Haplotype-dependent differential activation of the human IL-10 gene promoter in macrophages and trophoblasts: implications for placental IL-10 deficiency and pregnancy complications.
OBJECTIVE
polymorphic changes in the IL-10 gene promoter have been identified that lead to altered IL-10 production. We hypothesized that because of these genotypic changes, the IL-10 promoter might be expressed in a cell type-specific manner and may respond differentially to inflammatory triggers.


METHODS
we created reporter gene promoter constructs containing GCC, ACC, and ATA haplotypes using DNA from patients harboring polymorphic changes at -1082 (G→A), -819 (C→T), and -592 (C→A) sites in the IL-10 promoter. These individual luciferase reporter constructs were transiently transfected into either primary term trophoblasts or THP1 monocytic cells. DNA-binding studies were performed to implicate the role of the Sp1 transcription factor in response to differential promoter activity.


RESULTS
our results suggest that the GCC promoter construct was activated in trophoblast cells in response to lipopolysaccharide (LPS), as demonstrated by reporter gene expression, but not in monocytic cells. The ACC construct showed weaker activation in both cell types. Importantly, while the ATA promoter was constitutively activated in both cell types, its expression was selectively repressed in response to LPS, but only in trophoblasts. DNA-nuclear protein binding assays with nuclear extracts from LPS treated or untreated cells suggested a functional relevance for Sp1 binding differences at the -592 position.


CONCLUSIONS
these results demonstrate cell type-specific effects of the genotypic changes in the IL-10 gene promoter. These responses may be further modulated by bacterial infections or other inflammatory conditions to suppress IL-10 production in human trophoblasts.
Sharma
Surendra
S
Department of Pediatrics, Women and Infants Hospital-Warren Alpert Medical School of Brown University, Providence, Rhode Island 02905, USA. ssharma@wihri.org
Stabila
Joan
J
Pietras
Linda
L
Singh
Arvind R
AR
McGonnigal
Bethany
B
Ernerudh
Jan
J
Matthiesen
Leif
L
Padbury
James F
JF
D002460:Cell Line; D003001:Cloning, Molecular; D005260:Female; D006239:Haplotypes; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D009928:Organ Specificity; D010922:Placenta Diseases / Q000235:genetics* / Q000276:immunology; D011110:Polymorphism, Genetic; D011247:Pregnancy; D011248:Pregnancy Complications / Q000235:genetics* / Q000276:immunology; D011401:Promoter Regions, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000276:immunology; D014327:Trophoblasts / Q000276:immunology / Q000378:metabolism* / Q000473:pathology
D016753:Interleukin-10