Metabolic correction in microglia derived from Sandhoff disease model mice

Sandhoff disease is an autosomal recessive lysosomal storage disease caused by a defect of the beta-subunit gene (HEXB) associated with simultaneous deficiencies of beta-hexosaminidase A (HexA; alphabeta) and B (HexB; betabeta), and excessive accumulation of GM2 ganglioside (GM2) and oligosaccharides with N-acetylglucosamine (GlcNAc) residues at their non-reducing termini. Recent studies have shown the involvement of microglial activation in neuroinflammation and neurodegeneration of this disease. We isolated primary microglial cells from the neonatal brains of Sandhoff disease model mice (SD mice) produced by disruption of the murine Hex beta-subunit gene allele (Hexb-/-). The cells expressed microglial cell-specific ionized calcium binding adaptor molecule 1 (Iba1)-immunoreactivity (IR) and antigen recognized by Ricinus communis agglutinin lectin-120 (RCA120), but not glial fibrillary acidic protein (GFAP)-IR specific for astrocytes. They also demonstrated significant intracellular accumulation of GM2 and GlcNAc-oligosaccharides. We produced a lentiviral vector encoding for the murine Hex beta-subunit and transduced it into the microglia from SD mice with the recombinant lentivirus, causing elimination of the intracellularly accumulated GM2 and GlcNAc-oligosaccharides and secretion of Hex isozyme activities from the transduced SD microglial cells. Recomibinant HexA isozyme isolated from the conditioned medium of a Chinese hamster ovary (CHO) cell line simultaneously expressing the human HEXA (alpha-subunit) and HEXB genes was also found to be incorporated into the SD microglia via cell surface cation-independent mannose 6-phosphate receptor and mannose receptor to degrade the intracellularly accumulated GM2 and GlcNAc-oligosaccharides. These results suggest the therapeutic potential of recombinant lentivirus encoding the murine Hex beta-subunit and the human HexA isozyme (alphabeta heterodimer) for metabolic cross-correction in microglial cells involved in progressive neurodegeneration in SD mice.     

Prostaglandin E2 suppresses chemokine production in human macrophages through the EP4 receptor

Pro-inflammatory pathways participate in the pathogenesis of atherosclerosis. However, the role of endogenous anti-inflammatory pathways in atheroma has received much less attention. Therefore, using cDNA microarrays, we screened for genes regulated by prostaglandin E(2) (PGE(2)), a potential endogenous anti-inflammatory mediator, in lipopolysaccharide (LPS)-treated human macrophages (MPhi). PGE(2) (50 nm) attenuated LPS-induced mRNA and protein expression of chemokines including monocyte chemoattractant protein-1, interleukin-8, macrophage inflammatory protein-1alpha and -1beta, and interferon-inducible protein-10. PGE(2) also inhibited the tumor necrosis factor-alpha-, interferon-gamma-, and interleukin-1beta-mediated expression of these chemokines. In contrast to the case of MPhi, PGE(2) did not suppress chemokine expression in human endothelial and smooth muscle cells (SMC) treated with LPS and pro-inflammatory cytokines. To assess the potential paracrine effect of endogenous PGE(2) on macrophage-derived chemokine production, we co-cultured MPhi with SMC in the presence of LPS. In these co-cultures, cyclooxygenase-2-dependent PGE(2) production exceeded that in the mono-cultures, and MIP-1beta declined significantly compared with MPhi cultured without SMC. We further documented prominent expression of the PGE(2) receptor EP4 in MPhi in both culture and human atheroma. Moreover, a selective EP4 antagonist completely reversed PGE(2)-mediated suppression of chemokine production. Thus, endogenous PGE(2) may modulate inflammation during atherogenesis and other inflammatory diseases by suppressing macrophage-derived chemokine production via the EP4 receptor.     

