Influence of genetic variations in TLR4 and TIRAP/Mal on the course of sepsis and pneumonia and cytokine release: an observational study in three cohorts

Introduction: It has been proposed that individual genetic variation contributes to the course of severe infections and sepsis. Recent studies of single nucleotide polymorphisms (SNPs) within the endotoxin receptor and its signaling system showed an association with the risk of disease development. This study aims to examine the response associated with genetic variations of TLR4, the receptor for bacterial LPS, and a central intracellular signal transducer (TIRAP/Mal) on cytokine release and for susceptibility and course of severe hospital acquired infections in distinct patient populations. Methods: Three intensive care units in tertiary care university hospitals in Greece and Germany participated. 375 and 415 postoperative patients and 159 patients with ventilator associated pneumonia (VAP) were included. TLR4 and TIRAP/Mal polymorphisms in 375 general surgical patients were associated with risk of infection, clinical course and outcome. In two prospective studies, 415 patients following cardiac surgery and 159 patients with newly diagnosed VAP predominantly caused by Gram-negative bacteria were studied for cytokine levels in-vivo and after ex-vivo monocyte stimulation and clinical course. Results: Patients simultaneously carrying polymorphisms in TIRAP/Mal and TLR4 and patients homozygous for the TIRAP/Mal SNP had a significantly higher risk of severe infections after surgery (odds ratio (OR) 5.5; confidence interval (CI): 1.34 - 22.64; P = 0.02 and OR: 7.3; CI: 1.89 - 28.50; P < 0.01 respectively). Additionally we found significantly lower circulating cytokine levels in double-mutant individuals with ventilator associated pneumonia and reduced cytokine production in an ex-vivo monocyte stimulation assay, but this difference was not apparent in TIRAP/Mal-homozygous patients. In cardiac surgery patients without infection, the cytokine release profiles were not changed when comparing different genotypes. Conclusions: Carriers of mutations in sequential components of the TLR signaling system may have an increased risk for severe infections. Patients with this genotype showed a decrease in cytokine release when infected which was not apparent in patients with sterile inflammation following cardiac surgery

Changes of the secretory capacity of monocytes between patiens with sepsis, severe sepsis and septic shock

