Aspirin inhibits Chlamydia pneumoniae-induced NF-kappa B activation, cyclo-oxygenase-2 expression and prostaglandin E2 synthesis and attenuates chlamydial growth

Aspirin triggers ferroptosis in hepatocellular carcinoma cells through restricting NF-κB p65-activated SLC7A11 transcription

A number of studies have shown that aspirin, as commonly prescribed drug, prevents the development of hepatocellular carcinoma (HCC). Ferroptosis as a dynamic tumor suppressor plays a vital role in hepatocarcinogenesis. In this study we investigated whether aspirin affected ferroptosis in liver cancer cells. RNA-seq analysis revealed that aspirin up-regulated 4 ferroptosis-related drivers and down-regulated 5 ferroptosis-related suppressors in aspirin-treated HepG2 cells. Treatment with aspirin (4 mM) induced remarkable ferroptosis in HepG2 and Huh7 cells, which was enhanced by the ferroptosis inducer erastin (10 μM). We demonstrated that NF-κB p65 restricted ferroptosis in HepG2 and Huh7 cells through directly binding to the core region of SLC7A11 promoter and activating the transcription of ferroptosis inhibitor SLC7A11, whereas aspirin induced ferroptosis through inhibiting NF-κB p65-activated SLC7A11 transcription. Overexpression of p65 rescued HepG2 and Huh7 cells from aspirin-induced ferroptosis. HCC patients with high expression levels of SLC7A11 and p65 presented lower survival rate. Functionally, NF-κB p65 blocked the aspirin-induced ferroptosis in vitro and in vivo, which was attenuated by erastin. We conclude that aspirin triggers ferroptosis by restricting NF-κB-activated SLC7A11 transcription to suppress the growth of HCC. These results provide a new insight into the mechanism by which aspirin regulates ferroptosis in hepatocarcinogenesis. A combination of aspirin and ferroptosis inducer may provide a potential strategy for the treatment of HCC in clinic.

Aspirin and Infection: A Narrative Review

Acetylsalicylic acid (ASA) is one of the most commonly used drugs in the world. It derives from the extract of white willow bark, whose therapeutic potential was known in Egypt since 1534 BC. ASA's pharmacological effects are historically considered secondary to its anti-inflammatory, platelet-inhibiting properties; however, human studies demonstrating a pro-inflammatory effect of ASA exist. It is likely that we are aware of only part of ASA's mechanisms of action; moreover, the clinical effect is largely dependent on dosages. During the past few decades, evidence of the anti-infective properties of ASA has emerged. We performed a review of such research in order to provide a comprehensive overview of ASA and viral, bacterial, fungal and parasitic infections, as well as ASA's antibiofilm properties.

Low-Dose Aspirin May Prevent Trophoblast Dysfunction in Women With Chlamydia Pneumoniae Infection

OBJECTIVE

Previously, we demonstrated that live Chlamydia pneumoniae (Cp) impaired extravillous trophoblast (EVT) viability and invasion and that Cp DNA was detected in placentas from cases with preeclampsia. We sought to elucidate whether (1) inactive forms of Cp also affect EVT function; (2) potential therapeutic interventions protect against the effects of Cp; and (3) anti-Cp antibodies are associated with preeclampsia.

METHODS

Human first-trimester EVTs were infected with ultraviolet light-inactivated Cp. Subgroups of EVTs were pretreated with low-dose acetyl-salicylic acid (ASA), dexamethasone, heparin, and indomethacin. We conducted functional assays after infection with inactivated Cp and measured interleukin 8 (IL8), C-reactive protein (CRP), heat shock protein 60 (HSP60), and tumor necrosis factor-α (TNFα) in culture media. We measured anti-Cp IgG serum levels from women who developed preeclampsia (N = 105) and controls (N = 121).