Prostaglandin E2 up-regulates macrophage-derived chemokine production but suppresses IFN-inducible protein-10 production by APC

PGE(2) has been known to suppress Th1 responses. We studied the role of PGE(2) in two representative chemokines, macrophage-derived chemokine (MDC) and IFN-inducible protein-10, production by LPS- or CD40-stimulated spleen cells. The production of MDC, one of the ligands for CCR4 preferentially expressed on Th2, was enhanced in nonstimulated, LPS-, CD40-, or CD3-stimulated spleen cells by the pretreatment with PGE(2), while the production of IFN-inducible protein-10, a representative ligand for CXC chemokine receptor 3 expressed on Th1, was suppressed. MDC production was also enhanced by IL-4, IL-5, and intracellular cAMP-elevating agents such as dibutyryl cAMP and 3-isobutyl-1-methylxanthine, and the effect of IL-4, IL-5, and PGE(2) was additive. However, the pretreatment with IL-6, IL-10, or TGF-beta, or the neutralization of IFN-gamma or IL-12 had no effect on MDC production. B cells, macrophages, and dendritic cells were main producers of MDC, while T cells produced only a small amount of MDC. MDC production by B cells was equally stimulated by LPS and anti-CD40 Ab, while that by macrophages and dendritic cells was more markedly stimulated by anti-CD40 Ab, and PGE(2) further enhanced MDC production by these stimulated cells. These results indicate that PGE(2) regulates Th1/Th2-related chemokine production by B cells, macrophages, and dendritic cells, and that this is a new function of PGE(2) for the regulation of Th2 immune responses at the induction and activation stages.     

Abnormal production of macrophage inflammatory protein-1α by microglial cell lines derived from neonatal brains of Sandhoff disease model mice

Sandhoff disease (SD) is a lysosomal β-hexosaminidase deficiency involving excessive accumulation of undegraded substrates, including terminal N -acetylglucosamine-oligosaccharides and GM2 ganglioside, and progressive neurodegeneration. Our previous study demonstrated remarkable induction of macrophage inflammatory factor-1α (MIP-1α) in microglia in the brains of SD model mice as a putative pathogenic factor for SD via microglia-mediated neuroinflammation. In this study, we established microglial cell lines (WT- and SD-Mg) from wild-type and SD mice, and first demonstrated the enhanced production of MIP-1α in SD-Mg. Inhibitors of protein kinase C (PKC) and Akt reduced the production of MIP-1α by SD-Mg. Elevated activation of Akt and partial translocation of PKC isozymes (α, βI, βII, and δ) from the cytoplasm to the membrane in SD-Mg were also revealed by means of immunoblotting. Furthermore, it was demonstrated that intracellular extracellular signal-regulated kinase, c-Jun N-terminal kinase, and phospholipase C (PLC), but not phosphoinositide 3-kinase, should contribute to the induction of MIP-1α in SD-Mg, and that PLC could independently regulate the activation of both PKC and Akt. We proposed here that the deregulated activation of PLC should cause the enhanced MIP-1α production via plural signaling pathways mediated by PKC and Akt, followed by extracellular signal-regulated kinase and c-Jun N-terminal kinase, in SD-Mg.     

Activation of BV2 microglia by lipopolysaccharide triggers an inflammatory reaction in PC12 cell apoptosis through a toll-like receptor 4-dependent pathway

Microglia play an important role in neuronal protection and damage. However, the molecular and cellular relationship between microglia and neurons is unclear. We carried out a prospective study to detect that activation of BV2 microglia induced PC12 cell apoptosis in vitro through the TLR4/adapter protein myeloid differentiation factor 88 (MyD88)/nuclear factor-κB (NF-κB) signaling pathway. BV2 microglia were treated with different concentrations of LPS for 24 h. Western blot was utilized to detect the expression of TLR4 and the downstream signaling pathway. The level of inflammatory mediator was quantified using a specific ELISA kit. The supernatant of 10 μg/ml LPS-treated BV2 cells was used as conditioned medium (CM). PC12 cells were co-culture with CM for 24 h. Cell viability was determined by MTT assay and cell apoptosis was tested by flow cytometry. BV2 microglia were treated with 10, 20, or 30 μg/ml LPS for 24 h. The expression of TLR4, MyD88, and NF-κB significantly increased. When PC12 cells were co-cultured with CM for 24 h, cell viability decreased. CM up-regulated the Bax level and down-regulated the Bcl-2 protein level in PC12 cells. PC12 cells pretreated with interleukin-1 receptor antagonist (IL-1RA) for 30 min, significantly alleviated CM-induced PC12 cell apoptosis. These results suggest that BV2 microglia activated by LPS triggered TLR4/MyD88/NF-κB signaling pathway that induced the release of IL-1β and could participate in the PC12 cells injury.     

