Genetic polymorphisms within tumor necrosis factor gene promoter region: a role for susceptibility to ventilator-associated pneumonia

Relationship of preoperative Th1/Th2 ratio, TNF-α, and ALB with pulmonary infection in elderly patients after radical surgery for gastric cancer and predictive efficacy of a nomogram based on these factors

BACKGROUND

The immune system and the inflammatory response play an important role in the development of lung infections in the elderly population after radical gastric cancer surgery. Helper T cell 1 (Th1)/helper T cell 2 (Th2) phenotype reflects the dynamic immune homeostasis. Preoperative Th1/Th2 ratio and inflammatory response-related factors may have predictive value for postoperative lung infection.

AIM

To investigate the relationship of Th1/Th2 ratio, tumor necrosis factor-α (TNF-α), and albumin (ALB) with pulmonary infection in elderly patients after radical gastrectomy for gastric cancer and their predictive efficacy for postoperative pulmonary infection.

METHODS

A total of 135 patients with lung infection after radical gastric cancer surgery (infection group) and 135 uninfected patients (control group) admitted to our hospital from April 2020 to June 2022 were included in this study. The general demographic data, surgery-related conditions, combined diseases, and preoperative serum Th1/Th2 ratio, TNF-α, and ALB levels were compared between the two groups. R was used to draw a nomogram for predicting lung infection after radical gastrectomy in elderly patients, and the concordance index (C-index) of the nomogram was obtained to evaluate its prediction ability. The bootstrap method was used to draw the prediction curve, calibration curve, and ideal curve to evaluate the consistency between the nomogram and the actual observation results, and decision curve analysis (DCA) was performed to evaluate the clinical efficacy of the nomogram.

RESULTS

The infection group had longer operative time and postoperative gastric tube indwelling time, higher intraoperative bleeding, and more diabetic patients than the control group (P < 0.05). Preoperative Th1/Th2 ratio and ALB were lower and TNF-α was higher in the infection group than in the control group (P < 0.05). Binary logistic regression analysis showed that operative time, intraoperative bleeding, diabetes mellitus, postoperative gastric tube indwelling time, and TNF-α were risk factors for pulmonary infection in elderly patients after radical surgery for gastric cancer, and Th1/Th2 ratio and ALB were protective factors (P < 0.05). A nomogram for predicting postoperative pulmonary infection was developed, and its C-index reached 0.985, which was at a high level. External validation showed that the calibration degree of the nomogram was 0.826, and there was good agreement between the model and the actual observation. DCA showed that the nomogram had obvious positive net benefit and possessed good clinical utility in predicting postoperative infection.

CONCLUSION

Preoperative Th1/Th2 ratio, TNF-α, and ALB are associated with pulmonary infection in elderly patients after radical surgery for gastric cancer. The nomogram developed based on baseline correlation data with the above three indicators has good predictive ability and clinical utility, and can be used as a potential tool to predict postoperative infection and guide clinical management in the perioperative period.

The Role of Mid-Regional Proadrenomedullin in the Differential Diagnosis between Culture-Negative and Culture-Positive Sepsis at Emergency Department Admission

Background: The host response in culture-negative sepsis (CnS) has been marginally explored upon emergency department (ED) admission. It would be of paramount importance to create a clinical prediction rule to support the emergency department physician in identifying septic patients who can be treated with antibiotics immediately without waiting time to draw cultures if they are unlikely to provide useful diagnostic information. Methods: A multivariable logistic regression analysis was applied to identify the independent clinical variables and serum biomarkers of the culture-negative status among 773 undifferentiated septic patients. Those predictors were combined to build a nomogram predictive of CnS. Results: The serum concentrations of six biomarkers, among the eight biomarkers assayed in this study, were significantly lower in the patients with CnS (449) than in those with culture-positive sepsis (324). After correction for co-variates, only mid-regional proadrenomedullin (MR-proADM) was found to be independently correlated with culture-negative status. Absence of diabetes, hemoglobin concentrations, and respiratory source of infection were the other independent clinical variables integrated into the nomogram—its sensitivity and specificity for CnS were 0.80 and 0.79, respectively. Conclusions: Low concentrations of MR-proADM were independently associated with culture-negative sepsis. Our nomogram, based on the MR-proADM levels, did not predict culture-negative status with reasonable certainty in patients with a definitive diagnosis of sepsis at ED admission.