RESULTS

Inactivated Cp reduced EVT invasion when compared to noninfected cells (P < .00001) without adversely affecting cell viability. Increased levels of IL8, CRP, HSP60, and TNFα were detected in EVTs infected with inactivated Cp compared to noninfected cells (P < .0001). Only pretreatment with low-dose ASA prevented reduced EVT invasion and decreased release of inflammatory mediators (P < .01). Elevated anti-Cp IgG antibodies were more prevalent in serum from cases with preeclampsia compared to controls (67/105 vs 53/121; adjusted P = .013); elevated IgG correlated significantly with elevated serum CRP and elevated soluble fms-like tyrosine kinase-1-placental growth factor ratio.

CONCLUSION

Inactivated Cp induces decreased EVT invasion and a proinflammatory response; these effects were abrogated by pretreatment with low-dose ASA. Our results suggest an association between Cp infection, trophoblast dysfunction, and preeclampsia.

Chlamydia pneumoniae heat shock protein 60 enhances expression of ERK, TLR-4 and IL-8 in atheromatous plaques of coronary artery disease patients

Chlamydia pneumoniae heat shock protein (cHSP) 60 is produced during chronic chlamydial infection and activate innate immune and inflammatory responses thereby contributing to atherogenesis. However, to date there is no apparent signaling cascade delineated in human atherosclerotic plaques in C. pneumoniae positive coronary artery disease (CAD) patients. Atherosclerotic plaques were obtained from 40 CAD patients (28 men, 12 women) attending Department of Cardio Thoracic and Vascular Surgery Safdarjung Hospital, New Delhi. Atherosclerotic plaques were used for gene expression studies at RNA level by real-time PCR and to study expression of ERK1/2, JNK1/2, NF-kB, IkkB and MCP-1 at protein level by immunoblotting. Significantly higher (p < 0.001) RNA expression was found for IL-8, TLR-2/4, TGF-β, ICAM1, VCAM1 and MAPKinase genes, whereas significantly lower (p < 0.001) RNA expression for SMAD4, IkkB, BRCA1 and IL-10 was detected in cHSP60-positive atheromatous plaque of CAD patients. Moreover, at proteins level pERK1/2 (p = 0.05), NF-kB (p = 0.017), MCP-1 (p = 0.011) was higher and IkkB expression was lower (p = 0.038) in cHSP60-positive atheromatous plaque of CAD patients. This study by using human atheromatous plaques at RNA and protein levels demonstrated higher expression of TLR-2/4, IL-8, ICAM1, VCAM1, ERK1/2 and NF-kB in cHSP60-positive CAD patients.

The inhibitory effects of Gelam honey and its extracts on nitric oxide and prostaglandin E(2) in inflammatory tissues

We investigated the effects of honey and its methanol and ethyl acetate extracts on inflammation in animal models. Rats' paws were induced with carrageenan in the non-immune inflammatory and nociceptive model, and lipopolysaccharide (LPS) in the immune inflammatory model. Honey and its extracts were able to inhibit edema and pain in inflammatory tissues as well as showing potent inhibitory activities against NO and PGE(2) in both models. The decrease in edema and pain correlates with the inhibition of NO and PGE(2). Phenolic compounds have been implicated in the inhibitory activities. Honey is potentially useful in the treatment of inflammatory conditions.

15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is up-regulated by flurbiprofen and other non-steroidal anti-inflammatory drugs in human colon cancer HT29 cells

