung pathology, improving clinical scores of diseases. Mechanistically, RvD1 increased macrophage-mediated bacterial and leukocyte clearance in vivo. The clinical significance of these findings is supported by actions in primary leukocytes and epithelial cells from volunteers with CF where RvD1 enhanced P. aeruginosa phagocytosis and reduced genes and proteins associated to NF-κB activation and leukocyte infiltration. Concentration of RvD1 in sputum from patients with CF was also inversely correlated to those of cytokines and chemokines involved in CF lung pathology. These findings demonstrate efficacy of RvD1 in enhancing resolution of lung inflammation and infections and provide proof of concept for its potential as a prototypic novel pro-resolutive therapeutic approach for CF.

WITHDRAWN: The Atlas of Inflammation Resolution (AIR).

The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.mam.2020.100894. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

The Atlas of Inflammation Resolution (AIR).

Acute inflammation is a protective reaction by the immune system in response to invading pathogens or tissue damage. Ideally, the response should be localized, self-limited, and returning to homeostasis. If not resolved, acute inflammation can result in organ pathologies leading to chronic inflammatory phenotypes. Acute inflammation and inflammation resolution are complex coordinated processes, involving a number of cell types, interacting in space and time. The biomolecular complexity and the fact that several biomedical fields are involved, make a multi- and interdisciplinary approach necessary. The Atlas of Inflammation Resolution (AIR) is a web-based resource capturing an essential part of the state-of-the-art in acute inflammation and inflammation resolution research. The AIR provides an interface for users to search thousands of interactions, arranged in inter-connected multi-layers of process diagrams, covering a wide range of clinically relevant phenotypes. By mapping experimental data onto the AIR, it can be used to elucidate drug action as well as molecular mechanisms underlying different disease phenotypes. For the visualization and exploration of information, the AIR uses the Minerva platform, which is a well-established tool for the presentation of disease maps. The molecular details of the AIR are encoded using international standards. The AIR was created as a freely accessible resource, supporting research and education in the fields of acute inflammation and inflammation resolution. The AIR connects research communities, facilitates clinical decision making, and supports research scientists in the formulation and validation of hypotheses. The AIR is accessible through https://air.bio.informatik.uni-rostock.de.

Methylcitrate synthase from Aspergillus fumigatus is essential for manifestation of invasive aspergillosis.

Invasive aspergillosis is a life-threatening disease mainly caused by the fungus Aspergillus fumigatus. In immunocompromised individuals conidia are not efficiently inactivated, which can end in invasive fungal growth. However, the metabolic requirements of the fungus are hardly known. Earlier investigations revealed an accumulation of toxic propionyl-CoA in a methylcitrate synthase mutant, when grown on propionyl-CoA-generating carbon sources. During invasive growth propionyl-CoA could derive from proteins, which are released from infected host tissues. We therefore assumed that a methylcitrate synthase mutant might display an attenuated virulence. Here we show that the addition of propionate to cell culture medium enhanced the ability of alveolar macrophages to kill methylcitrate synthase mutant but not wild-type conidia. When tested in a murine infection model, the methylcitrate synthase mutant displayed attenuated virulence and, furthermore, was cleared from tissues when mice survived the first phase of acute infection. The amplification of cDNA from infected mouse lungs confirmed the transcription of the methylcitrate synthase gene during invasion, which leads to the suggestion that amino acids indeed serve as growth-supporting nutrients during invasive growth of A. fumigatus. Thus, blocking of methylcitrate synthase activity abrogates fungal growth and provides a suitable target for new antifungals.

n-3 and n-6 polyunsaturated fatty acids induce the expression of COX-2 via PPARgamma activation in human keratinocyte HaCaT cells.

Polyunsaturated fatty acids (PUFA) n-3 inhibit inflammation, in vivo and in vitro in keratinocytes. We examined in HaCaT keratinocyte cell line whether eicosapentaenoic acid (EPA) a n-3 PUFA, gamma-linoleic acid (GLA) a n-6 PUFA, and arachidic acid a saturated fatty acid, modulate expression of cyclooxygenase-2 (COX-2), an enzyme pivotal to skin inflammation and reparation. We demonstrate that only treatment of HaCaT with GLA and EPA or a PPARgamma ligand (roziglitazone), induced COX-2 expression (protein and mRNA). Moreover stimulation of COX-2 promoter activity was increased by those PUFAs or rosiglitazone. The inhibitory effects of GW9662 and T0070907 (PPARgamma antagonists), on COX-2 expression and on stimulation of COX-2 promoter activity by EPA and GLA suggest that PPARgamma is implicated in COX-2 induction. Finally, PLA2 inhibitor methyl arachidonyl fluorophosphonate blocked the PUFA effects on COX-2 induction, promoter activity and arachidonic acid mobilization suggesting involvement of AA metabolites in PPAR activation. These findings demonstrate that n-3 and n-6 PUFA increased PPARgamma activity is necessary for the COX-2 induction in HaCaT human keratinocyte cells. Given the anti-inflammatory properties of EPA, we suggest that induction of COX-2 in keratinocytes may be important in the anti-inflammatory and protective mechanism of action of PUFAs n-3 or n-6.

