The Interleukin-6 G(−174)C Promoter Polymorphism Does Not Determine Plasma Interleukin-6 Concentrations in Experimental Endotoxemia in Humans

A meta-analysis of the association between inflammatory cytokine polymorphism and neonatal sepsis

OBJECTIVE

The purpose of this study is to investigate the relationship between single nucleotide polymorphisms of inflammatory cytokines and neonatal sepsis through meta-analysis.

METHODS

We collected research literature on the correlation between inflammatory cytokine polymorphisms and neonatal sepsis published before August 2023 through computer searches of databases such as PubMed, Embase, etc. The Stata 14.0 software was utilized for Meta-analysis. To assess heterogeneity, the chi-squared Q-test and I2 statistics were used. The Egger and Begg tests were conducted to determine the possibility of publication bias.

RESULTS

After reviewing 1129 articles, 29 relevant articles involving 3348 cases and 5183 controls were included in the study. The meta-analysis conducted on IL-1βrs1143643 polymorphism revealed significant findings: the T allele genotype has a lower risk of neonatal sepsis(P = 0.000, OR = 0.224, 95% CI: 0.168-0.299), while the TC and TT genotypes showed an increased risk(TC: P = 0.000,OR = 4.251, 95% CI: 2.226-8.119; TT: P = 0.019,OR = 2.020, 95% CI: 1.122-3.639). Similarly, newborns with the IL-6-174 CC genotype had a significantly higher risk of sepsis(P = 0.000,OR = 1.591, 95% CI: 1.154-2.194), while those with the IL-8-rs4073 TT (P = 0.003,OR = 0.467, 95% CI: 0.280-0.777)and TT + AA(P = 0.003,OR = 0.497, 95% CI: 0.315-0.785) genotypes had a significantly lower risk of sepsis. For the IL-10-1082 gene, newborns with the AA genotype(P = 0.002,OR = 1.702, 95% CI: 1.218-2.377), as well as those with the AA + GA genotype(P = 0.016,OR = 1.731, 95% CI: 1.108-2.705), had a significantly higher risk of sepsis. Lastly, newborns carrying the TNF-α-308 A allele (P = 0.016,OR = 1.257, 95% CI: 1.044-1.513)or the AA genotype(P = 0.009,OR = 1.913, 95% CI: 1.179-3.10) have a significantly increased risk of sepsis. Notwithstanding, additional studies must be included for validation. Applying these cytokines in clinical practice and integrating them into auxiliary examinations facilitates the early detection of susceptible populations for neonatal sepsis, thereby providing a new diagnostic and therapeutic approach for neonatal sepsis.

Low-Dose Whole-Lung Irradiation for COVID-19 Pneumonia: Final Results of a Pilot Study

Introduction

Radiation therapy (RT), commonly used in cancer management, has been considered as one of the potential treatments for COVID-19 pneumonia. Here, we present the results of the pilot trial evaluating low-dose whole-lung irradiation (LD-WLI) in patients with COVID-19 pneumonia.

Methods

Ten patients with moderate COVID-19 pneumonia were treated with LD-WLI in a single fraction of 0.5 or 1.0 Gy along with the national protocol. The primary endpoint was an improvement in Spo₂. The secondary endpoints were the number of days of hospital/intensive care unit stay, the number of intubations after RT, 28-day mortality, and changes in biomarkers. The response rate (RR) was defined as an increase in Spo₂ upon RT with a rising or constant trend in the next 2 days, clinical recovery (CR) including patients who were discharged or acquired Spo₂ ≥93% on room air, and 28-day mortality rate defined based on days of RT.

Results

The median age was 75 years (80% male). Five, 1, and 4 patients received single-dose 0.5 Gy, two-dose 0.5 Gy, and single-dose 1.0 Gy LD-WLI, respectively. The mean improvement in Spo₂ at days 1 and 2 after RT was 2.4% (±4.8%) and 3.6% (±6.1%), respectively, with improvement in 9 patients after 1 day. Five, 1, and 4 patients were discharged, opted out of the trial, and died in the hospital, respectively. Two of 5 discharged patients died within 3 days at home. Among discharged patients, the Spo₂ at discharge was 81% to 88% in 3 patients and 93% in the other 2 patients. Overall, the RR and CR were 63.6% and 55.5%, respectively. The RR, CR, and 28-day mortality of the single 0.5 Gy and 1.0 Gy WLI groups were 71.4% versus 50% (P = .57), 60% versus 50% (P = .64), and 50% versus 75% (P = .57), respectively.

Conclusion

LD-WLI with a single fraction of 0.5 Gy or 1 Gy is feasible. A randomized trial with patients who do not receive radiation is required to assess the efficacy of LD-WLI for COVID-19.

Effect of maternal and neonatal interleukin-6 - 174 G/C polymorphism on preterm birth and neonatal morbidity

OBJECTIVE

The aim of this study was to analyze maternal and neonatal interleukin 6 (IL-6) (-174 G/C) polymorphism and to determine effect on preterm birth and neonatal morbidity.

STUDY DESIGN

One hundred and sixty-four mothers (100 term births, 64 preterm births) and 183 newborn infants who were 100 healthy term and 83 preterm babies followed in newborn intensive care units were evaluated. PCR-RFLP was performed for IL-6 (-174 G/C) genotyping.

RESULTS

The rate of GG genotype in mothers of term and preterm infants were 54% (n = 54/100), 75% (n = 48/64), respectively (p > .05) and the rate of GC + CC genotype was 46% (n = 46/100) and 25% (n = 16/64) in mothers giving term and preterm birth (PTB), respectively (p < .05). Additionally, the rate of GG genotype was 65% (n = 65/100) and 81.9% (n = 68/83) in term infants and preterm infants, respectively. GC + CC genotype was 35% (n = 35/100) in term infants and 18.1% (n = 15/83) in preterm infants (p < .05). The effect of IL-6 (-174) GC + CC genotype on PTB was statistically significant.

CONCLUSION

The IL-6 174 G/C gene polymorphism was significantly different between mothers who were giving to term and preterm birth. The presence of polymorphism is protective against preterm birth and was not associated with neonatal outcome.