Non-steroidal anti-inflammatory drugs (NSAIDs) are known to inhibit prostaglandin synthetic enzyme, cyclooxygenases (COXs), as well as to exhibit anti-tumor activity although at much higher concentrations. 15-Hydroxyprostaglandin dehyrogenase (15-PGDH), a key prostaglandin catabolic enzyme, was recently shown to be a tumor suppressor. Effects of NSAIDs on 15-PGDH expression were therefore examined. Flurbiprofen and several other NSAIDs were found to induce 15-PGDH expression in human colon cancer HT29 cells. Flurbiprofen, the most active one, was also shown to induce 15-PGDH expression in other types of cancer cells. Induction of 15-PGDH expression appeared to occur at the stage of mRNA as levels of 15-PGDH mRNA were increased by flurbiprofen in HT29 cells. Levels of 15-PGDH were also found to be regulated at the stage of protein turnover. MEK inhibitors, PD98059 and U-0126, which inhibited ERK phosphorylation were shown to elevate 15-PGDH levels very significantly. These inhibitors did not appear to alter 15-PGDH mRNA levels but down-regulate matrix metalloproteinase-9 (MMP-9). This protease was shown to degrade and inactivate 15-PGDH suggesting that elevation of 15-PGDH levels could be due to inhibition of MMP-9 expression by these inhibitors. Similarly, flurbiprofen was also demonstrated to inhibit ERK activation and to down-regulate MMP-9 expression. Furthermore, flurbiprofen was shown to induce the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1), an inhibitor of MMP-9. The turnover of 15-PGDH was found to prolong in the presence of flurbiprofen as compared to that in the absence of this drug. Taken together, these results indicate that flurbiprofen up-regulates 15-PGDH by increasing the expression and decreasing the degradation of 15-PGDH in HT29 cells.

Inhibition of lymphocyte CD3 expression by Chlamydophila pneumoniae infection

Since lymphocytes are a major immune cell besides macrophages in the development of atherosclerosis, interaction between lymphocytes and Chlamydophila pneumoniae may contribute to the pathogenesis of chronic inflammatory diseases associated with C. pneumoniae. In this regard, we examined a possible alteration of CD3 expression of human lymphocyte Molt-4 cells by C. pneumoniae infection. The expression levels of CD3 molecules of lymphocyte Molt-4 cells were significantly decreased by C. pneumoniae infection. In contrast, heat-killed C. pneumoniae as well as mock (cell lysates) did not cause any alteration of CD3 expression of the cells. Treatment of the infected cells with NS-398 (cyclo-oxyganase-2 inhibitor) or AH-23848 (EP(4) prostanoid receptor antagonist) abolished the inhibition of CD3 expression. The enhanced prostaglandin E(2) (PGE(2)) productions in the culture supernatants of infected cells were confirmed by competitive enzyme-immunosorbent assay (ELISA). C. pneumoniae infection of enriched lymphocytes from human peripheral blood mononuclear cells also induced a decrease of CD3 expression. Thus, C. pneumoniae infection of lymphocytes induces a decrease of CD3 expression mediated by possibly PGE(2) production.

Genome-wide analysis of Chlamydophila pneumoniae gene expression at the late stage of infection

Chlamydophila pneumoniae, an obligate intracellular eubacterium, changes its form from a vegetative reticulate body into an infectious elementary body during the late stage of its infection cycle. Comprehension of the molecular events in the morphological change is important to understand the switching mechanism between acute and chronic infection, which is deemed to relate to the pathogenesis of atherosclerosis. Herein, we have attempted to screen genes expressed in the late stage with a genome-wide DNA microarray, resulting in nomination of 17 genes as the late-stage genes. Fourteen of the 17 genes and six other genes predicted as late-stage genes were confirmed to be up-regulated in the late stage with a quantitative reverse transcriptase–polymerase chain reaction. These 20 late-stage genes were classified into two groups by clustering analysis: ‘drastically induced’ and ‘moderately induced’ genes. Out of eight drastically induced genes, four contain σ²⁸ promoter-like sequences and the other four contain an upstream common sequence. It suggests that besides σ²⁸, there are certain up-regulatory mechanisms at the late stage, which may be involved in the chlamydial morphological change and thus pathogenesis.

