Mechanism of TNFalpha-induced IL-1alpha, IL-1beta and IL-6 expression in human cardiac fibroblasts: effects of statins and thiazolidinediones.
OBJECTIVE
In addition to direct effects on myocardial cell function, tumor necrosis factor alpha (TNFalpha) contributes to adverse cardiac remodeling by increasing production of other pro-inflammatory cytokines [e.g. interleukin (IL)-1 and IL-6]. Both statins and thiazolidinediones (TZDs) have beneficial effects on cardiac remodeling, possibly due to their anti-inflammatory properties. The present study examined the mechanisms by which TNFalpha stimulates expression of pro-inflammatory cytokines in cultured human cardiac fibroblasts and determined the effects of statin or TZD treatment.


METHODS
Human cardiac fibroblasts were cultured from biopsies of right atrial appendages. Cytokine mRNA expression and secretion was measured using quantitative real-time RT-PCR and ELISA. Activation of signaling pathways was determined by immunoblotting with phospho-specific antibodies.


RESULTS
TNFalpha (0.1-10 ng/ml) stimulated IL-6, IL-1alpha and IL-1beta mRNA expression in cardiac fibroblasts in a concentration-dependent manner. Pharmacological inhibitors and receptor-neutralizing antibodies established that both TNFalpha-induced IL-6 and IL-1beta expression was mediated via the TNFRI receptor and p38 mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/Akt and nuclear factor (NF)-kappaB pathways. In contrast, TNFalpha-induced IL-1alpha expression required both TNFRI and TNFRII subtypes and p38 MAPK and PI3K/Akt pathways, but was negatively regulated by the NF-kappaB pathway. Neither statins (simvastatin, fluvastatin) nor TZDs (ciglitazone, rosiglitazone, troglitazone) had inhibitory effects on TNFalpha-induced IL-6 secretion or IL-1alpha/beta mRNA expression; indeed, cytokine expression was increased in response to TZDs.


CONCLUSIONS
Our data provide important insights into the regulation of pro-inflammatory cytokine expression in human cardiac fibroblasts and suggest that the myocardial anti-inflammatory effects of statins and TZDs are not due to inhibition of TNFalpha-induced IL-1 or IL-6 expression by cardiac fibroblasts.
Turner
Neil A
NA
Academic Unit of Cardiovascular Medicine, Leeds Institute of Genetics, Health and Therapeutics (LIGHT), University of Leeds, Leeds LS2 9JT, UK. n.a.turner@leeds.ac.uk
Mughal
Romana S
RS
Warburton
Philip
P
O'Regan
David J
DJ
Ball
Stephen G
SG
Porter
Karen E
KE
D000704:Analysis of Variance; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002478:Cells, Cultured; D002839:Chromans / Q000494:pharmacology; D003327:Coronary Disease / Q000276:immunology; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D000077340:Fluvastatin; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D053582:Interleukin-1alpha / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D053583:Interleukin-1beta / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D015850:Interleukin-6 / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D007378:Interleukins / Q000096:biosynthesis*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000276:immunology*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000276:immunology; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D000077154:Rosiglitazone; D015398:Signal Transduction / Q000187:drug effects*; D019821:Simvastatin / Q000494:pharmacology; D013268:Stimulation, Chemical; D045162:Thiazolidinediones / Q000494:pharmacology*; D000077288:Troglitazone; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D002839:Chromans; D005229:Fatty Acids, Monounsaturated; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007211:Indoles; D053582:Interleukin-1alpha; D053583:Interleukin-1beta; D015850:Interleukin-6; D007378:Interleukins; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D045162:Thiazolidinediones; D014409:Tumor Necrosis Factor-alpha; D000077154:Rosiglitazone; D000077340:Fluvastatin; D019821:Simvastatin; D000077288:Troglitazone; C039671:ciglitazone