A Randomized Controlled Trial of the Effects of Febuxostat Therapy on Adipokines and Markers of Kidney Fibrosis in Asymptomatic Hyperuricemic Patients With Diabetic Nephropathy

BACKGROUND

In observational studies, higher uric acid levels are associated with metabolic syndrome, diabetes, and kidney disease.

OBJECTIVE

The objective of this study is to examine whether reduction of plasma uric acid with febuxostat, a xanthine oxido reductase inhibitor, impacts adipose tissue oxidative stress, adipokines, and markers of systemic inflammation or kidney fibrosis.

DESIGN

This was a double-blinded randomized controlled trial.

SETTING

Academic university setting was used.

PATIENTS

Overweight or obese adults with hyperuricemia and type 2 diabetic nephropathy were included.

MEASUREMENTS

Adipose tissue thiobarbituric acid reducing substances (TBARS) and adiponectin concentrations and urinary transforming growth factor-β (TGF-β) were primary endpoints. Plasma C-reactive protein, high molecular weight-adiponectin, interleukin-6, tumor necrosis factor-α, and TBARS and albuminuria were among predefined secondary endpoints.

METHODS

Participants were randomly assigned to febuxostat (n = 40) or matching placebo (n = 40) and followed for 24 weeks.

RESULTS

Baseline plasma uric acid levels were 426 ± 83 µmol/L; 95% completed the study. Estimated glomerular filtration rate (eGFR) declined from 54 ± 17 mL/min/1.73 m² at baseline to 51 ± 17 mL/min/1.73 m² at 24 weeks (P = .05). In separate mixed-effects models, compared with placebo, febuxostat reduced uric acid by 50% (P < .001) but had no significant effects on subcutaneous adipose tissue TBARS (-7.4%, 95% confidence interval [CI], 57.4%-101.4%) or adiponectin (6.7%, 95% CI, 26.0%-53.8%) levels or urinary TGF-β/creatinine ratio (18.0%, 95% CI, 10.0%-54.8%) or secondary endpoints.

LIMITATIONS

Relatively modest sample size and short duration of follow-up.

CONCLUSIONS

In this population with progressive diabetic nephropathy, febuxostat effectively reduced plasma uric acid. However, no detectable effects were observed for the prespecified primary or secondary endpoints.

TRIAL REGISTRATION

The study was registered in clinicaltrials.gov (NCT01350388).

Review: From therapy to experimental model: a hundred years of endotoxin administration to human subjects

This article is a review of studies in which endotoxin has been administered to human subjects for experimental purposes. Data are presented in tabular form so the reader can better appreciate the objectives of individual studies. Although the original intention was to focus on the adverse events associated with these studies, unexpected serious adverse events rarely have been reported.

Interleukin-6 gene polymorphisms in Egyptian children with febrile seizures: a case-control study

BACKGROUND

Febrile seizures are the most common form of childhood seizures. Among pro-inflammatory cytokines, interleukin-6 is the key acute-phase cytokine. To date, only a few studies concerned the association of interleukin-6 gene polymorphisms with febrile seizures.In this study, we aimed to investigate 3 cytokine single-nucleotide polymorphisms situated at positions -174 (G/C), -572 (G/C), and -597 (G/A) in the promoter region of the interleukin-6 gene for the first time in Egyptian children with febrile seizures.

METHODS

This was a case-control study included 100 patients with febrile seizure, and matched with age, gender, ethnicity 100 healthy control subjects. Interleukin-6 -174 (G/C), -572 (G/C), and -597 (G/A) polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while the serum IL6 levels were measured by ELISA method.

RESULTS

Compared to the controls subjects, the frequency of the -174 GG and -597 GG IL6 genotypes were observed to be increased in children with febrile seizures (OR: 4.17; 95 % CI: 1.86-9.49; P <0.01 and OR: 1.96; 95 % CI: 1.06-3.63;P <0.05, respectively). We found a significant positive association between the -597 GG genotype and susceptibility to complex febrile seizures as did the G allele at the same position (OR: 4.2; 95 % CI: 1.4-13.3 for the GG genotype; P <0.01) and (OR: 2.89; 95 % CI: 1.1-7.7 for the G allele; P <0.05 respectively). Our data revealed no association between IL6- genotypes and serum IL6 levels in patients with febrile seizures (P > 0.05).

CONCLUSION

In conclusion, our data brought a novel observation that the presence of a G allele or GG genotype at the -174 and the GG genotype at the -597 positions of the promoter region of the interleukin-6 gene constitute risk factors for developing febrile seizures in Egyptian children. Moreover, we observed a significant positive association between the IL6 -597 GG genotype and susceptibility to complex febrile seizures as did the G allele at the same position. However, we found no association between IL6- genotypes and serum IL6 levels in patients with febrile seizures.

Human experimental endotoxemia in modeling the pathophysiology, genomics, and therapeutics of innate immunity in complex cardiometabolic diseases

Inflammation is a fundamental feature of several complex cardiometabolic diseases. Indeed, obesity, insulin resistance, metabolic dyslipidemia, and atherosclerosis are all closely linked inflammatory states. Increasing evidence suggests that the infectious, biome-related, or endogenous activation of the innate immune system may contribute to the development of metabolic syndrome and cardiovascular disease. Here, we describe the human experimental endotoxemia model for the specific study of innate immunity in understanding further the pathogenesis of cardiometabolic disease. In a controlled, experimental setting, administration of an intravenous bolus of purified Escherichia coli endotoxin activates innate immunity in healthy human volunteers. During endotoxemia, changes emerge in glucose metabolism, lipoprotein composition, and lipoprotein functions that closely resemble those observed chronically in inflammatory cardiovascular disease risk states. In this review, we describe the transient systemic inflammation and specific metabolic consequences that develop during human endotoxemia. Such a model provides a controlled induction of systemic inflammation, eliminates confounding, undermines reverse causation, and possesses unique potential as a starting point for genomic screening and testing of novel therapeutics for treatment of the inflammatory underpinning of cardiometabolic disease.