Acetylbritannilactone suppresses lipopolysaccharide-induced vascular smooth muscle cell inflammatory response

To investigate the mechanism of action by which a new anti-inflammatory active compound, 1-O-acetylbritannilactone (ABL) isolated from Inula britannica-F., inhibits inflammatory responses in vascular smooth muscle cells (VSMCs). Enzyme immunoassay was used to measure the levels of prostandin E(2) (PGE(2)) production. Immunocytochemistry staining and Western blot analysis were performed to detect the nuclear translocation of nuclear factor-kappaB (NF-kappaB) p65 and the expression of IkappaB-alpha, pIkappaB-alpha and cyclooxygenase-2 (COX-2). Electrophoretic mobility shift assays (EMSA) were used to detect DNA-binding activity of NF-kappaB in VSMCs. ABL (5, 10, 20 micrommol/l) had several concentration-dependent effects, including inhibition of lipopolysaccharide (LPS)-induced PGE(2) production and COX-2 expression, and blockade of NF-kappaB activation and translocation. These effects were owing to reductions in IkappaB-alpha phosphorylation and degradation induced by LPS. In addition, ABL directly inhibited the binding of active NF-kappaB to specific DNA cis-element. These results indicate that ABL is a potent inhibitor of LPS-stimulated VSMC inflammatory responses through blockade of NF-kappaB activity and inhibition of inflammatory gene COX-2 expression.

No prognostic significance of chronic infection with Chlamydia pneumoniae in acute coronary syndromes: insights from the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial

BACKGROUND

Although relationships between chronic Chlamydia pneumoniae (Cpn) infection and the risk of coronary events in stable coronary artery disease patients have been reported, a similar link in acute coronary syndrome (ACS) patients has not been consistently observed.

METHODS

In a nested case-control substudy of the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial, 295 cases (30-day death/myocardial infarction [MI]) were matched by age, sex, baseline creatine kinase-myocardial kinase, and smoking status with 295 control subjects. To test the hypothesis on 1-year mortality, another subset (n = 276) was drawn from the 590-patient cohort; 138 patients who died at 1 year plus the matching controls who survived at 1 year. We measured Cpn IgG and IgA antibody titers in baseline serum with microimmunofluorescence. Conditional logistic regression was used to quantify the prognostic relevance seropositivity (IgG > or = 1:32; IgA > or = 1:16) and elevated titer levels.

RESULTS

The prevalence of Cpn IgG and IgA was similar between cases and controls (30-day death/MI: IgG, 80% vs 85%, P = .126; IgA, 45% vs 37%, P = .079), and were not statistically significant predictors of 30-day death/MI after baseline adjustment. Likewise, the 1-year death cohort had comparable proportions of Cpn IgG and IgA among cases and controls (86% vs 91% [P = .265] and 49% vs 43% [P = .334], respectively), and did not add prognostic value.

CONCLUSIONS

These findings are in concert with study results suggesting that chronic Cpn infection is not associated with 30-day death/MI or 1-year mortality in non-ST elevation ACS.

Bacterial clearance ofPseudomonas aeruginosa is enhanced by the inhibition of COX-2

Prostanoids generated by COX-2 are involved in the regulation of inflammation but their exact role in the innate immune response has not been defined. We investigated whether COX-2 is involved in host defense against Pseudomonas aeruginosa pneumonia. In vitro studies, in a macrophage cell line, showed that cytotoxic strain of P aeruginosa (PA103) induced significant COX-2 protein expression and enzymatic function. In vivo data showed that infection with PA103 increased COX-2 protein production in whole lung tissue compared to mice that were infected with mutant bacteria that lack ExoU (DeltaU) or ExoU and ExoT (DeltaUT). COX-2(-/-) mice had accentuated clearance of cytotoxic P. aeruginosa from the lungs. We further tested the effects of COX-2 products such as prostaglandin E(2) on the function of phagocytic cells. Our studies indicate that prostaglandin E(2) may be involved through interacting with the EP2 receptors in modulating the host response because treatment of macrophages with prostaglandin E(2) suppressed production of reactive oxygen species. Furthermore there was enhanced bacterial clearance in EP2 receptor(-/-) mice compared to the wild-type controls. Thus it is possible that inhibition of COX-2 or EP2 receptors could be an effective adjunctive treatment for severe or resistant P. aeruginosa pneumonia.

