Enhancer polymorphism rs10865710 associated with traumatic sepsis is a regulator of PPARG gene expression

Background

Peroxisome proliferator-activated receptor gamma (PPARγ) is a major regulator in sepsis. Our previous study identified the enhancer polymorphism rs10865710C/G to be associated with susceptibility to sepsis in trauma patients. We performed two-stage cohort studies integrating biological experiments of potential functional variants that modify susceptibility to traumatic sepsis.

Methods

Improved multiplex ligation detection reaction (iMLDR) was used to genotype rs10865710 in 797 Han Chinese trauma patients in Chongqing. Clinical relevance was validated in 334 patients in Guizhou. The potential function of rs10865710 in transcriptional regulation was explored through a dual luciferase reporter assay and electrophoretic mobility shift assay (EMSA). Expression of PPARγ was assessed by expression quantitative trait locus (e-QTL) and western blot analyses.

Results

The association results confirmed rs10865710 to be significantly strongly associated with sepsis risk in trauma patients of the Chongqing and Guizhou cohorts (OR = 1.41 (1.11–1.79), P = 0.004 and OR = 1.45 (1.01–2.09), P = 0.046, both for allele-dose effect, respectively). A meta-analysis of both cohorts and a previous study indicated strong evidence for this association (OR = 1.41 (1.17–1.71), P = 0.0004 for the dominant model, OR = 1.78 (1.34–2.36), P < 0.0001 for the recessive model and OR = 1.38 (1.20–1.58), P < 0.0001 for the allelic model). Functional experiments verified that rs10865710 was a causative variant influencing enhancer activity (G vs. C, 0.068 ± 0.004 vs. 0.096 ± 0.002, P = 0.0005) and CREB2 binding. Expression analysis also indicatevd rs10865710 genotypes to be associated with levels of PPARγ expression (P = 9.2 × 10⁻⁵ for dominant effect and P = 0.005 for recessive effect).

Conclusions

Our study provides evidence that the enhancer-region polymorphism rs10865710 might influence transcription factor binding and regulate PPARγ expression, thus conferring susceptibility to traumatic sepsis.

Trial registration

ClinicalTrials.gov, NCT01713205. Registered 18 October 2012, retrospectively registered.