Combination of toothbrushing and chlorhexidine compared with exclusive use of chlorhexidine to reduce the risk of ventilator-associated pneumonia: A systematic review with meta-analysis

This study aimed to compare the effectiveness of 0.12% chlorhexidine alone and 0.12% chlorhexidine in combination with toothbrushing to prevent ventilator-associated pneumonia (VAP) in mechanically ventilated patients. The Embase, Latin American and Caribbean Health Science Literature, PubMed, Scientific Electronic Library Online, Scopus, LIVIVO, Web of Science, Cochrane Library, OpenThesis, and Open Access Thesis and Dissertations databases were used. Only randomized controlled trials without restrictions on the year or language of publication were included. Two reviewers assessed the risk of bias using the Joanna Briggs Institute Critical Appraisal Tool. A meta-analysis using a random-effects model estimated the combined relative risk (RR). The Grading of Recommendations, Assessment, Development and Evaluations approach was used to assess the certainty of the evidence. Initially, 2,337 studies were identified, of which 4 were considered in the systematic review and 3 in the meta-analysis (total sample: 796 patients). The studies were published between 2009 and 2017. All eligible studies had a low risk of bias. The meta-analysis revealed that the risk of VAP was 24% lower in patients receiving chlorhexidine combined with toothbrushing than in those receiving chlorhexidine alone (RR: 0.76; 95% confidence interval: 0.55-1.06), with moderate certainty of evidence and without statistical significance. In conclusion, considering the limitations of this study, a standard protocol for the prevention of VAP is not yet recommended. More studies with larger sample sizes are needed to draw strong conclusions. However, considering that toothbrushing is a simple intervention, it should be a common practice in mechanically ventilated patients, especially among patients with coronavirus disease.

Evaluation of TNF-α genetic polymorphisms as predictors for sepsis susceptibility and progression

Background

The goal of the study was to evaluate a potential role for tumor necrosis factor alpha (TNF-α) genetic variability as biomarker in sepsis. In particular, we aimed to determine if single nucleotide polymorphisms (SNPs) of TNF-α gene are associated with sepsis in terms of risk, severity and outcome.

Methods

We performed a prospective study on 163 adult critically ill septic patients (septic shock 65, sepsis 98, further divided in 40 survivors and 123 deceased) and 232 healthy controls. Genotyping of TNF-α SNPs (-308G/A, -238G/A, -376G/A and +489G/A) was performed for all patients and controls and plasma cytokine levels were measured during the first 24 h after sepsis onset.

Results

TNF-α +489G/A A-allele carriage was associated with significantly lower risk of developing sepsis and sepsis shock (AA+AG vs GG: OR = 0.53; p = 0.004; 95% CI = 0.34–0.82 and OR = 0.39; p = 0.003; 95% CI = 0.21–0.74, respectively) but not with sepsis-related outcomes. There was no significant association between any of the other TNF-α promoter SNPs, or their haplotype frequencies and sepsis or septic shock risk. Circulating TNF-α levels were higher in septic shock; they were not correlated with SNP genotype distribution; GG homozygosity for each polymorphism was correlated with higher TNF-α levels in septic shock.

Conclusions

TNF-α +489G/A SNP A-allele carriage may confer protection against sepsis and septic shock development but apparently does not influence sepsis-related mortality. Promoter TNF-α SNPs did not affect transcription and were not associated with distinct sepsis, septic shock risk or outcomes.

The role of Tumor necrosis factor alpha −308 G>A promoter polymorphism in pediatric community acquired pneumonia

Background

Tumor necrosis factor alpha (TNF-α) −308 G>A promoter polymorphism might be associated with excessive production of the proinflammatory cytokine TNF-α, modulating host response to pulmonary infections. Our objective was to evaluate the association of TNF-α gene −308 G>A polymorphism with susceptibility to, and severity of, community-acquired pneumonia (CAP).