Infection of human endothelial cells with spotted Fever group rickettsiae stimulates cyclooxygenase 2 expression and release of vasoactive prostaglandins

Rickettsiae, a diverse group of obligately intracellular gram-negative bacteria, include etiologic agents of the spotted fever and typhus groups of diseases. Rocky Mountain spotted fever and boutonneuse fever, due to Rickettsia rickettsii and R. conorii, respectively, are characterized by widespread infection of the vascular endothelium, microvascular injury, and vasculitis. Cultured human endothelial cells (EC) are highly susceptible to infection and respond by altering the expression of adhesion molecules, regulatory cytokines, and the antioxidant enzyme heme oxygenase (HO). In the vasculature, HO regulates the cyclooxygenase (COX) enzymes, among which the inducible isozyme COX-2 facilitates the synthesis of prostaglandins (PGs). Using in vitro and ex vivo models of infection, we demonstrate here that R. rickettsii infection of human EC causes robust induction of COX-2 mRNA and protein expression but has no apparent effect on the constitutive COX-1 isoform. Cells infected with viable rickettsiae consistently displayed significantly increased secretion of 6-keto-PGF(1alpha) and PGE(2). R. rickettsii-induced COX-2 was sensitive to inhibitors of de novo transcription and the pyridinylimidazole-based compound SB 203580, suggesting that this transcriptional host cell response involves signaling through p38 mitogen-activated protein kinase. PG production by infected cells was abrogated by NS 398 (a selective COX-2 inhibitor) and indomethacin (a pan-COX inhibitor). Immunohistochemical staining of sections of infected umbilical cords and corresponding uninfected controls revealed comparatively more intense and abundant staining for COX-2 in infected endothelia. Induction of the endothelial COX-2 system and the resultant enhanced release of vasoactive PGs may contribute to the regulation of inflammatory responses and vascular permeability changes during spotted fever rickettsioses.

Atorvastatin reduces the expression of prostaglandin E2 receptors in human carotid atherosclerotic plaques and monocytic cells: potential implications for plaque stabilization

Prostaglandin E2 (PGE2), the product of cyclooxygenase-2 (COX-2) and prostaglandin E synthase-1 (mPGES-1), acts through its receptors (EPs) and induces matrix metalloproteinase (MMP) expression, which may favor the instability of atherosclerotic plaques. The effect of statins on EPs expression has not been previously studied. The aim of this study was to investigate the effect of atorvastatin (ATV, 80 mg/d, for one month) on EP expression in plaques and peripheral blood mononuclear cells (PBMC) of patients with carotid atherosclerosis. In addition, we studied the mechanisms by which statins could modulate EPs expression on cultured monocytic cells (THP-1) stimulated with proinflammatory cytokines (IL-1beta and TNF-alpha). Patients treated with atorvastatin showed reduced EP-1 (14 +/- 1.8% versus 26 +/- 2%; P < 0.01), EP-3 (10 +/- 1.5% versus 26 +/- 1.5%; P < 0.05), and EP-4 expression (10 +/- 4.1% versus 26.6 +/- 4.9%; P < 0.05) in atherosclerotic plaques (immunohistochemistry), and EP-3 and EP-4 mRNA expression in PBMC (real time PCR) in relation to non-treated patients. In cultured monocytic cells, atorvastatin (10 micromol/L) reduced EP-1/-3/-4 expression, along with COX-2, mPGES-1, MMP-9, and PGE2 levels elicited by IL-1beta and TNF-alpha. Similar results were noted with aspirin (100 micromol/L), dexamethasone (1 micromol/L), and the Rho kinase inhibitors Y-27632 and fasudil (10 micromol/L both). The effect of atorvastatin was reversed by mevalonate, farnesyl pyrophosphate, and geranylgeranyl pyrophosphate. On the whole, we have shown that atorvastatin reduces EPs expression in atherosclerotic plaques and blood mononuclear cells of patients with carotid stenosis and in cultured monocytic cells. The inhibition of EP receptors could explain, at least in part, some of the mechanisms by which statins could modulate the COX-2/mPGES-1 proinflammatory pathway and favor plaque stabilization in humans.