IL6-174 G/C gene polymorphism and its relation to serum IL6 in Egyptian children with community-acquired pneumonia

Cytokines are involved in the pathogenesis of community acquired pneumonia (CAP). The aim of this study is to investigate the association of IL6-174 G/C gene polymorphism with CAP in Egyptian children, to assess its effect on CAP outcome and to determine its effect on the serum IL6 levels in these children. IL6-174 G/C gene polymorphism was genotyped in 210 Egyptian children (100 patients with CAP and 110 healthy controls) using PCR-RFLP, while the serum IL6 levels were measured by ELISA method. We found a significant association between the GG genotype, G allele of IL6-174 G/C SNP and susceptibility to CAP (P=0.02, 0.01 respectively). However, GG genotype and G allele were protective against severe sepsis (p=0.004), acute respiratory failure (p<0.001) and hospital mortality (p<0.001). Serum IL6 levels were significantly increased in these children while there was no relation between GG genotype and serum IL6. In conclusion, IL6-174 G/C gene polymorphism may contribute to susceptibility to CAP in Egyptian children.

α-Cyperone, isolated from the rhizomes of Cyperus rotundus, inhibits LPS-induced COX-2 expression and PGE2 production through the negative regulation of NFκB signalling in RAW 264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

The rhizomes of Cyperus rotundus (Cyperaceae) have been used in Asian traditional medicine for the treatment of several inflammatory diseases. However, the anti-inflammatory effects of α-cyperone, a major active compound of Cyperus rotundus, are poorly understood.

MATERIALS AND METHODS

PGE2 and cytokines released from cells were measured using an EIA assay kit. The expression of iNOS, COX-2, TNF-α, and IL-6 was measured by real-time RT-PCR and/or Western blot analysis. A luciferase assay was performed to measure the effect of α-cyperone on NFκB activity.

RESULTS

The n-hexane fraction of the 80% EtOH extract from the rhizomes of Cyperus rotundus was found to inhibit both NO and PGE2 production in RAW 264.7 cells. α-Cyperone isolated from the n-hexane fraction significantly inhibited PGE2 production by suppressing the LPS-induced expression of inducible COX-2 at both the mRNA and the protein levels. In contrast, α-cyperone had little effect on NO production and iNOS expression. Additionally, α-cyperone downregulated the production and mRNA expression of the inflammatory cytokine IL-6. Moreover, treatment with α-cyperone suppressed the transcriptional activity of NFκB and the nuclear translocation of the p65 NFκB subunit in LPS-induced RAW 264.7 cells.

CONCLUSION

The anti-inflammatory activity of α-cyperone is associated with the down-regulation of COX-2 and IL-6 via the negative regulation of the NFκB pathway in LPS-stimulated RAW 264.7 cells.

Influence of the IL6 gene in susceptibility to systemic sclerosis

OBJECTIVE

Systemic sclerosis (SSc) is a genetically complex autoimmune disease; the genetic component has not been fully defined. Interleukin 6 (IL-6) plays a crucial role in immunity and fibrosis, both key aspects of SSc. We investigated the influence of IL6 gene in the susceptibility and phenotype expression of SSc.

METHODS

We performed a large metaanalysis including a total of 2749 cases and 3189 controls from 6 white populations (Germany, The Netherlands, Norway, Spain, Sweden, and United Kingdom). Three IL6 single-nucleotide polymorphisms (SNP; rs2069827, rs1800795, and rs2069840) were selected by SNP tagging and genotyped using TaqMan(®) allele discrimination technology.

RESULTS

Individual SNP metaanalysis showed no evidence of association of the 3 IL6 genetic variants with the global disease. Phenotype analyses revealed a significant association between the minor allele of rs2069840 and the limited cutaneous SSc clinical form (Bonferroni p = 0.036, OR 1.14, 95% CI 1.04-1.25). A trend of association between the minor allele of the rs1800795 and the diffuse cutaneous SSc clinical form was also evident (Bonferroni p = 0.072, OR 0.86, 95% CI 0.77-0.96). In the IL6 allelic combination analyses, the GGC allelic combination rs2069827-rs1800795-rs2069840 showed an association with overall SSc (Bonferroni p = 0.016, OR 1.13, 95% CI 1.04-1.23).

CONCLUSION

Our results suggest that the IL6 gene may influence the development of SSc and its progression.

Melphalan exposure induces an interleukin-6 deficit in bone marrow stromal cells and osteoblasts

Bone marrow stromal cells (BMSC) and osteoblasts are critical components of the microenvironment that support hematopoietic recovery following bone marrow transplantation. Aggressive chemotherapy not only affects tumor cells, but also influences additional structural and functional components of the microenvironment. Successful reconstitution of hematopoiesis following stem cell or bone marrow transplantation after aggressive chemotherapy is dependent upon components of the microenvironment maintaining their supportive function. This includes secretion of soluble factors and expression of cellular adhesion molecules that impact on development of hematopoietic cells. In the current study, we investigated the effects of chemotherapy treatment on BMSC and human osteoblast (HOB) expression of interleukin-6 (IL-6) as one regulatory factor. IL-6 is a pleiotropic cytokine which has diverse effects on hematopoietic cell development. In the current study we demonstrate that exposure of BMSC or HOB to melphalan leads to decreases in IL-6 protein expression. Decreased IL-6 protein is the most pronounced following melphalan exposure compared to several other chemotherapeutic agents tested. We also observed that melphalan decreased IL-6 mRNA in both BMSC and HOB. Finally, using a model of BMSC or HOB co-cultured with myeloma cells exposed to melphalan, we observed that IL-6 protein was also decreased, consistent with treatment of adherent cells alone. Collectively, these observations are of dual significance. First, suggesting that chemotherapy induced IL-6 deficits in the bone marrow occur which may result in defective hematopoietic support of early progenitor cells. In contrast, the decrease in IL-6 protein may be a beneficial mechanism by which melphalan acts as a valuable therapeutic agent for treatment of multiple myeloma, where IL-6 present in the bone marrow acts as a proliferative factor and contributes to disease progression. Taken together, these data emphasize the responsiveness of the microenvironment to diverse stress that is important to consider in therapeutic settings.