Results

This was a cross-sectional study including 45 Egyptian children hospitalized for CAP in addition to 45 healthy children who served as a control group. Pneumonia severity was assessed on admission by the World Health Organization (WHO) guidelines; Pediatric Respiratory Severity Score (PRESS) score; Predisposition, Infection, Response and Organ failure (PIROm) score; and Respiratory Index of Severity in Children (RISC) score. Genotyping of TNF-α polymorphism was performed to all individuals by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Patients were monitored till hospital discharge. Frequency of AG genotype was lower among patients compared with control [odds ratio (OR) and 95% confidence interval (CI) = 0.13 (0.03–0.63); p = 0.012]. Prevalence of genotypes AA+AG was lower among patients compared with controls [OR and 95% CI = 0.34 (0.12–0.99); p = 0,048]. The “A” allele prevalence was higher among controls, but no significant association was found with CAP [OR and 95% CI = 0.58 (0.25–1.35); p = 0.21]. When PRESS score was used to classify patients into “severe pneumonia” and “non-severe pneumonia,” no significant association of any of the alleles or genotypes with CAP severity was found.

Conclusion

TNF-α −308 G>A polymorphism confers protection from pediatric CAP but is not associated with indicators of CAP severity. Larger studies are needed to confirm these findings in pediatric patients from different ethnicities.

Risk Factors of Ventilator-Associated Pneumonia in Critically III Patients

Ventilator-associated pneumonia (VAP), a hospital acquired pneumonia that occurs more than 48 h after mechanical ventilation, is a common complication of mechanical ventilation with a high mortality rate. VAP can cause patients to have difficulty weaning off the ventilator and to stay in the hospital longer, which results in a huge financial burden to patients and a huge demand for medical resources. Several strategies, such as drugs including chlorhexidine, β-lactam antibiotics and probiotics, have been used to prevent VAP in clinic. The incidence and the mortality rate of VAP have been decreased with the development of preventative strategies in the past decades, but VAP remains one of the most common causes of nosocomial infections and death in the intensive care unit. Current challenges in the management of VAP involved the lack of a gold standard for diagnosis, the absence of effective preventative strategies, and the rise in antibiotic resistance. Therefore, in order to reduce the incidence of VAP and improve the outcome of patients with mechanical ventilation, it is necessary to clarify the risk factors of VAP for clinical prevention and control of VAP. This paper reviews the international risk factors of VAP occurrence reported in recent years, including patient characteristics, increased mechanical ventilation time and prolonged length of hospital stay, disorders of consciousness, burns, comorbidities, prior antibiotic therapy, invasive operations, gene polymorphisms, and mentions the corresponding preventive measures. Each factor is not only an independent risk factor of VAP, but also has an influence on each other. A better understanding of risk factors for VAP is helpful for predicting the occurrence of VAP, improving the prevention and control of VAP, and reducing the morbidity and mortality rates of patients with VAP.

Haplotypes composed of minor frequency single nucleotide polymorphisms of the TNF gene protect from progression into sepsis: A study using the new sepsis classification

OBJECTIVES

Several articles have provided conflicting results regarding the role of single nucleotide polymorphisms (SNPs) in the promoter region of the TNF gene in susceptibility to sepsis. Former articles have been based on previous definitions of sepsis. This study investigated the influence of TNF haplotypes on the development of sepsis using the new Sepsis-3 definitions.

METHODS

DNA was isolated from patients suffering from infection and systemic inflammatory response syndrome. Haplotyping was performed for six SNPs of TNF. The serum levels of tumour necrosis factor alpha (TNF-α) of these patients were measured using an enzyme immunosorbent assay. Patients were classified into infection and sepsis categories using the Sepsis-3 definitions. Associations between the TNF haplotypes and the clinical characteristics and serum TNF-α levels of the patients were examined.

RESULTS

The most common TNF haplotype h1 was composed of major alleles of the studied SNPs. Carriage of haplotypes composed of minor frequency alleles was associated with a lower risk of developing sepsis (odds ratio 0.41, 95% confidence interval 0.19-0.88, p=0.022), but this did not affect the 28-day outcome. Serum TNF-α levels were significantly higher among patients homozygous for h1 haplotypes who developed sepsis compared to infection (p=0.032); a similar result was not observed for patients carrying other haplotypes.

CONCLUSIONS

Haplotypes containing minor frequency SNP alleles of TNF protect against the development of sepsis without affecting the outcome.