Potential Roles for Regulatory Oxygenases in Rickettsial Pathogenesis

Clinical and experimental evidence suggests an important role for oxidative stress and associated cellular defense mechanisms in the pathogenesis of vasculopathic rickettsioses. Our laboratory has reported that R. rickettsii infection of endothelial cells in vitro induces the expression of HO-1, the inducible isoform of the antioxidant defense enzyme heme oxygenase. HO-1 plays a critical role in maintaining the integrity of the vasculature and controls the functioning of the cyclooxygenase (COX) system. This study was undertaken to investigate the expression of COX and HO isozymes during in vitro infection of EC with two major representatives of spotted fever group Rickettsia species. The mRNA expression of COX-2 was significantly increased in endothelial cells infected with R. rickettsii and R. conorii, while that of COX-1 remained unaffected. Western blot analysis using total protein lysates from infected endothelial cells and corresponding uninfected controls further confirmed specific induction of COX-2 in response to infection. ELISA measurements on culture supernatants also suggested enhanced secretion of 6-keto PGF(1alpha) (stable hydrolysis product of PGI(2) and PGE(2). As a functional consequence of HO-1 upregulation, increased expression of the iron storage protein ferritin following R. rickettsii and R. conorii infection was also evident. Since products of HO-1 and COX-2 reactions govern a variety of physiologically important functions in the vasculature, further studies to define their regulation in the host cell should provide useful insights into the pathogenesis of rickettsial diseases.

Glucocorticoids increase in vitro and in vivo activities of antibiotics against Chlamydophila pneumoniae

The in vitro and in vivo antichlamydial activities of dexamethasone and beclomethasone alone and in combination with an antibiotic were tested. In vitro, dexamethasone and beclomethasone decreased the number of inclusion-forming units versus the control number (P < 0.001). The combination of glucocorticoids with azithromycin, telithromycin, or levofloxacin was more active than antibiotics used alone (P < 0.001). The combination, tested in a murine Chlamydophila pneumoniae infection model, produced similar results.

NF-kappaB activation during Rickettsia rickettsii infection of endothelial cells involves the activation of catalytic IkappaB kinases IKKalpha and IKKbeta and phosphorylation-proteolysis of the inhibitor protein IkappaBalpha

Rocky Mountain spotted fever, a systemic tick-borne illness caused by the obligate intracellular bacterium Rickettsia rickettsii, is associated with widespread infection of the vascular endothelium. R. rickettsii infection induces a biphasic pattern of the nuclear factor-kappaB (NF-kappaB) activation in cultured human endothelial cells (ECs), characterized by an early transient phase at 3 h and a late sustained phase evident at 18 to 24 h. To elucidate the underlying mechanisms, we investigated the expression of NF-kappaB subunits, p65 and p50, and IkappaB proteins, IkappaBalpha and IkappaBbeta. The transcript and protein levels of p50, p65, and IkappaBbeta remained relatively unchanged during the course of infection, but Ser-32 phosphorylation of IkappaBalpha at 3 h was significantly increased over the basal level in uninfected cells concomitant with a significant increase in the expression of IkappaBalpha mRNA. The level of IkappaBalpha mRNA gradually returned toward baseline, whereas that of total IkappaBalpha protein remained lower than the corresponding controls. The activities of IKKalpha and IKKbeta, the catalytic subunits of IkappaB kinase (IKK) complex, as measured by in vitro kinase assays with immunoprecipitates from uninfected and R. rickettsii-infected ECs, revealed significant increases at 2 h after infection. The activation of IKK and early phase of NF-kappaB response were inhibited by heat treatment and completely abolished by formalin fixation of rickettsiae. The IKK inhibitors parthenolide and aspirin blocked the activities of infection-induced IKKalpha and IKKbeta, leading to attenuation of nuclear translocation of NF-kappaB. Also, increased activity of IKKalpha was evident later during the infection, coinciding with the late phase of NF-kappaB activation. Thus, activation of catalytic components of the IKK complex represents an important upstream signaling event in the pathway for R. rickettsii-induced NF-kappaB activation. Since NF-kappaB is a critical regulator of inflammatory genes and prevents host cell death during infection via antiapoptotic functions, selective inhibition of IKK may provide a potential target for enhanced clearance of rickettsiae and an effective strategy to reduce inflammatory damage to the host during rickettsial infections.