Tumor necrosis factor-α -308 G>A and interleukin-6 -174 G>C promoter polymorphisms and pemphigus

The objective of this study was to analyze the possible involvement of the tumor necrosis factor (TNF)-α -308 G>A and interleukin-6 (IL-6) -174 G>C polymorphisms in the susceptibility and/or disease profile of pemphigus in Egyptian patients. Detection of TNF-α -308 G>A by amplification refractory mutation system and IL-6 -174 G>C by restriction fragment length polymorphism was performed for 70 patients and 203 controls. No significant differences were observed in the distribution of TNF-α -308 in pemphigus patients and controls. However, GA+AA genotypes were more frequent in pemphigus vulgaris (PV) patients only versus controls (p(c) = 0.046). The frequency of the C allele and CC/GC genotypes of IL-6 -174 was significantly higher in pemphigus patients and those with the 2 major clinical forms (PV and pemphigus foliaceus [PF]) compared with controls (p < 0.05). Comparison of the distribution of TNF-α -308 and IL-6 -174 variants in relation to clinical type of pemphigus (PV versus PF), activity score, recurrence, and demographic data of patients revealed no significant associations. The IL-6 -174 CC genotype represents a marker of increased susceptibility to pemphigus in Egyptian patients and GG genotype can be considered a low-risk genotype; TNF-α -308 A-containing genotypes contribute to the susceptibility to PV only.

The presence of functionally relevant toll-like receptor polymorphisms does not significantly correlate with development or outcome of sepsis

AIMS

Members of the toll-like receptor (TLR) family have been shown to play important roles in inflammatory responses. Single-nucleotide polymorphisms (SNPs) altering receptor activity may either have detectable effects or might be without results due to compensatory mechanisms. We determined the genotype frequencies of functionally relevant SNPs in TLR2, 4 and 5 in critically ill patients (n=150) from a multidisciplinary surgical intensive care unit (ICU). The inflammatory response (procalcitonin, C-reactive protein, white blood count) and clinical classification (Acute Physiology and Chronic Health Evaluation Score II, Simplified Acute Physiology Score II, Sepsis-related Organ Failure Assessment) were monitored daily.

RESULTS

The genetic polymorphisms correlate with neither development nor outcome of sepsis. No correlations were found between C-reactive protein or WBC and the investigated SNPs. In patients in the ICU with abdominal surgery and multiple trauma, the TLR2-R753Q SNP was associated with infection at ICU admission (p<0.01); and for carriers of the TLR4-D299G SNP, a trend was observed (p=0.0776). Patients with multiple trauma carrying the TLR4-D299G SNP displayed significantly higher levels of procalcitonin (p=0.0212).

CONCLUSIONS

None of the investigated SNPs clearly predicted outcome of sepsis-related multiorgan failure. TLR2-R753Q SNP may be a useful marker to identify patients with high risk to develop infections at ICU admission but should be validated in larger studies. Future SNP-arrays investigating predisposition for infection should include this SNP alone or in combination with other functionally relevant SNPs.

The inflammatory response is influenced by FXIII VAL 34 LEU polymorphism in a human LPS model

BACKGROUND

In sepsis, activation of coagulation and inhibition of fibrinolysis lead to microvascular thrombosis. The Val34Leu polymorphism affects the function of FXIII by increasing the rate of FXIII activation by thrombin, which results in an increased and faster rate of fibrin stabilization. Sepsis and multi-organ failure cause disturbance of the normal balance of inflammation and coagulation, one of the most frequent causes of death in ICU patients. Research in polymorphism has shown the possible influence of FXIII in coagulation and inflammation.

METHODS

We analyzed the influence of the common FXIII Val34Leu polymorphism on inflammatory and coagulation parameters in human experimental endotoxinemia. Healthy volunteers (n = 62) received 2 ng endotoxin (LPS) per kg body weight as a bolus infusion over 2 min. We developed a new mutagenic separated PCR assay for determination of the FXIII promoter polymorphism.

RESULTS

FXIII levels were higher for homozygous carriers of the FXIII polymorphism in comparison with wild-type 34 Val/Val and heterozygous 34 Val/Leu. Interestingly, persons homozygous for the FXIII Val34Leu polymorphism had lower monocyte and neutrophil counts throughout the observation period, yet prothrombin fragment 1+2 and D-dimer levels did not differ after LPS challenge.

CONCLUSION

Our findings indicate that the common FXIII Val34Leu polymorphism is associated with differences in monocyte and neutrophil cell counts in response to systemic LPS infusion in humans.

IL‐6 promoter polymorphism in patients with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which cytokines play an important role. The aim of the present study was to examine the interleukin-6 (IL-6) -174 promoter polymorphism in patients with RA and its association with disease susceptibility and activity.

METHODS

The study included 98 patients with RA diagnosed according to the criteria of the American College of Rheumatology. Polymerase chain reaction (PCR) amplification was used for analysis of the polymorphism at position -174 in the promoter of the IL-6 gene.

RESULTS

The distribution of IL-6 genotypes in RA patients did not differ from that in control subjects. Nevertheless, in patients with a GG genotype the active form of RA was more frequently diagnosed compared with homozygous CC and GC patients. Moreover, in carriers of two G alleles the parameters of disease activity score (DAS28), erythrocyte sedimentation rate (ESR), number of swollen and tender joints] were significantly increased.

CONCLUSION

We suggest that the IL-6 promoter polymorphism may be a genetic risk factor for RA activity.

The role of genomics in the neonatal ICU

Results of both the Human Genome and International HapMap Projects have provided the technology and resources necessary to enable fundamental advances through the study of DNA sequence variation in almost all fields of medicine, including neonatology. Genome-wide association studies are now practical, and the first of these studies are appearing in the literature. This article provides the reader with an overview of the issues in technology and study design relating to genome-wide association studies and summarizes the current state of association studies in neonatal ICU populations with a brief review of the relevant literature. Future recommendations for genomic association studies in neonatal ICU populations are also provided.

