Genomic Variations Within DEFB1 Are Associated with the Susceptibility to and the Fatal Outcome of Severe Sepsis in Chinese Han Population
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Genes and Immunity (2007) 8, 439–443 & 2007 Nature Publishing Group All rights reserved 1466-4879/07 $30.00 www.nature.com/gene SHORT COMMUNICATION Genomic variations within DEFB1 are associated with the susceptibility to and the fatal outcome of severe sepsis in Chinese Han population Q-X Chen, C Lv, L-X Huang, B-L Cheng, G-H Xie, S-J Wu and X-M Fang Department of Anesthesiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China Sepsis is a systemic inflammatory response syndrome to infection. Human b-defensin 1 (DEFB1) is a multifunctional mediator in infection and inflammation, which has been largely explored in ex vivo studies. The present case–control study was designed to investigate whether DEFB1 genomic variations are associated with the susceptibility to and the outcome of severe sepsis in 211 patients with severe sepsis and 157 ethnic-matched healthy controls. After correcting for multiple testing, the À44G/C was the only polymorphism found to show significant associations with both the susceptibility to and the fatal outcome of severe sepsis (P ¼ 0.0049, odd ratio (OR) 1.971 and P ¼ 0.002, OR 2.406, respectively). Haplotype À20A/À44C/À52G showed a protective role against severe sepsis (P ¼ 0.0066, OR 0.6751), whereas haplotype À20G/À44G/À52G served as a risk factor for the fatal outcome of severe sepsis (P ¼ 0.0052, OR 2.427). These findings provide further evidence that b-defensin 1 may play a role in the pathogenesis of severe sepsis. Genes and Immunity (2007) 8, 439–443; doi:10.1038/sj.gene.6364401; published online 17 May 2007 Keywords: human b-defensin 1; DEFB1; SNP; haplotype; severe sepsis; association study Introduction adaptive immunity.16 Evidence suggests that DEFB1 may play an important role during the course of infection as Sepsis is an infection-initiated systemic inflammatory well as inflammation.15,17,18 reaction syndrome resulting from the interactions be- The cluster of human defensin genes including a- tween environmental and genetic factors.1,2 Studies defensin genes and at least four b-defensin genes is confirmed that single nucleotide polymorphisms (SNPs) located in chromosome 8p22–23.5 This region containing in some particular genes, such as tumor necrosis factor a number of genes related to the innate immunity and locus, interleukin-1 receptor antagonist, plasminogen the nervous system shows a strikingly high polymorphic activator inhibitor-1 and so on, play a critical role in rate in the human population.19 Recent studies found sepsis.3,4 that the genes coding a-defensins 1 (DEFA1) and 3 Defensins are cysteine-rich cationic antimicrobial (DEFA3) as well as b-defensins 2 (DEFB4), 3 (DEFB103) polypeptides with three disulfide bridges and are and 4 (DEFB104) exhibit copy number polymorphisms, expressed in plants, insects and mammals.5,6 Human b- while the DEFB1 gene was a single copy gene containing defensin 1 (DEFB1, hBD-1) was the first characterized several SNPs.20–23 The SNPs in DEFB1 have been human b-defensin identified in hemofiltrate.7 DEFB1 is associated with the pathogenesis of asthma and chronic constitutively expressed mainly in kidney, keratinocytes, obstructive pulmonary disease (COPD) as well as 8,9 oral cavity, as well as in urogenital tract. The in vitro infectious disease.24–28 However, the genetic predisposi- expression of DEFB1 can be upregulated by LPS, IL-1b, tion of individuals carrying these SNPs to sepsis remains interferon-g (IFN-g) and arginine.10–12 In vivo, elevated unknown. Hence, the present study was designed to levels of DEFB1 in body fluid were observed in investigate the association of genomic variants within individuals suffering from sepsis and infectious dis- DEFB1 and severe sepsis. eases.13,14 Moreover, the inducible expression of DEFB1 showed interindividual variability upon infection or LPS stimulation.10,15 In addition, DEFB1 has shown chemoat- Results tractant properties for dendritic cells and memory T cells via chemokine receptor CCR6, which links innate and All the enrolled patient and controls were Han Chinese. In patients with severe sepsis, 46.9% individuals have experienced surgical or traumatic history. Severe acute Correspondence: Dr X-M Fang, Department of Anesthesiology, The pancreatitis (18.5%) was the most frequent initial First Affiliated Hospital, College of Medicine, Zhejiang