Production of prostaglandin E2 in monocytes stimulated in vitro by Chlamydia trachomatis, Chlamydophila pneumoniae, and Mycoplasma fermentans

Chlamydia trachomatis (CT) as well as Chlamydophila pneumoniae (CP) cause chronic inflammatory diseases in humans. Persistently infected monocytes are involved in the pathogenesis by inducing mediators of inflammation. An in vitro system of chlamydial persistence in human peripheral blood monocytes (HPBM) was used to investigate prostaglandin E(2) (PGE(2)) production and the expression of the key enzyme for prostaglandin production, cyclooxygenase-2 (COX-2). PGE(2) production was determined by PGE(2)-ELISA of HPBM-culture supernatants. Cox-2 mRNA expression was measured by real-time RT-PCR of total RNA isolated from HPBM. Both, CT and CP, stimulated PGE(2) production of HPBM in vitro. Equivalent numbers of CT per host cell induced a higher PGE(2)-response compared to CP. The amount of synthesized PGE(2) depended on the chlamydial multiplicity of infection (MOI). Even at an MOI of 10 the amount of CT- and CP-induced prostaglandin, respectively, was lower than the amount of prostaglandin induced by E. coli lipopolysaccharide (LPS) at a concentration of 10microg/ml. In contrast to stimulation with LPS, Chlamydia-induced PGE(2) production as well as cox-2 mRNA decreased after day 1 post infection (p.i.). These data indicate that Chlamydia stimulate PGE(2) production in human monocytes. Since Chlamydia are often contaminated by mycoplasma, the influence of mycoplasma on the prostaglandin production was investigated additionally. Mycoplasma fermentans (MF) also stimulated PGE(2) production. The co-infection of mycoplasma and Chlamydia resulted in an additive effect in the production of PGE(2). Thus it is important to use host cells and Chlamydia free of mycoplasma contamination for the analysis of Chlamydia-induced prostaglandin production.

Ibuprofen Inhibits Survival of Bladder Cancer Cells by Induced Expression of the p75NTR Tumor Suppressor Protein

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to reduce inflammation and as analgesics by inhibition of cyclooxygenase-2. At higher concentrations, some NSAIDs inhibit proliferation and induce apoptosis of cancer cells. Although several molecular mechanisms have been postulated to explain the anticancer effects of NSAIDs, they do not involve merely the inhibition of cyclooxygenase-2, and a more proximate initiator molecule may be regulated by NSAIDs to inhibit growth. The p75 neurotrophin receptor (p75NTR) is a proximate cell membrane receptor glycoprotein that has been identified as a tumor and metastasis suppressor. We observed that NSAID treatment of cell lines from bladder and other organs induced expression of the p75NTR protein. Of the different types of NSAIDs examined, ibuprofen was more efficacious than aspirin and acetaminophen and comparable with (R)-flurbiprofen and indomethacin in induction of p75NTR protein expression. This rank order NSAID induction of the p75NTR protein correlated with the ability of these NSAIDs to reduce cancer cell survival. To examine a mechanistic relationship between ibuprofen induction of p75NTR protein and inhibition of survival, bladder cancer cells were transfected with ponasterone A-inducible vectors that expressed a death domain-deleted (DeltaDD) or intracellular domain-deleted (DeltaICD) p75NTR product that acts as a dominant negative antagonist of the intact p75NTR protein. Expression of DeltaDD and DeltaICD rescued cells from ibuprofen inhibition of growth. These observations suggest that p75NTR is an important upstream modulator of the anticancer effects of NSAIDs and that ibuprofen induction of the p75NTR protein establishes an alternate mechanism by which ibuprofen may exert an anticancer effect.