Higher IL-6 levels but not IL6 -174G>C or -572G>C genotype are associated with post-operative complication following coronary artery bypass graft (CABG) surgery

Large increases in inflammatory markers, particularly IL-6, occur after cardiac surgery. However, despite interventions to reduce the inflammatory response, great variability still remains which could in part be attributable to genetic predisposition. Since increased IL-6 levels following surgery are also associated with poorer outcome we sought to determine whether baseline and post-operative levels of Interleukin-6 (IL-6) and functional common variants of the Interleukin-6 (IL6) gene are associated with post-operative outcome following coronary artery bypass grafting (CABG). Caucasian patients undergoing first-time elective CABG were studied. IL-6 levels were measured pre-, 6h and 24h following surgery and genotypes for IL6 gene variants -174G>C and -572G>C were obtained. Clinical data was collected daily until patient discharge. Patient outcome was categorised as with (ICUC, n=177) and without (NICUC, n=189) a post-operative complication during the ICU period and with (POC, n=215) and without (NC, n=151) a post-operative complication during hospitalisation. IL-6 levels pre- and at 24h were greater in POC and ICUC than NC and NICUC, respectively. Pre- IL-6 levels independently predicted (for 1 standard deviation increase in log IL-6) POC (OR 1.4, 95% CI 1.1-1.7, p=0.008) and ICUC (OR 1.3, 95% CI 1.0-1.6, p=0.02) outcomes. Overall, the IL6-572G>C had an effect over time on IL-6 levels (p=0.04) and on IL-6 levels in NC (P=0.008) and NICUC (p=0.006). However, no associations were found with the IL6 -572G>C or -174G>C variants on IL-6 levels at individual time-points or by outcome group. Thus, in conclusion, elevated pre-operative IL-6 levels, but not IL6 gene variants predict poor patient outcome following CABG.

IL6 gene-wide haplotype is associated with susceptibility to acute lung injury

Experimental and clinical studies support the key role of interleukin 6 (IL-6), a potent proinflammatory cytokine, in the development of acute lung injury (ALI). Plasma IL-6 levels are influenced mainly by genetic determinants, and a -174G/C polymorphism of the gene has been recently associated with susceptibility to ALI. Here we aimed to validate the association of the IL6 gene with ALI in a case-control sample from Spain. DNA was isolated from 67 consecutive patients who fulfilled international criteria for severe sepsis and for ALI and 96 population-based controls drawn from the general population. Genotypes of the -174G/C polymorphism along with other 14 tagging variants of the IL6 gene were evaluated. Twenty polymorphisms unlinked to IL6 gene were additionally compared between cases and controls to rule out population stratification. None of the individual single-nucleotide polymorphisms was significantly associated with susceptibility to ALI. However, we found that a common haplotype from -1363 to +4835 from the transcription start site, and spanning the gene, conferred risk for susceptibility to ALI (odds ratio, 2.73; 95% confidence interval, 1.39-5.37; P = 0.003). Adjustment for relevant covariates did not modify this result. These data support the association of the IL6 gene with ALI susceptibility and illustrate the value of haplotype analysis as a robust approach for evaluating IL6 gene effects in association studies.

Identification of a novel regulatory region in the interleukin-6 gene promoter

Interleukin-6 (IL6) is an important pleiotropic cytokine that is regulated at the transcriptional level. To date, most work on its regulation has focused on a 1.2kb region 5' from the start of transcription, similar to published reports on other cytokine genes. This report demonstrates for the first time that a cytokine gene can be regulated by cis-acting regions much further upstream than previously examined. Comparative genomic analysis showed that a 120 kb region contains blocks of sequence conservation between human and rodent genomes, and that a 15 kb region proximal to the start of transcription contains 10 highly homologous sequence blocks of between 100 and 250 bp. By means of a reporter gene assay, a novel transcriptionally active region located between -5307 and -5202 bp upstream from the start of transcription was identified. Electrophoretic mobility shift assays showed nuclear protein(s) binding to this region, thus raising the possibility that the regulatory activity shown by the reporter gene constructs may be mediated by these proteins. These results suggest that the regulation of IL6 expression involves a much larger upstream region than previously examined and the control of IL6 transcription is likely to be regulated by a complex mechanism of modular cis-regulatory elements.

Association of interleukin-6 (IL-6) haplotypes with plaque-induced gingivitis in children

OBJECTIVES

The proinflammatory cytokine interleukin-6 (IL-6) is a key regulator of the host response to microbial infection and major modulator of extracellular matrix catabolism and bone resorption. The aim of this case-control study was to test differences between children with and without gingivitis in the distribution of IL-6 alleles at positions -174, -572, and -597 and their haplotypes.

MATERIAL AND METHODS

A total of 455 Caucasian children, aged 11 to 13 years, were enrolled in this study. According to gingival bleeding on probing indices, 183 were classified as healthy subjects and 272 as children with plaque-induced gingivitis. DNA for genetic analysis was obtained from buccal epithelial cells and PCR-RFLP methods were used for genotyping three selected IL-6 promoter polymorphisms.

RESULTS

Complex analysis revealed significant differences in haplotype frequencies between patients and healthy subjects (p<0.01). The CGA haplotype was significantly more frequent in children with gingivitis than in healthy subjects (41.5% versus 34.1%). In subanalyses, we found that IL-6 -174C allele was more frequent in patients (44.3%) than in healthy children (36.1%, p=0.016, P(corr)<0.05). Multivariate logistic regression analysis showed that allele C remained a risk factor for gingivitis in children (p=0.03) regardless of plaque or gender. However, the proportions of the IL-6 -597 and -572 genotypes were comparable between the two groups. CONCLUSIONS. Our results indicate that the three promoter polymorphisms in the IL-6 gene act in a cooperative fashion and suggest that IL-6 haplotypes could play a role in the pathogenesis of gingivitis in Caucasian children.

Association between interleukin-6 promoter haplotypes and aggressive periodontitis

BACKGROUND

Interleukin-6 (IL-6) polymorphisms have been shown to affect IL-6 promoter activity. This study investigated the possible role of IL-6 genetic polymorphisms and haplotypes in the predisposition to aggressive periodontitis (AgP).

MATERIAL AND METHODS

A case-control association study on 224 AgP patients and 231 healthy controls was performed in order to detect differences in genotype distributions of five single nucleotide polymorphisms (SNPs) located in the promoter region of the IL-6 gene.