Ganoderma lucidum extract protects dopaminergic neurons through inhibiting the production of inflammatory mediators by activated microglia

Abundant evidence has suggested that neuroinflammation participates in the pathogenesis of Parkinson's disease (PD). The emerging evidence has supported that microglia may play key roles in the progressive neurodegeneration in PD and might be a promising therapeutic target. Ganoderma lucidum (GL), a traditional Chinese medicinal herb, has been shown potential neuroprotective effect in our clinical trials that lead us to speculate that it might possess potent anti-inflammatory and immunomodulating properties. To test this hypothesis, the present study investigated the potential neuroprotective effect of GL and underlying mechanism through inhibiting microglial activation using co-cultures of dopaminergic neurons and microglia. The cultures of microglia or MES23.5 cells alone or together were treated for 24 h with lipopolysaccharide (LPS, 0.25 μg/mL) as a positive control, GL extracts (50-400 μg/mL) or MES23.5 cell membrane fragments (150 μg/mL) were used in treatment groups. Microglia activation, microglia-derived harmful factors and [(3)H]dopamine ([(3)H]DA) uptake of MES23.5 cells were analyzed. The results showed that microglia were activated by LPS and MPP(+)-treated MES23.5 cell membrane fragments, respectively. Meanwhile, GL extracts significantly prevented the production of microglia-derived proinflammatory and cytotoxic factors, including nitric oxide, tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β), in a dose-dependent manner and down-regulated the TNF-α and IL-1β expressions on mRNA level. In addition, GL extracts antagonized the reduction of [(3)H]DA uptake induced by MPP(+) and microglial activation. In conclusion, these results suggest that GL may be a promising agent for the treatment of PD through anti-inflammation.     

Prostaglandin E2 regulates renal cell carcinoma invasion through the EP4 receptor-Rap GTPase signal transduction pathway

Prognosis for patients with early stage kidney cancer has improved, but the treatment options for patients with locally advanced disease and metastasis remain few. Understanding the molecular mechanisms that regulate invasion and metastasis is critical for developing successful therapies to treat these patients. Proinflammatory prostaglandin E(2) plays an important role in cancer initiation and progression via activation of cognate EP receptors that belong to the superfamily of G protein-coupled receptors. Here we report that prostaglandin E(2) promotes renal cancer cell invasion through a signal transduction pathway that encompasses EP4 and small GTPase Rap. Inactivation of Rap signaling with Rap1GAP, like inhibition of EP4 signaling with ligand antagonist or knockdown with shRNA, reduces the kidney cancer cell invasion. Human kidney cells evidence increased EP4 and decreased Rap1GAP expression levels in the malignant compared with benign samples. These results support the idea that targeted inhibition of EP4 signaling and restoration of Rap1GAP expression constitute a new strategy to control kidney cancer progression.     

Specific induction of macrophage inflammatory protein 1-alpha in glial cells of Sandhoff disease model mice associated with accumulation of N-acetylhexosaminyl glycoconjugates

Sandhoff disease is a lysosomal storage disease caused by simultaneous deficiencies of beta-hexosaminidase A (HexA; alphabeta) and B (HexB; betabeta), due to a primary defect of the beta-subunit gene (HEXB) associated with excessive accumulation of GM2 ganglioside (GM2) and oligosaccharides with N-acetylhexosamine residues at their non-reducing termini, and with neurosomatic manifestations. To elucidate the neuroinflammatory mechanisms involved in its pathogenesis, we analyzed the expression of chemokines in Sandhoff disease model mice (SD mice) produced by disruption of the murine Hex beta-subunit gene allele (Hexb-/-). We demonstrated that chemokine macrophage inflammatory protein-1 alpha (MIP-1alpha) was induced in brain regions, including the cerebral cortex, brain stem and cerebellum, of SD mice from an early stage of the pathogenesis but not in other systemic organs. On the other hand, little changes in other chemokine mRNAs, including those of RANTES (regulated upon activation, normal T expressed and secreted), MCP-1 (monocyte chemotactic protein-1), SLC (secondary lymphoid-tissue chemokine), fractalkine and SDF-1 (stromal derived factor-1), were detected. Significant up-regulation of MIP-1alpha mRNA and protein in the above-mentioned brain regions was observed in parallel with the accumulation of natural substrates of HexA and HexB. Immunohistochemical analysis revealed that MIP-1alpha-immunoreactivity (IR) in the above-mentioned brain regions of SD mice was co-localized in Iba1-IR-positive microglial cells and partly in glial fibrillary acidic protein (GFAP)-IR-positive astrocytes, in which marked accumulation of N-acetylglucosaminyl (GlcNAc)-oligosaccharides was observed from the presymptomatic stage of the disease. In contrast, little MIP-1alpha-IR was observed in neurons in which GM2 accumulated predominantly. These results suggest that specific induction of MIP-1alpha might coincide with the accumulation of GlcNAc-oligosaccharides due to a HexB deficiency in resident microglia and astrocytes in the brains of SD mice causing their activation and acceleration of the progressive neurodegeneration in SD mice.     