AIM OF THE STUDY: The present study aimed to investigate changes of the secretory capacity of monocytes between patients with sepsis, severe sepsis and septic shock due to ventilator-associated pneumonia (VAP). METHODS: Peripheral venous blood was sampled from 100 patients with VAP for seven consecutive days. 25 patients suffered from sepsis, 28 from severe sepsis and 47 from septic shock. All patients were well-matched for severity, age and sex. Blood monocytes were isolated and cultured without /with purified endotoxin (lipopolysaccharide (LPS)). Estimation of tumour necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) in cultures' supernatants was performed by an enzyme immunoassay. RESULTS: TNF alpha secretion, on day 1, was higher after stimulation of monocytes with LPS, but this finding was statistically significant only in patients with septic shock. Higher IL-6 levels were measured in patients suffering from sepsis, after exposure to LPS, on day 1. TNFalpha and IL-6 production from LPS-stimulated monocytes was lower in non survivors compared to survivors, but the difference was not statistically significant. CONCLUSIONS: Diminished cytokine levels from monocytes of critically ill patients remain low after stimulation with LPS ex vivo, a phenomenon that contributes to immunosuppresion and mortality.ΣΚΟΠΟΣ ΤΗΣ ΜΕΛΕΤΗΣ: Σκοπός της παρούσας μελέτης είναι να τεκμηριωθούν ενδεχόμενες μεταβολές της εκκριτικής ικανότητας των μονοκυττάρων σε κυτταροκίνες, μετά τη διέγερσή τους με βακτηριακά προϊόντα κατά την πρόοδο της σηπτικής διεργασίας. ΑΣΘΕΝΕΙΣ - ΜΕΘΟΔΟΙ: Εκατό ασθενείς με πνευμονία συνδεόμενη με το μηχανικό αερισμό και σήψη, σοβαρή σήψη ή σηπτική καταπληξία συμμετείχαν σε μια προοπτικού τύπου μελέτη. Εβδομήντα τρεις ασθενείς ήταν άνδρες και εικοσιεπτά ασθενείς ήταν γυναίκες. 25 ασθενείς έπασχαν από σήψη, 28 από σοβαρή σήψη και 47 από σηπτική καταπληξία. Δεν υπήρχε στατιστικά σημαντική διαφορά στις τρεις κατηγορίες ασθενών (σήψη, σοβαρή σήψη, σηπτική καταπληξία) όσον αφορά την ηλικία, το φύλο και τη βαρύτητα της νόσου (APACHE II) και τη θνητότητα. Σε όλους τους ασθενείς απομονώθηκαν τα μονοκύτταρα του περιφερικού αίματος για επτά συνεχόμενες ημέρες και ακολούθως επωάσθηκαν παρουσία/απουσία ενδοτοξίνης. Προσδιορίστηκαν τα επίπεδα TNF-α και IL-6 στα υπερκείμενα των μονοκυττάρων με ανοσοενζυμική μέθοδο Elisa. ΑΠΟΤΕΛΕΣΜΑΤΑ: Η παραγωγή TNF-α, την ημέρα 1, ήταν υψηλότερη μετά τη διέγερση με ενδοτοξίνη σε όλες τις ομάδες ασθενών. Το εύρημα αυτό όμως ήταν στατιστικά σημαντικό μόνο στους πάσχοντες από σηπτική καταπληξία. Αντίστοιχα, την πρώτη ημέρα παρακολούθησης υψηλότερα επίπεδα IL-6, μετά τη διέγερση με LPS, παράχθηκαν από τα μονοκύτταρα της ομάδας σήψης. Η παραγωγή TNF-α και IL-6, μετά τη δέγερση με LPS, ήταν ελαττωμένη στους ασθενείς που απεβίωσαν συγκριτικά με εκείνους που έζησαν. Συμπερασμα: h παραγωγή των κυτταροκινών από τα μονοκύτταρα βαρέως πασχόντων ασθενών παραμένει ελαττωμένη μετά τη διέγερση με LPS, με αποτέλεσμα αδυναμία επαρκούς ανοσορύθμισης, γεγονός το οποίο μπορεί να συμβάλλει στην αύξηση της θνητότητας

Influence of genetic variations in TLR4 and TIRAP/Mal on the course of sepsis and pneumonia and cytokine release: An observational study in three cohorts

Introduction: It has been proposed that individual genetic variation contributes to the course of severe infections and sepsis. Recent studies of single nucleotide polymorphisms (SNPs) within the endotoxin receptor and its signaling system showed an association with the risk of disease development. This study aims to examine the response associated with genetic variations of TLR4, the receptor for bacterial LPS, and a central intracellular signal transducer (TIRAP/Mal) on cytokine release and for susceptibility and course of severe hospital acquired infections in distinct patient populations.Methods: Three intensive care units in tertiary care university hospitals in Greece and Germany participated. 375 and 415 postoperative patients and 159 patients with ventilator associated pneumonia (VAP) were included. TLR4 and TIRAP/Mal polymorphisms in 375 general surgical patients were associated with risk of infection, clinical course and outcome. In two prospective studies, 415 patients following cardiac surgery and 159 patients with newly diagnosed VAP predominantly caused by Gram-negative bacteria were studied for cytokine levels in-vivo and after ex-vivo monocyte stimulation and clinical course.Results: Patients simultaneously carrying polymorphisms in TIRAP/Mal and TLR4 and patients homozygous for the TIRAP/Mal SNP had a significantly higher risk of severe infections after surgery (odds ratio (OR) 5.5; confidence interval (CI): 1.34 - 22.64; P = 0.02 and OR: 7.3; CI: 1.89 - 28.50; P < 0.01 respectively). Additionally we found significantly lower circulating cytokine levels in double-mutant individuals with ventilator associated pneumonia and reduced cytokine production in an ex-vivo monocyte stimulation assay, but this difference was not apparent in TIRAP/Mal-homozygous patients. In cardiac surgery patients without infection, the cytokine release profiles were not changed when comparing different genotypes.Conclusions: Carriers of mutations in sequential components of the TLR signaling system may have an increased risk for severe infections. Patients with this genotype showed a decrease in cytokine release when infected which was not apparent in patients with sterile inflammation following cardiac surgery