RESULTS

The IL-6 -1363 polymorphism was associated with a diagnosis of AgP in subjects of all ethnicities (p=0.006, adjusted logistic regression). The -1480 SNP was associated with LAgP in subjects of all ethnicities (p=0.003). The -1480 and -6106 polymorphisms were associated with Localized AgP in Caucasians (n=24) (p=0.007 and 0.010, respectively). Haplotypes determined by the -1363 and -1480 polymorphisms were also associated with LAgP (p=0.001) in Caucasians.

CONCLUSIONS

This study supports the hypothesis of a link between IL-6 genetic factors and AgP and highlights the importance of two IL-6 polymorphisms (-1363 and -1480) in modulating disease phenotype and susceptibility.

Common studied polymorphisms do not affect plasma cytokine levels upon endotoxin exposure in humans

The aim of this study was to investigate to what extent single nucleotide polymorphisms (SNPs) in promoter regions of genes of Toll-like receptor (TLR)-4, tumour necrosis factor (TNF)-alpha, interleukin (IL)-18, interferon (IFN)-gamma, IL-6 and IL-10 affect the cytokine response during a controlled low-grade inflammatory response in vivo. Two hundred healthy young male volunteers were genotyped, and cytokine levels were measured in response to a low-dose intravenous bolus of Escherichia coli endotoxin. No association was detected between SNPs (TLR-4299, TLR-4399, TNF-308, IL-18-137, IL-18-607, IFN-gamma+874, IL-6-174, IL-10-592 and IL-10-1082) and endotoxin-induced changes in plasma levels of TNF-alpha, IL-6 and IL-10. IL-18 levels were unaffected by endotoxin. In conclusion, the investigated SNPs did not affect endotoxin-induced low-grade cytokine production of TNF-alpha, IL-6, IL-18 or IL-10 in healthy young men. Previous reports of a major heritability factor in the inflammatory response may be due to other target genes or effects in older age groups or women.

Thalidomide suppressed interleukin-6 but not tumor necrosis factor-alpha in volunteers with experimental endotoxemia

An early rationale for using thalidomide to treat erythema nodosum leprosum had been based on some reports that it suppresses tumor necrosis factor-alpha (TNF-alpha). However, in vivo and in vitro studies have yielded variable results, having shown that thalidomide can either enhance or suppress TNF-alpha. Since the course of circulating cytokines like TNF-alpha after infusion of endotoxin into volunteers is reproducible and characteristic, we investigated the effect of thalidomide on endotoxin-induced synthesis of TNF-alpha, interleukin (IL)-6, and IL-8. The cytokine response from 18 placebo-treated subjects who had undergone the endotoxin challenge were pooled with a placebo-treated subject from the current study and were compared with 4 subjects who received thalidomide (100 mg) every 6 h for 5 doses before endotoxin challenge. Thirty minutes after the last dose of thalidomide or placebo, volunteers were infused with 4-ng/kg endotoxin. Plasma was collected and assayed for cytokines by enzyme-linked immunosorbent assay. Endotoxin evoked the synthesis of the cytokines in all volunteers. The peak response for TNF-alpha was 1.5 h, 2.5 h for IL-8, and 3.0 h for IL-6. Thalidomide did not significantly delay the release of cytokines into the circulating blood. At the peak response, thalidomide reduced the concentration of the cytokines in the plasma. Using the area under the dose response curve (AUC(0 to 24) h), thalidomide reduced the AUC for IL-6 by 56%, for IL-8 by 30%, and TNF-alpha by 32%. In this model, thalidomide did not suppress TNF-alpha or IL-8, but it did suppress IL-6 at 4-h postinfusion with lipopolysaccharide (P=0.004), at 6 h (P=0.014), at 12 h (P=0.001), and at 16 h (P=0.012).

Interleukin-6 -174 promoter polymorphism does not influence IL-6 production after LPS and IL-1 beta stimulation in human umbilical cord vein endothelial cells

The IL-6 is a typical pleiotropic cytokine, which regulates T cell response, B cell differentiation and immunoglobulin production. Endothelial cells can produce large amounts of IL-6. SNP at position -174 (G/C) in the IL-6 promoter region was found to be associated with a series of complex diseases. In this study we analyzed whether IL-6 -174 G/C polymorphism has any effect on IL-6 production of in vitro cultured HUVECs. Thirty-three fresh umbilical cords were recruited from healthy pregnancies. The endothelial cells isolated from human umbilical cords were genotyped for IL-6 -174 SNP. C allele frequency was 0.379. The IL-6 production of each primary HUVEC line was measured after IL-1beta or LPS treatment by ELISA. Serial dilutions of the stimulating agents were applied and maximum amount of produced IL-6 (R(max)) and stimulator concentrations at half-maximal IL-6 response (MR(50)) were calculated for each of the cell lines. IL-6 production was not associated with IL-6 -174 SNP genotypes or with presence of C allele. Our results showed that IL-6 production of HUVEC after proinflammatory stimulation was not influenced by IL-6 -174 SNP. Further functional studies are required to compare differences and similarities in IL-6 -174 SNP dependent expression of IL-6 among various cell types.

Genetic association studies in VLBW infants exemplifying susceptibility to sepsis--recent findings and implications for future research

CONTEXT

In recent years, tremendous effort has been carried out to study the genetic basis of susceptibility to development, progression and severity of complex diseases and response to therapy. The ultimate goal of these investigations is to find new tools for prevention and treatment of these complex diseases, such as sepsis in very-low-birth-weight (VLBW) infants. VLBW cohorts have a restricted clinical risk profile for the development of sepsis including immaturity of immune functions and antenatal/perinatal risk factors but also a significant event rate of sepsis within a short period of observational time. Therefore, prospective VLBW cohorts are advantageous for the investigation of candidate genetic risk factors of sepsis compared to adult cohorts. Furthermore, environmental factors are much better documented and highly controlled for VLBW infants in a standardized NICU setting compared to adult cohorts which are influenced by a variety of environmental risk factors, e.g. habits and comorbidities.