Prostaglandin E1 and prostaglandin I2 modulation of superoxide production by human neutrophils

15(S)-15-methyl-prostaglandin E1 and prostaglandin I2 rapidly and reversibly inhibit formyl-methionyl-leucyl-phenylalanine induced superoxide production by human neutrophils. In contrast, 15(S)-15-methyl-prostaglandin E1 and prostaglandin I2 did not alter the rate or the total amount of superoxide production by human neutrophils stimulated with either phorbol myristate acetate or arachidonic acid. These data suggest that the production of superoxide anion by human neutrophils may be mediated by at least two mechanisms, one regulated by prostaglandins and intracellular cyclic adenosine monophosphate levels and a second independent of prostaglandin modulation.     

Prostaglandin E2 selectively enhances the IgE-mediated production of IL-6 and granulocyte-macrophage colony-stimulating factor by mast cells through an EP1/EP3-dependent mechanism

PGE(2) is an endogenously synthesized inflammatory mediator that is over-produced in chronic inflammatory disorders such as allergic asthma. In this study, we investigated the regulatory effects of PGE(2) on mast cell degranulation and the production of cytokines relevant to allergic disease. Murine bone marrow-derived mast cells (BMMC) were treated with PGE(2) alone or in the context of IgE-mediated activation. PGE(2) treatment alone specifically enhanced IL-6 production, and neither induced nor inhibited degranulation and the release of other mast cell cytokines, including IL-4, IL-10, IFN-gamma, and GM-CSF. IgE/Ag-mediated activation of BMMC induced the secretion of IL-4, IL-6, and GM-CSF, and concurrent PGE(2) stimulation synergistically increased mast cell degranulation and IL-6 and GM-CSF, but not IL-4, production. A similar potentiation of degranulation and IL-6 production by PGE(2), in the context of IgE-directed activation, was observed in the well-established IL-3-dependent murine mast cell line, MC/9. RT-PCR analysis of unstimulated MC/9 cells revealed the expression of EP(1), EP(3), and EP(4) PGE receptor subtypes, including a novel splice variant of the EP(1) receptor. Pharmacological studies using PGE receptor subtype-selective analogs showed that the potentiation of IgE/Ag-induced degranulation and IL-6 production by PGE(2) is mediated through EP(1) and/or EP(3) receptors. Our results suggest that PGE(2) may profoundly alter the nature of the mast cell degranulation and cytokine responses at sites of allergic inflammation through an EP(1)/EP(3)-dependent mechanism.     

Loss of Setd2 associates with aberrant microRNA expression and contributes to inflammatory bowel disease progression in mice

Both SETD2-mediated H3K36me3 and miRNAs play critical epigenetic roles in inflammatory bowel disease (IBD) and involve in the dysfunctional intestinal barrier. However, little is known about cross-talk between these two types of regulators in IBD progression. We performed small RNA sequencing of Setd2 epithelium-specific knockout mice (Setd2^Vil-KO) and wild-type controls, both with DSS-induced colitis, and designed a framework for integrative analysis. Firstly, we integrated the downloaded ChIP-seq data with miRNA expression profiles and identified a significant intersection of pre-miRNA expression and H3K36me3 modification. A significant inverse correlation was detected between changes of H3K36me3 modification and expression of the 171 peak-covered miRNAs. We further integrated RNA-seq data with predicted miRNA targets to screen negatively regulated miRNA-mRNA pairs and found the H3K36me3-associated differentially expressed microRNAs significantly enriched in cell-cell junction and signaling pathways. Using network analysis, we identified ten hub miRNAs, among which six are H3K36me3-associated, suggesting therapeutic targets for IBD patients with SETD2-deficiency.     

Prostaglandin E2 enhancement of interferon-gamma production by antigen-stimulated type 1 helper T cells.