Polyunsaturated fatty acid metabolism signature in ischemia differs from reperfusion in mouse intestine.

Polyunsaturated fatty acid (PUFA) metabolites are bioactive autoacoids that play an important role in the pathogenesis of a vast number of pathologies, including gut diseases. The induction and the resolution of inflammation depend on PUFA metabolic pathways that are favored. Therefore, understanding the profile of n-6 (eicosanoids)/n-3 (docosanoids) PUFA-derived metabolites appear to be as important as gene or protein array approaches, to uncover the molecules potentially implicated in inflammatory diseases. Using high sensitivity liquid chromatography tandem mass spectrometry, we characterized the tissue profile of PUFA metabolites in an experimental model of murine intestinal ischemia reperfusion. We identified temporal and quantitative differences in PUFA metabolite production, which correlated with inflammatory damage. Analysis revealed that early ischemia induces both pro-inflammatory and anti-inflammatory eicosanoid production. Primarily, LOX- (5/15/12/8-HETE, LTB4, LxA4) and CYP- (5, 6-EET) metabolites were produced upon ischemia, but also PGE3, and PDx. This suggests that different lipids simultaneously play a role in the induction and counterbalance of ischemic inflammatory response from its onset. COX-derived metabolites were more present from 2 to 5 hours after reperfusion, fitting with the concomitant inflammatory peaks. All metabolites were decreased 48 hours post-reperfusion except for to the pro-resolving RvE precursor 18-HEPE and the PPAR-Î³αµµα agonist, 15d-PGJ2. Data obtained through the pharmacological blockade of transient receptor potential vanilloid-4, which can be activated by 5, 6-EET, revealed that the endogenous activation of this receptor modulates post-ischemic intestinal inflammation. Altogether, these results demonstrate that different lipid pathways are involved in intestinal ischemia-reperfusion processes. Some metabolites, which expression is severely changed upon intestinal ischemia-reperfusion could provide novel targets and may facilitate the development of new pharmacological treatments.

Relevance of the cyclophosphamide-induced cystitis model for pharmacological studies targeting inflammation and pain of the bladder.

This work aimed at establishing the relevance of using the in vivo model of cyclophosphamide (CYP)-induced bladder inflammation in rats for in vivo pharmacological studies. Specifically, we measured visceral nociception, identified key inflammatory mediators and evaluated the effects of relevant pharmacological treatments. Cystitis was induced in female rats by a single CYP injection. Sensitivity of the lower abdomen to von Frey mechanical stimulation was determined as a nociceptive parameter. Bladders were assessed for weight, wall thickness and macroscopic damage. Inflammatory mediators were quantified in bladders and urines. The effects of aspirin, ibuprofen and morphine were investigated on all these parameters. A single CYP injection increased nociceptive scores and decreased nociceptive threshold in response to mechanical stimuli between 1 and 4h post-administration. Increased bladder weight and wall thickness were associated with edema and hemorrhage. Bladder levels of IL-1ß, IL-6, MCP-1 and VCAM, and urinary levels of PGE2 were increased. In contrast, a decrease in the urinary metabolites, indoxyl sulfate and pantothenic acid, was observed. Aspirin, ibuprofen and morphine decreased CYP-induced referred visceral pain. Aspirin and ibuprofen also reversed the increased wall thickness, macroscopic damage and levels of IL-1ß, IL-6 and PGE2, and the decreased panthotenic acid levels. In contrast, morphine increased wall thickness, edema, hemorrhage, and bladder IL-6 and MCP-1 levels. This work presents a new and reliable method to evaluate visceral sensitivity in rats, and new relevant biomarkers identified in the bladder and urine to measure inflammation and pain parameters for in vivo pharmacological studies.

LC-MS/MS method for rapid and concomitant quantification of pro-inflammatory and pro-resolving polyunsaturated fatty acid metabolites.

Lipid autacoids derived from n-3/n-6 polyunsaturated fatty acids (PUFA) are some of the earliest signals triggered by an inflammatory reaction. They are acting also as essential regulators of numerous biological processes in physiological conditions. With regards to their importance, a robust and rapid procedure to quantify a large variety of PUFA metabolites, applicable to diverse biological components needed to be formulated. We have developed a simple methodology using liquid chromatography-tandem mass spectrometry allowing quantification of low-level of PUFA metabolites including bioactive mediators, inactive products and pathway biomarkers. Solid phase extraction was used for samples preparation with an extraction yield of 80% ranging from 65% to 98%. The method was optimized to obtain a rapid (8.5min) and accurate separation of 26 molecules, with a very high sensitivity of detection and analysis (0.6-155pg). When applied to biological samples, the method enabled characterization of eicosanoids and docosanoids production in epithelial cells or foam macrophages stimulated with LPS, in biological fluids and tissues from mouse models of peritonitis or infectious colitis. Our results demonstrate that this new method can be used in cultured cells, in fluids and in colonic tissues to quantify pro-inflammatory and pro-resolving PUFA metabolites mediators.

Opposite roles of STAT and PPARgamma in the induction of p21WAF1 expression by IL-13 in human peripheral blood monocytes.