OBJECTIVE

The aim of this review is to discuss the value and limitations of genetic association studies in VLBW infant cohorts exemplifying recent findings for genetic susceptibility to neonatal sepsis.

DATA SOURCE

Published Medline articles reporting on studies of associations between genetic polymorphisms, neonatal sepsis and septic shock in VLBW infants.

CONCLUSIONS

Up-to-date, the classical approach to investigate the genetic component of susceptibility to sepsis in VLBW infants by means of twin and concordance studies has not been implemented yet. Regarding the interpretation of data from current genetic association studies, one should be aware of significant differences in cohort size, study design and definition of cases, controls and clinical end points. Furthermore, the contribution of genetic variants to susceptibility to sepsis may be specifically influenced by the immaturity of the immune response in VLBW infants, the selectivity of responsiveness to certain pathogens and the genotopyic/phenotypic variability of pathogens. We provide implications for the conduct and evaluation of future association studies with particular reference to methodological quality standards.

Systemic inflammation in COPD: is genetic susceptibility a key factor?

COPD is a multicomponent disease characterized by abnormal inflammatory response of the lungs to noxious particles that is accompanied by systemic effects like weight loss, muscle wasting, reduced functional capacity and impaired health status. A persistent low-grade systemic inflammatory response reflected by enhanced levels of acute phase proteins like C-reactive protein (CRP) and pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, is present in part of the COPD population. The production of inflammatory proteins is partly genetically determined. Several studies have shown that polymorphisms within genes coding for these inflammatory mediators may modulate systemic inflammatory responses. Among all of these genes, the TNF family (TNF-alpha, lymphotoxin (LT)-alph and their receptors TNF-R55 and TNF-R75), interleukin (IL)-6 and CRP gene polymorphisms are the most prominent candidates. However, large carefully designed studies in well-characterized COPD cohorts are required to unravel the exact role of genetic background in the systemic component of this disease.

The fibrinogen −148 C/T polymorphism influences inflammatory response in experimental endotoxemia in vivo

INTRODUCTION

The acute phase reactant fibrinogen plays a critical role in the coagulation system and inflammation. Recently several polymorphisms have been described regulating basal and peak fibrinogen expression. We evaluated the role of a frequent promoter polymorphism in the beta chain of the fibrinogen gene (-148 C/T) in a human in vivo model of experimental endotoxemia.

MATERIAL AND METHODS

Healthy volunteers received 2 ng/kg endotoxin (LPS, n=73) as a bolus infusion over 2 min. Blood samples were collected by venipunctures into EDTA anticoagulated vacutainer tubes before LPS infusion. For determination of the fibrinogen promoter polymorphism, we developed a new mutagenic separated polymerase chain reaction assay.

RESULTS

Carriers of the -148 T allele had significantly lower TNFalpha expression throughout the whole time course of LPS stimulation and Interleukin-6 levels were trendwise lower, however only basal levels reached statistical significance. No effects were observed on markers of coagulation activation (D-Dimer, Prothrombin F(1+2)).

CONCLUSION

Our findings indicate, that the common -148 C/T polymorphism is associated with differences in the TNFalpha release in response to systemic LPS infusion in humans, and add to current evidence that gene-sequence changes in beta-fibrinogen locus can alter the ability of the host to respond to endotoxin.

IL6 G-174C associated with sudden infant death syndrome in a Caucasian Australian cohort

The aims of this study were to analyze IL6 G-174C in relation to high interleukin (IL)-6 concentrations found in some sudden infant death syndrome (SIDS) infants, and to assess the effects of IL6 G-174C, smoking status, and gender on IL-6 responses. SIDS infants, parents of SIDS infants, and populations with high (Aboriginal Australian), medium (Caucasian) or low (Bangladeshi) SIDS incidences were genotyped. Leukocytes were stimulated in vitro with endotoxin and IL-6 responses were assessed in relation to IL6 G-174C genotype, smoking status, and gender. The study findings showed that GG genotype, associated with high IL-6 responses, was predominant among Australian SIDS infants (58%) compared with control subjects (38%, p = 0.02), as well as Bangladeshis (94%) and Aboriginal Australians (88%) compared with Caucasians (42%, p < 0.01). GC smokers had higher median IL-6 responses (8.4 ng/ml(-1)) than GG (3.5 ng/ml(-1), p = 0.01) or CC smokers (2.4 ng/ml(-1), p < 0.01). GG nonsmokers had higher median IL-6 responses (4.9 ng/ml(-1)) than GG smokers (p < 0.05). Gender did not affect IL-6 responses. In conclusion, an association between IL6 G-174C and Australian SIDS infants was observed. IL6 G-174C alone cannot explain observed differences in the incidence of SIDS in the Bangladeshi and Aboriginal Australian populations. Further investigations are needed on interactions between smoking and gene polymorphisms in relation to proinflammatory responses implicated in SIDS.

Interleukin (IL)-12, IL-2, and IL-6 gene polymorphisms in Takayasu's arteritis from Turkey

Takayasu's arteritis (TA) is a chronic arterial inflammation of unknown etiology involving mainly the aorta and its major branches. Genetic polymorphisms of cytokines are screened as susceptibility factors for TA in Turkey. A total of 94 patients with TA were investigated for the genetic polymorphisms of the interleukin genes IL12, IL2,and IL6 and were compared with 108 healthy control subjects using polymerase chain reaction-sequence-specific primer method. The frequencies of IL12B 1188 C allele (p = 0.03, OR = 1.7) and CC genotype (p = 0.007, OR = 3.7) were both higher in TA patients than in control subjects. TT genotype at IL2-330 (p = 0.006, OR = 2.4) and GG genotype at IL6-174 (p = 0.04, OR = 1.9) were more frequent in TA patients. Lower prevalence of GT genotype at IL2-330 (p = 0.005, OR = 0.4), CG genotype at IL6-174 (p = 0.001, OR = 0.4), and AG genotypes at IL6-598 (p = 0.01, OR = 0.4) were also detected. The polymorphism of IL-12 as well as IL-6 and IL-2 genes may contribute to susceptibility and pathogenesis of TA by altering cytokine production and inducing inflammation.