Cox-2 inhibition abrogates Chlamydia pneumoniae-induced PGE2 and MMP-1 expression

Peripheral blood monocytes (PBMC) promote vascular inflammation and atherosclerosis. Chlamydia pneumoniae (Cp) infection of PBMC is found in atherosclerotic patients, appears refractory to antibiotics, and may predispose to vascular damage. In Cp-infected human PBMC we analyzed the role of cyclooxygenase-2 (Cox-2) for the proatherosclerotic key mediators prostaglandin E2 (PGE2) and interstitial collagenase (MMP-1). Cp infection resulted in rapid and sustained Cox-2 mRNA and protein stimulation depending on p38 and p44/42 MAPkinases. Subsequent upregulation of PGE synthase and MMP-1 was completely abrogated by the selective Cox-2 inhibitor NS398. Enhanced synthesis of PGE2 and MMP-1 in Cp infected PBMC is mediated through initiation of the p38 and p44/42 MAPK pathways and requires sustained Cox-2 activation. Selective Cox-2 inhibitors, currently under investigation for cardiovascular risk reduction, may represent a novel therapeutic option for patients with endovascular Cp infection as they target the actuated pathological signal transduction cascade in persistently infected PBMC.

Chlamydia pneumoniae decreases smooth muscle cell proliferation through induction of prostaglandin E2 synthesis

Chlamydia pneumoniae may modulate the proliferation of smooth muscle cells (SMC) in atherosclerotic plaques. Conditioned medium from C. pneumoniae-infected SMC decreased the proliferation of uninfected SMC. Treatment of infected cells with the cyclooxygenase-2 inhibitor NS-398 [N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide] suppressed the up-regulation of prostaglandin E(2) (PGE(2)) and abolished the antimitogenic effect of conditioned medium, suggesting that C. pneumoniae can decrease SMC proliferation via stimulation of PGE(2) synthesis.

Acetylbritannilatone suppresses NO and PGE2 synthesis in RAW 264.7 macrophages through the inhibition of iNOS and COX-2 gene expression

In order to elucidate the mechanism of anti-inflammatory effect of 1-o-acetylbritannilatone (ABL) isolated from Inula Britannica-F, we investigated ABL for its ability to inhibit the inflammatory factor production in RAW 264.7 macrophages. The studies showed that ABL not only inhibited LPS/IFN-gamma-mediated nitric oxide (NO) production and inducible nitric synthase (iNOS) expression, but also decreased LPS/IFN-gamma-induced prostaglandin E2 (PGE2) production and cyclo-oxygenase-2 (COX-2) expression in a concentration-dependent manner. EMSA demonstrated that ABL inhibited effectively the association of NF-kappaB, which is necessary for the expression of iNOS and COX-2, with its binding motif in the promoter of target genes. These data suggest that ABL suppress NO and PGE2 synthesis in RAW 264.7 macrophages through the inhibition of iNOS and COX-2 gene expression, respectively. The anti-inflammatory effect of ABL involves blocking the binding of NF-kappaB to the promoter in the target genes and inhibiting the expression of iNOS and COX-2.