The cyclin kinase inhibitor p21WAF1 is expressed in most, if not all, differentiated cells in the human body and represents an important regulator of cell cycle control and terminal differentiation in the monocyte/macrophage lineage. It has been reported in macrophage cell lines that p21WAF1 expression is sensitive to numerous molecules including cytokines, but nothing was known about p21WAF1 regulation in human peripheral blood monocytes in response to Th2 cytokines. We report here, that IL-13 increases p21WAF1 expression in human blood monocytes. This induction is a transcription-dependent event, leading to an increase in mRNA content. We show that the signalling pathway for IL-13-induced p21WAF1 expression may involve the IL-4R alpha and the IL-13R alpha1 chains, and the tyrosine and JAK2 kinases. Also, p21WAF1 plasmid-based gene activation only requires a minimal p21WAF1 promoter, containing a putative PPRE. Since IL-13 signalisation involves PPARgamma, we tested PPARgamma involvement in p21WAF1 gene activation by using metabolic inhibitors of arachidonic acid metabolism, or by restoring PPARgamma expression in a defective cell line. We found that inhibition of PPARgamma increases IL-13-induced p21WAF1 gene expression in these models. These data argue that IL-13 upregulates p21WAF1 expression in monocytes via JAK/STAT pathway, and that the activation of PPARgamma by this cytokine can counteract this induction.

Aspergillus fumigatus induces innate immune responses in alveolar macrophages through the MAPK pathway independently of TLR2 and TLR4.

Aspergillus fumigatus causes invasive aspergillosis in immunosuppressed patients. In the immunocompetent host, inhaled conidia are cleared by alveolar macrophages. The signaling pathways of the alveolar macrophage involved in the clearance of A. fumigatus are poorly understood. Therefore, we investigated the role of TLRs in the immune response against A. fumigatus and their contribution to the signaling events triggered in murine alveolar macrophages upon infection with A. fumigatus conidia. Specifically, we examined the MAPKs and NF-kappaB activation and cytokine signaling. Our investigations revealed that immunocompetent TLR2, TLR4, and MyD88 knockout mice were not more susceptible to invasive aspergillosis as compared with wild-type mice and that the in vitro phosphorylation of the MAPKs ERK and p38 was not affected in TLR2, TLR4, or MyD88 knockout mice following stimulation with conidia. In vivo experiments suggest that ERK was an essential MAPK in the defense against A. fumigatus, whereas the activation of NF-kappaB appeared to play only a secondary role. In conclusion, our findings demonstrate that TLR2/4 recognition and MyD88 signaling are dispensable for the clearance of A. fumigatus under immunocompetent situations. Furthermore, our data stress the important role of ERK activation in innate immunity to A. fumigatus.

Infection of HepG2 cells with recombinant adenovirus encoding the HCV core protein induces p21(WAF1) down-regulation -- effect of transforming growth factor beta.

BACKGROUND/AIMS: Chronic infection with hepatitis C virus leads to liver cirrhosis and hepatocellular carcinoma. Hepatocellular carcinoma is sometimes associated with p53 dysfunction and decreased p21(WAF1) expression. The p21(WAF1) gene is a major target of p53, and p21(WAF1) protein regulates the activities of cyclin/CDK complexes involved in cell cycle control and tumor formation. Because core protein has oncogenic properties, we investigated the expression of p21(WAF1) following core expression. METHODS: We analyzed by Western blot, Northern blot and transfection the expression of p21(WAF1) in HepG2 cell line under transient expression of Hepatitis C core protein by recombinant-adenoviral infection. RESULTS AND DISCUSSION: Infection of HepG2 with core-encoding viruses induced the down-regulation of p21(WAF1) expression. This effect is due to a decrease in the p21(WAF1) gene transcription and of the p21(WAF1) protein half-life. These results support a role for Hepatitis C virus core protein in cell transformation. We also found also that the transforming growth factor beta can counteract the core-induced p21(WAF1) down-regulation. The antagonist effect of TGF beta, or of other molecules, on p21(WAF1) expression may be of particular interest for the treatment of HCV-positive hepatocellular carcinoma.

PPARgamma promotes mannose receptor gene expression in murine macrophages and contributes to the induction of this receptor by IL-13.

Macrophage mannose receptor (MMR) is an important component of the innate immune system implicated in host defense against microbial infections such as candidiasis and in antigen presentation. We demonstrate here that the MMR expression is induced in mouse peritoneal macrophages following exposure to PPARgamma ligands or to interleukine-13 (IL-13) via a PPARgamma signaling pathway. Ligand activation of the PPARgamma in macrophages promotes uptake, killing of Candida albicans, and reactive oxygen intermediates production triggered by the yeasts through MMR overexpression. We also show that MMR induction by IL-13 via PPARgamma is dependent on phopholipase A2 activation and that IL-13 induces 15d-PGJ2 production and nuclear localization. These results reveal a novel signaling pathway controlling the MMR surface expression and suggest that endogenous PPARgamma ligand produced by phospholipase A2 activation may be an important regulator of MMR expression by IL-13.