Genetic susceptibility to neonatal infection

PURPOSE OF REVIEW

To review current data on genetic factors contributing to the striking susceptibility of neonates to infectious diseases and other adverse outcomes.

RECENT FINDINGS

Although few studies address genetic determinants of neonatal infectious disease susceptibility, several variants in genes involved in the innate immune response have been associated with differential risk for neonatal infection. The most consistent results relate to polymorphisms of tumour necrosis factor-alpha, whereas other gene polymorphisms, such as those of interleukin-6, have yielded conflicting findings. Similar genetic factors may be involved in other inflammatory neonatal diseases. Recent data suggest that genetic variation may influence the pace of immunologic maturation.

SUMMARY

Despite the enormous human and financial costs of infection for neonatal mortality and morbidity worldwide, it remains unclear why neonates are so susceptible. Genetic epidemiologic studies may assist in the identification of critical protective and pathogenic pathways. Despite the current relative lack of robust data, such studies are likely to facilitate the development of interventions that ultimately decrease the significant morbidity and mortality of this highly vulnerable population.

Interleukin-6-174-genotype, sepsis and cerebral injury in very low birth weight infants

We investigated the association between the interleukin 6 (IL-6)-174-genotype and unfavorable outcomes in preterm infants since it has been reported that the IL-6-174GG-genotype is associated with increased susceptibility to sepsis, and the IL-6-174CC-genotype is more common in preterm infants with severe intraventricular hemorrhage (IVH). We studied 1206 preterm infants with a birth weight below 1500 g. In contrast to previously published data, the frequency of IVH grade IV, periventricular leukomalacia, ventricular-peritoneal-shunting or death was not different between infants with different IL-6-genotypes: IL-6-174GG (n = 430) 8%, IL-6-174GC (n = 605) 9% and IL-6-174CC (n = 167) 12% (P = 0.2 for IL-6-174CC vs GG + GC). Furthermore, we were not able to confirm previously reported association between sepsis and the IL-6-174GG-genotype. Blood-culture-proven sepsis occurred in 19% of IL-6-174GG-carriers (n = 157), 26% of IL-6-174GC-carriers (n = 193) and 27% of infants carrying the IL-6-174CC-genotype (n = 67). We were not able to confirm previously reported associations between sepsis, cerebral injury and the IL-6-174-genotype in VLBW-infants.

Novel IL-6 haplotypes and disease association

Interleukin-6 (IL-6) is a pleiotropic cytokine crucial in both adaptive and innate immunity. Numerous genetic studies have shown association with variants of this gene in a multitude of diseases and phenotypes. Most tests of association have focused on a limited set of promoter polymorphisms, in particular, the -174G>C; however, there are many inconsistencies within and between these studies. We propose that there is a more complex regulatory haplotype extending further upstream of the previously characterised promoter region which will provide a more detailed view of the effect of variation on lL-6 regulation. We have exploited two additional single nucleotide polymorphisms (SNPs) in IL-6 that, when examined as a haplotype with existing markers, show an increased level of association with systemic onset juvenile arthritis in a family-based study. This suggests that the haplotype effect may be more functionally relevant to the disease.

Genetic Predisposition of the Interleukin-6 Response to Inflammation: Implications for a Variety of Major Diseases?

Background: A single-nucleotide polymorphism (SNP) in the promoter region of the interleukin-6 (IL-6) gene at position −174 (G&gt;C) has been reported to be associated with a variety of major diseases, such as Alzheimer disease, atherosclerosis, and cardiovascular disease, cancer, non-insulin-dependent diabetes mellitus, osteoporosis, sepsis, and systemic-onset juvenile chronic arthritis. However, authors of previous in vitro and in vivo studies have reported conflicting results regarding the functionality of this polymorphism. We therefore aimed to clarify the role of the −174 SNP for the induction of IL-6 in vivo.

Methods: We vaccinated 20 and 18 healthy individuals homozygous for the −174 C and G alleles, respectively, with 1 mL of Salmonella typhii vaccine. IL-1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured in the blood at baseline and up to 24 h after vaccination.

Results: Individuals with the G genotype had significantly higher plasma IL-6 values at 6, 8, and 10 h after vaccination than did individuals with the C genotype (P &lt;0.005). There were no differences between the two genotypes regarding serum concentrations of IL-1β and TNF-α before or after vaccination.

Conclusions: The −174 G&gt;C SNP in the promoter region of the IL-6 gene is functional in vivo with an increased inflammatory response associated with the G allele. Considering the central role of IL-6 in a variety of major diseases, the present finding might be of major relevance.

Simvastatin prevents vascular hyporeactivity during inflammation

BACKGROUND

There is growing evidence that statins exert anti-inflammatory and antioxidative vascular actions that are independent of lipid lowering. We tested whether hyporeactivity to the endothelium-dependent vasodilator acetylcholine (ACh) and the vasoconstrictor norepinephrine (NE) during acute experimental inflammation could be prevented by simvastatin.

METHODS AND RESULTS

In a randomized, placebo-controlled, parallel group study, forearm blood flow (FBF) responses to NE, ACh, and the endothelium-independent vasodilator nitroglycerin (NTG) were assessed at baseline, after 4 days of simvastatin 80 mg PO or placebo treatment, and during Escherichia coli endotoxin (lipopolysaccharide [LPS])-induced inflammation in 20 healthy volunteers. Additionally, markers of inflammation and neutrophil oxidative burst were assessed. Simvastatin and placebo had no effect on FBF or oxidative/inflammatory markers. LPS administration decreased the responses of FBF to NE by 43% (P<0.05) and decreased responses to ACh by 48% (P<0.05) but did not decrease FBF responses to NTG. Simvastatin completely preserved responses to NE and to ACh. The LPS-induced increases in neutrophil oxidative burst and plasma tumor necrosis factor-alpha concentrations were mitigated by simvastatin (P<0.05 versus placebo).

CONCLUSIONS

This study demonstrates potent vasoprotective properties of high-dose simvastatin during endotoxemia that may be useful for patients with acute systemic inflammation and associated vascular hyporeactivity.