University, diagnosis, followed by gastrointestinal perforation or Qingchun Road 79, Hangzhou 310003, China. E-mail: [email protected] intestinal fistula after abdominal operation (17.5%), Received 31 January 2007; revised 9 April 2007; accepted 16 April pneumonia (17.1%), trauma (14.2%) and biliary duct or 2007; published online 17 May 2007 liver infection (10.4%). While lung (42.6%), abdomen SNPs in DEFB1 and severe sepsis Q-X Chen et al 440 (19.9%) and blood (17.5%) were the main source of age and gender as covariates confirmed the above infection. For treatment of severe sepsis, surgical inter- associations (Po0.05, OR 1.735, 95% CI 1.030–2.958 and ventions were applied for 44.5% patients. Meanwhile, Po0.05, OR 2.741, 95% CI 1.128–6.660, respectively). broad-spectrum antibiotics were widely used in all the Linkage disequilibrium (LD) analysis showed that patients. The most commonly administered antibiotics SNPs À52A/G, À44C/G and À20A/G were in strong were Tienam (Imipenem plus Cilastatin, 40.3% patients), LD. Three most common haplotypes were found in the Sulperazon (Sulbactam plus Cefoperazone, 39.8% pa- cohort (Table 2). The haplotype À20G/À44G/À52G was tients), Vancocin (Vancomycin Hydrochloride for intra more frequent in non-survivors than in survivors (17.1 vs venous, 33.2% patients) and Tazocin (Piperacillin, 28.9% 7.7%; P ¼ 0.0052, OR 2.427, 95% CI 1.307–4.507). How- patients). Antifungal agents were used in 37.4% patients. ever, the frequency of haplotype À20A/À44C/À52G in The allele frequency and genotype frequency of the control and severe sepsis group was 41.7 and 32.0%, two groups were shown in Table 1. Of note, the mutant respectively (P ¼ 0.0066, OR 0.6751, 95% CI 0.4850– allele (A allele) of SNP 1654G/A, which had been 0.8902). reported in another study,27 was not detected in the present cohorts. The genotype-allele distribution for the assayed loci followed Hardy–Weinberg equilibrium in Discussion both patients and controls (P40.05). After correcting for In this study, the À44G/C variation was associated with multiple testing, the frequency of À44G allele in patients both the susceptibility to and the fatal outcome of severe with severe sepsis was significantly higher than that in sepsis. Furthermore, the À20G/À44G/À52G haplotype controls (15.64 vs 8.60%; P ¼ 0.0049, OR 1.971, 95% CI was associated with the fatal outcome of severe sepsis, 1.227–3.166). Furthermore, in severe septic patients, the whereas the À20A/À44C/À52G haplotype showed a frequency of À44G-allele was 20.91% in non-survivors, protective role against severe sepsis. To our knowledge, while it was 9.90% in survivors (P ¼ 0.002, OR 2.406, 95% this is the first association study to investigate the genetic CI 1.368–4.232). The logistic regression model including impact of DEFB1 polymorphisms on sepsis. Table 1 Allelic and genotype frequencies of variations À1816A/G, À390A/T, À52A/G, À44C/G, À20A/G and 1654G/A in patients with severe sepsis and controls SNPs Severe sepsis (n ¼ 211) Control (n ¼ 157) P-valuea Survivor (n ¼ 101) Non-survivor (n ¼ 110) P-valuea N (%) N (%) N (%) N (%) À1816A/G AA 157 (74.41) 114 (72.61) — 82 (81.19) 75 (68.18) — AG 44 (20.85) 36 (22.93) — 16 (15.84) 28 (25.46) — GG 10 (4.74) 7 (4.46) 0.89 3 (2.97) 7 (6.36) 0.087 A 358 (84.83) 264 (84.08) — 180 (89.11) 178 (80.91) — G 64 (15.17) 50 (15.92) 0.78 22 (10.89) 42 (19.09) 0.021 À390A/T AA 63 (29.86) 43 (27.39) — 36 (35.65) 27 (24.55) — AT 95 (45.02) 75 (47.77) — 43 (42.57) 52 (47.27) — TT 53 (25.12) 39 (24.84) 0.84 22 (21.78) 31 (28.18) 0.193 A 221 (52.37) 161 (51.27) — 115 (56.93) 106 (48.18) — T 201 (47.63) 153 (48.73) 0.77 87 (43.07) 114 (51.82) 0.079 À52A/G AA 62 (29.38) 39 (24.48) — 34 (33.66) 28 (25.45) — AG 98 (46.44) 75 (47.77) — 48 (47.53) 50 (45.46) — GG 51 (24.18) 43 (27.39) 0.58 19 (18.81) 32 (29.09) 0.169 A 222 (52.61) 153 (48.73) — 116 (57.42) 106 (48.18) — G 200 (47.39) 161 (51.27) 0.30 86 (42.58) 114 (51.82) 0.064 À44C/G CC 153 (72.51) 130 (82.80) — 83 (82.18) 70 (63.64) — CG 50 (23.70) 27 (17.20) — 16 (15.84) 34 (30.91) — GG 8 (3.79) 0 (0) 0.011 2 (1.98) 6 (5.45) 0.009 C 356 (84.36) 287 (91.40) — 182 (90.10) 174 (79.09) — G 66 (15.64) 27 (8.60) 0.0049 20 (9.90) 46 (20.91) 0.002 À20A/G AA 29 (13.74) 33 (21.02) — 14 (13.86) 15 (13.64) — AG 91 (43.13) 73 (46.50) — 45 (44.56) 46 (41.82) — GG 91 (43.13) 51 (32.48) 0.058 42 (41.58) 49 (44.54) 0.905 A 149 (35.31) 139 (44.27) — 73 (36.14) 76 (34.54) — G 273 (64.69) 175 (55.73) 0.014 129 (63.86) 144 (65.46) 0.760 Abbreviation: SNP, single nucleotide polymorphism.