Prostaglandin E2 (PGE2) is a potent mediator generated in immune tissues by cyclooxygenation of arachidonic acid. PGE2 affects T cell functions through four homologous G protein-coupled receptors termed EP1R, EP2R, EP3R, and EP4R that differ in tissue distribution and signaling. Antigen-evoked secretion of interferon-gamma (IFN-gamma) by sperm whale myoglobin-specific Th1 cells of DBA/2 mouse I-Ed-restricted clones, that express EP3Rs and EP4Rs, was enhanced a maximum of 3-fold by 10(-10) to 10(-8) M PGE2 and 2.5-fold each for the EP1R/EP3R-directed agonist sulprostone (10(-8) and 10(-7) M) and for the EP4R/EP3R/EP2R agonist misoprostol (10(-9) M). Neither PGE2 nor the synthetic analogs affected secretion of IFN-gamma by PMA plus ionomycin-stimulated clones of Th1 cells. Antigen-evoked secretion of IFN-gamma by influenza hemagglutinin-specific mouse lymph node Th1 cells, that also express EP3Rs and EP4Rs, was increased a maximum of 12-fold by 10(-9) to 10(-8) M PGE2, 14-fold by 10(-9) M sulprostone, and 10-fold by 10(-9) M misoprostol. Production of IFN-gamma by either type of Th1 cell was not affected significantly by 10(-6) M PGE2 alone. The generation of IFN-gamma by antigen-stimulated Th1 cells thus is significantly enhanced by physiologically relevant concentrations of PGE2.     

Cyclooxygenase-2 and Prostaglandin E2 Signaling through Prostaglandin Receptor EP-2 Favor the Development of Myocarditis during Acute Trypanosoma cruzi Infection

Inflammation plays an important role in the pathophysiology of Chagas disease, caused by Trypanosoma cruzi. Prostanoids are regulators of homeostasis and inflammation and are produced mainly by myeloid cells, being cyclooxygenases, COX-1 and COX-2, the key enzymes in their biosynthesis from arachidonic acid (AA). Here, we have investigated the expression of enzymes involved in AA metabolism during T. cruzi infection. Our results show an increase in the expression of several of these enzymes in acute T. cruzi infected heart. Interestingly, COX-2 was expressed by CD68⁺ myeloid heart-infiltrating cells. In addition, infiltrating myeloid CD11b⁺Ly6G^- cells purified from infected heart tissue express COX-2 and produce prostaglandin E₂ (PGE₂) ex vivo. T. cruzi infections in COX-2 or PGE₂-dependent prostaglandin receptor EP-2 deficient mice indicate that both, COX-2 and EP-2 signaling contribute significantly to the heart leukocyte infiltration and to the release of chemokines and inflammatory cytokines in the heart of T. cruzi infected mice. In conclusion, COX-2 plays a detrimental role in acute Chagas disease myocarditis and points to COX-2 as a potential target for immune intervention.     

Prostaglandin E2 induces degranulation-independent production of vascular endothelial growth factor by human mast cells

Mast cells accumulate in large numbers at angiogenic sites, where they have been shown to express a number of proangiogenic factors, including vascular endothelial growth factor (VEGF-A). PGE(2) is known to strongly promote angiogenesis and is found in increased levels at sites of chronic inflammation and around solid tumors. The expression pattern of VEGF and the regulation of VEGF-A by PGE(2) were examined in cord blood-derived human mast cells (CBMC). CBMC expressed mRNA for five isoforms of VEGF-A and other members of the VEGF family (VEGF-B, VEGF-C, and VEGF-D) with strong expression of the most potent secretory isoforms. PGE(2) was a very strong inducer of VEGF-A(121/165) production by CBMC and also elevated VEGF-A mRNA expression. The amount of VEGF-A(121/165) protein production induced by PGE(2) was 4-fold greater than that induced by IgE-mediated activation of CBMC. Moreover, the response to PGE(2) as well as to other cAMP-elevating agents such as forskolin and salbutamol was observed under conditions that were not associated with mast cell degranulation. CBMC expressed substantial levels of the EP(2) receptor, but not the EP(4) receptor, when examined by flow cytometry. In contrast to other reported PGE(2)-mediated effects on mast cells, VEGF-A(121/165) production occurred via activation of the EP(2) receptor. These data suggest a role for human mast cells as a potent source of VEGF(121/165) in the absence of degranulation, and may provide new opportunities to regulate angiogenesis at mast cell-rich sites.     