The role of genetics and antibodies in sepsis

During the course of sepsis when immunosuppression predominates, the concentrations of circulating immunoglobulins (IGs) are decreased and this is associated with adverse outcomes. The production of IGs as response to invasive bacterial pathogens takes place through a complex pathway starting from the recognition of the antigen (Ag) by innate immune cells that process and present Ags to T cells. The orchestration of T-helper (Th) lymphocyte responses directs specific B cells and ends with the production of IGs by plasma cells. All molecules implicated in this process are encoded by genes bearing single nucleotide polymorphisms (SNPs). Meta-analysis of case-control studies have shown that the carriage of minor frequency SNPs of CD14, TLR2 and TNF is associated with increased sepsis risk. The ambiguity of results of clinical trials studying the clinical efficacy of exogenous IG administration in sepsis suggests that efficacy of treatment should be considered after adjustment for SNPs of all implicated genes in the pathway of IG production.

Variation in Inflammatory Response during Pneumococcal Infection Is Influenced by Host-Pathogen Interactions but Associated with Animal Survival

Inflammation is a crucial part of innate immune responses but, if imbalanced, can lead to serious clinical conditions or even death. Cytokines regulate inflammation, and studies report their impact on clinical outcome. However, host and pathogen genetic backgrounds influence cytokine production, making it difficult to evaluate which inflammatory profiles (if any) relate to improved prognosis.Streptococcus pneumonia is a common human pathogen associated with asymptomatic nasopharyngeal carriage. Infrequently, it can lead to a wide range of diseases with high morbidity and mortality rates. Studies show that both pneumococcal serotype and host genetic background affect the development of disease and contribute to variation in inflammatory responses. In this study, we investigated the impact of the host and pneumococcal genetic backgrounds on pulmonary cytokine responses and their relationship to animal survival. Two inbred mouse strains, BALB/c and CBA/Ca, were infected with 10 pneumococcal strains, and the concentrations of six pulmonary cytokines were measured at 6 h and 24 h postinfection. Collected data were analyzed by principal-component analysis to identify whether there is any pattern in the observed cytokine variation. Our results show that host-pneumococcus combination was at the core of observed variation in cytokine responses, yet the resulting cytokine profile discriminated only between survivors and fatalities but not mouse or pneumococcal strains used during infection. Therefore, our results indicate that although alternative inflammatory profiles are generated during pneumococcal infection, a common pattern emerged, which determined the clinical outcome of pneumococcal infections.

Genetic susceptibility to nosocomial pneumonia, acute respiratory distress syndrome and poor outcome in patients at risk of critical illness

Genetic susceptibility may partially explain the clinical variability observed during the course of similar infections. To establish the contribution of genetic host factors in the susceptibility to critical illness, we genotyped 750 subjects (419 at high risk of critical illness) for 14 single nucleotide polymorphisms (SNPs) in the xenobiotics detoxification/oxidative stress and vascular homeostasis metabolic pathways. In the group of nosocomial pneumonia (NP; 268 patients) the risk of acute respiratory distress syndrome (ARDS) is significantly higher for the carriers of CYP1A1 rs2606345 T/T genotypes and AhR rs2066853 G/A-A/A genotypes. AGTR1 rs5186 allele C is more common among NP non-survivors. The duration of stay in intensive care units (ICU) is higher for NP patients with ABCB1 rs1045642-T allele. The cumulative effect of the risk alleles in the genes comprising two sets of genes partners (xenobiotics detoxification: CYP1A1, AhR and RAS family: ACE, AGT, AGTR1) is associated with the development of both NP and ARDS.

The beginning of personalized medicine in sepsis: small steps to a bright future

There is a growing recognition that there is a need for a more personalized approach towards sepsis care. In most clinical trials investigating novel therapeutic interventions against sepsis, patients have been considered a rather homogeneous population. However, there is probably more individual variability between septic patients than previously considered. The pathophysiology of sepsis is a complex and dynamic process that originates from the host immune response to infection and varies according to the genetic predisposition, immune status and co-morbid conditions of the host, the type of pathogen and the site and extent of infection. Until now, efforts to stratify septic patients according to their immune profile were hampered by the lack of specific biomarkers. Recent advances in molecular medicine have made it possible to develop tools that will facilitate a faster and more precise diagnosis of infection. Individual variability between each patient's responses to infection can assist in tailoring therapeutic interventions to the individual's disease profile and monitoring treatment response. In this review, we describe those recent advances in genomics and theragnostics, which are slowly entering clinical practice and which will make possible a more personalized approach to each septic patient in the next decade.

