Streptococcus pneumoniae induced c-Jun-N-terminal kinase- and AP-1 -dependent IL-8 release by lung epithelial BEAS-2B cells

BACKGROUND: Although pneumococcal pneumonia is one of the most common causes of death due to infectious diseases, little is known about pneumococci-lung cell interaction. Herein we tested the hypothesis that pneumococci activated pulmonary epithelial cell cytokine release by c-Jun-NH(2)-terminal kinase (JNK) METHODS: Human bronchial epithelial cells (BEAS-2B) or epithelial HEK293 cells were infected with S. pneumoniae R6x and cytokine induction was measured by RT-PCR, ELISA and Bioplex assay. JNK-phosphorylation was detected by Western blot and nuclear signaling was assessed by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP). JNK was modulated by the small molecule inhibitor SP600125 and AP1 by transfection of a dominant negative mutant. RESULTS: S. pneumoniae induced the release of distinct CC and CXC, as well as Th1 and Th2 cytokines and growth factors by human lung epithelial cell line BEAS-2B. Furthermore, pneumococci infection resulted in JNK phosphorylation in BEAS-2B cells. Inhibition of JNK by small molecule inhibitor SP600125 reduced pneumococci-induced IL-8 mRNA expression and release of IL-8 and IL-6. One regulator of the il8 promoter is JNK-phosphorylated activator protein 1 (AP-1). We showed that S. pneumoniae time-dependently induced DNA binding of AP-1 and its phosphorylated subunit c-Jun with a maximum at 3 to 5 h after infection. Recruitment of Ser(63/73)-phosphorylated c-Jun and RNA polymerase II to the endogenous il8 promoter was found 2 h after S. pneumoniae infection by chromatin immunoprecipitation. AP-1 repressor A-Fos reduced IL-8 release by TLR2-overexpressing HEK293 cells induced by pneumococci but not by TNFα. Antisense-constructs targeting the AP-1 subunits Fra1 and Fra2 had no inhibitory effect on pneumococci-induced IL-8 release. CONCLUSION: S. pneumoniae-induced IL-8 expression by human epithelial BEAS-2B cells depended on activation of JNK and recruitment of phosphorylated c-Jun to the il8 promoter

Advances in adipose tissue metabolism.

International audienceThis review will focus on the recent findings in adipose tissue metabolism with special attention to human adipocyte biology and physiology. There are major advances stemming from the concomitant results obtained from studies on mature human adipocytes, human preadipocytes differentiated in vitro and murine adipose cell lines. Physiological developments have been based on the expanded utilization of various kinds of murine transgenic models and physiological techniques such as microdialysis, open-flow microperfusion, arteriovenous techniques and the utilization of deuterium- or tritium-labelled metabolites that have provided a number of physiological advances in the understanding of human adipose tissue physiology. Gene expression profiling studies and nutrigenomics are emerging methods that herald interesting approaches for the future. An overview of recent discoveries in the mechanisms involved in the control of free fatty acid uptake, triacylglycerol synthesis and fat deposition will be discussed, as well as recent advances in the mechanisms involved in the lipolytic pathways, the role of lipases and perilipins. In addition, the in vivo validation of catecholamine action and the discovery of the lipolytic effects of natriuretic peptides will also be covered