Prostaglandin E2 production by renal inner medullary tissue slices: effect of metabolic inhibitors

Increasing oxygen from 5 to 95% has previously been shown to increase prostaglandin (PG) production in renal inner medullary slices. The possible role of oxidative phosphorylation in this process was investigated. The oxidative phosphorylation inhibitors, dinitrophenol (DNP), oligomycin, and cyanide were evaluted for their effects on PGE2 production and ATP levels. None of the inhibitors affected PGE2 synthesis, although they lowered ATP levels at the concentrations tested. In contrast, incubation of inner medullary tissue slices with 0% oxygen resulted in decreases both in PGE2 and ATP levels. This suggests that the effect of oxygen on prostaglandin synthesis may be due to substrate limiting effects rather than an effect on oxidative phosphorylation. When 22 mM 2-deoxyglucose was added to the incubation medium or when glucose was omitted, PGE2 levels increased. Sodium fluoride, presumably acting as a glycolytic inhibitor, increased PGE2 levels, with a maximal effect at 10 mM. ATP levels were 37% of control values with 20 mM NaF. This indicates that glucose may inhibit prostaglandin synthesis. These results indicate that oxygen (substrate) availability can limit inner medullary PGE2 production. In view of the low pO2 in the inner medulla, especially during antidiuresis, oxygen can potentially regulate prostaglandin production in this tissue.     

Prostaglandin E2-dependent enhancement of tissue inhibitors of metalloproteinases-1 production limits dendritic cell migration through extracellular matrix

Dendritic cell (DC) migration is crucial for the initiation of immune responses. The balance between metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) has been shown to modulate DC migration. PGE2, which is overproduced in a wide variety of human malignancies, has been implicated in MMP and TIMP regulation in various cells, including monocytes. In the present study, we hypothesized that tumor-derived PGE2 would affect DC migratory capacity through the extracellular matrix (ECM) by altering MMP and TIMP balance. Treatment of monocyte-derived immature DC with exogenous PGE2 induced TIMP-1 secretion but not MMP-9 production and was correlated with reduced DC migration through ECM. Because recombinant TIMP-1 replicated PGE2 inhibition of DC migration while anti-TIMP-1 neutralizing Ab reversed it, we conclude that PGE2-mediated induction of TIMP-1 was responsible for the reduced migration of PGE2-treated DC. Similarly, DC cultured for 48 h in supernatants from cyclooxygenase-2 overexpressing lung cancer cells that secrete high levels of PGE2, exhibited decreased migration through ECM. Finally, analysis of E prostanoid receptor expression and their selective inhibition revealed that the enhanced TIMP-1 secretion in PGE2-treated DC was mediated predominantly by the E prostanoid receptor 2. These findings indicate that PGE2-dependent enhancement of TIMP-1 production causes reduced migration of DC through ECM.     

Candida albicans induces cyclo-oxygenase 2 expression and prostaglandin E2 production in synovial fibroblasts through an extracellular-regulated kinase 1/2 dependent pathway

Introduction

Synovial cells are potential sources of inflammatory mediators in bacterial-induced arthritis but their involvement in the inflammatory response to Candida albicans-induced septic arthritis is largely unknown.

Methods

Primary cultures of rat synovial fibroblasts were infected with C. albicans (ATCC90028). Immunocytochemistry, western blotting, and RT-PCR were performed to assess cyclo-oxygenase 2 induction. Phosphorylation of extracellular-regulated kinase (ERK1/2) following infection in the absence or presence of U0126 was assessed by western blotting whilst prostaglandin E2 production was measured by ELISA. Nuclear factor κB (NFκB) translocation was evaluated by an electrophoretic mobility shift assay.

Results

Infection of synovial fibroblasts with C. albicans resulted in cyclo-oxygenase 2 expression and prostaglandin E2 production. Cyclo-oxygenase 2 expression and prostaglandin E2 production was dependent upon extracellular-regulated kinase 1/2 phosphorylation, associated with activation of NFκB and significantly elevated in the presence of laminarin, an inhibitor of dectin-1 activity. Synovial fibroblasts adjacent to C. albicans hyphae aggregates appeared to be the major contributors to the increased levels of cyclo-oxygenase 2 and phosphorylated extracellular-regulated kinase 1/2.

Conclusions

C. albicans infection of synovial fibroblasts in vitro results in upregulation of cyclo-oxygenase 2 and prostaglandin E2 by mechanisms that may involve activation of extracellular-regulated kinase 1/2 and are associated with NFκB activation.