Impact of TNF haplotypes in the physical course of acne vulgaris

BACKGROUND

The role of single-nucleotide polymorphisms (SNPs) of the TNF gene in acne vulgaris remains controversial.

METHODS

Genomic DNA was isolated from 185 patients with acne vulgaris and 165 healthy controls. SNPs at positions -376, -308 and -238 of the promoter region of TNF were defined.

RESULTS

The frequency of the GAG haplotype was greater among patients (16.8%) than among controls with borderline significance (9.7%, p = 0.059). Male carriers of haplotypes other than GGG presented acne vulgaris at a later age than carriers of the GGG haplotype. No effect of the GAG haplotype on the frequency of acne conglobata was found among women with polycystic ovary syndrome.

CONCLUSIONS

Carriage of the GAG haplotype of TNF is linked with borderline susceptibility to acne vulgaris. The GGG haplotype is related with earlier disease onset in male patients.

Impact of haplotypes of TNF in the natural course of infective endocarditis

Based on previous findings for the role of single nucleotide polymorphisms (SNPs) of TNF for the predisposition for bloodstream infections, this study investigates the role of these SNPs at the promoter positions -376, -308, -238 in infective endocarditis (IE). In a case-control study, 83 patients with IE and 83 controls were enrolled. Blood genotyping for the presence of G or A alleles of the three SNPs was carried out using restriction fragment length polymorphisms. Haplotypes were calculated. Patients were mostly infected by Staphylococcus aureus (32.5%) and by species of enterococci (14.3%) and streptococci (14.3%). Carriage of the minor frequency A alleles at -238 of the promoter region of TNF was greater than in controls (8.4% versus 1.2%, p 0.003). The presence of any of the three GGA/GAA/AGA haplotypes was more frequent in patients with IE (OR 8.22, 95CI% 1.8-37.4, p 0.001). After multivariate logistic regression analysis, it was found that the only factor related to fatal outcome was carriage of the wild-type GGG haplotype (OR, 3.29, 95CI%, 1.05-10.29, p 0.04). GGA, AGA and GAA haplotypes were more frequent in patients with IE than in controls, suggesting a predisposition for IE and a potential protective role against fatal outcome, as the wild-type GGG haplotype was independently related with death.

The complex pathogenesis of bacteremia: from antimicrobial clearance mechanisms to the genetic background of the host

Bacteremia develops when bacteria manage to escape the host immune mechanisms or when the otherwise well-orchestrated immune response fails to control bacterial spread due to inherent or acquired immune defects that are associated with susceptibility to infection. The pathogenesis of bacteremia has some characteristic features that are influenced by the genetic signature of the host. In this review, the host defense mechanisms that help prevent bacteremia will be described and the populations who are at risk because of congenital or acquired deficiencies in such mechanisms will be defined. A special mention will be made to novel insights regarding host immune defense against the most commonly isolated organisms from patients with community-acquired bloodstream infections.

Associations between TNF-α polymorphisms and pneumonia: a meta-analysis

BACKGROUND

Several studies evaluated the associations of tumor necrosis factor-α (TNF-α) polymorphisms with pneumonia in different populations. However, the results were conflicting and controversial.

METHODS

Databases including PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Data were extracted independently by two investigators. Crude odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated.

RESULTS

Twelve case-control studies and one cohort study were included. Overall, no association between TNF-α -308A/G polymorphism and pneumonia risk was observed for AA +AG vs. GG (OR = 1.13; 95% CI 0.99-1.30; P = 0.07). In addition, TNF-α -308A/G polymorphism was not associated with pneumonia mortality (OR = 1.96; 95% CI 0.94-4.09; P = 0.07). Furthermore, there was no association of TNF-α -238A/G polymorphism with the risk of pneumonia (OR = 1.38; 95% CI 0.84-2.28; P = 0.20).

CONCLUSIONS

TNF-α -308A/G, -238A/G polymorphisms were not associated with pneumonia risk. Moreover, TNF-α -308A/G polymorphism did not play a role in the pneumonia mortality risk.