Human toll-like receptor 4 (hTLR4) and CD14 are known to be components of the lipopolysaccharide receptor complex. Our study investigated the association between TLR4 mutations (Asp299Gly and Thr399Ile) and CD14 polymorphism(s) with outcome in an intensive care unit (ICU) population at risk for sepsis. By use of a polymerase chain reaction-based restriction fragment-length polymorphism analysis technique, the hTLR4 gene was altered in 14 (18%) of 77 ICU patients (all positive for systemic inflammatory response syndrome) and in 5 (13%) of 39 volunteers. There was a significantly higher incidence of gram-negative infection among patients with the mutations (11 [79%] of 14), compared with that in the wild-type population (11 [17%] of 63; P=.004). No association between CD14 polymorphism(s) and the incidence of infection or outcome was observed. These findings indicate that hTLR4 mutations are associated with an increased incidence of gram-negative infections in critically ill patients in a surgical setting.

Short-term preexposure of mononuclear cells to epinephrine inhibits LPS-induced production of TNF, whereas preexposure for 24 h results in increased TNF production. To assess the effects of epinephrine infusions of varying duration on in vivo responses to LPS, the following experiments were performed: ( a ) Blood obtained from eight subjects at 4-24 h after the start of a 24-h infusion of epinephrine (30 ng/kg per min) produced less TNF after ex vivo stimulation with LPS compared with blood drawn before the start of the infusion, and ( b ) 17 healthy men who were receiving a continuous infusion of epinephrine (30 ng/kg per min) started either 3 h (EPI-3; n ϭ 5) or 24 h (EPI-24; n ϭ 6) before LPS injection or an infusion of normal saline (LPS; n ϭ 6) were studied after intravenous injection of LPS (2 ng/kg, lot EC-5). EPI-3 inhibited LPS-induced in vivo TNF appearance and also increased IL-10 release (both P Ͻ 0.005 versus LPS), whereas EPI-24 only attenuated TNF secretion ( P ϭ 0.05). In separate in vitro experiments in whole blood, epinephrine increased LPS-induced IL-10 release by a combined effect on ␣ and ␤ adrenergic receptors. Further, in LPS-stimulated blood, the increase in IL-10 levels caused by epinephrine only marginally contributed to concurrent inhibition of TNF production. Epinephrine, either endogenously produced or administered as a component of sepsis treatment, may have a net antiinflammatory effect on the cytokine network early in the course of systemic infection. ( J. Clin. Invest. 1996. 97:713-719.)

Background The genetic determinants of the human innate immune response are poorly understood. Apolipoprotein (apo)E, a lipid-trafficking protein that impacts inflammation, has well-described ‘wild type’ (ε3) and disease-associated (ε2, ε4) alleles, but its connection to human innate immunity is undefined. Objective To define the relationship of APOε4 to the human innate immune response. Methods We evaluated APOε4 in several functional models of the human innate immune response including intravenous lipopolysaccharide challenge in human subjects, and assessed APOε4 association to organ injury in human severe sepsis, a disease driven by dysregulated innate immunity. Results Whole blood from healthy APOε3/APOε4 volunteers induced higher cytokines upon ex vivo stimulation with Toll like Receptor (TLR)2, TLR4, or TLR5 ligands than blood from APOε3/APOε3 subjects, whereas TLR7/8 responses were similar. This was associated with increased lipid rafts in APOε3/APOε4 monocytes. By contrast, APOε3/APOε3 and APOε3/APOε4 serum neutralized lipopolysaccharide equivalently and supported similar lipopolysaccharide responses in Apoe-deficient macrophages, arguing against a differential role for secretory APOE4 protein. After intravenous lipopolysaccharide, APOε3/APOε4 human subjects had higher hyperthermia and plasma TNFα and earlier plasma IL-6 than APOε3/APOε3 subjects. APOE4-targeted replacement mice displayed enhanced hypothermia, plasma cytokines, and hepatic injury, and altered splenic lymphocyte apoptosis after systemic lipopolysaccharide compared with APOE3 counterparts. In a cohort of 828 severe sepsis patients, APOε4 was associated with increased coagulation system failure among European American subjects. Conclusions APOε4 is a determinant of the human innate immune response to multiple TLR ligands, and associates with altered patterns of organ injury in human sepsis.

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Objectives The intravenous administration of a bolus dose of endotoxin to healthy human subjects triggers acute systemic inflammatory responses that include cytokine production and dynamic changes in gene expression in peripheral blood leukocytes (PBL). This study sought to determine the state of clock gene expression in human PBL, and leukocytes subpopulations, challenged with in vivo endotoxin at two circadian/diurnal phases of the clock. Design Clinical and laboratory investigation. Setting University-based research laboratory and clinical research center Subjects Human volunteers. Interventions Human subjects were administered a standard dose of endotoxin (2ng/kg) or saline at either 09:00 or 21:00 h. Blood samples were collected at selected time points pre- and post-infusion. Measurements and Mains results Clock gene expression was determined in human PBL, neutrophils, and monocytes, by quantitative real-time polymerase chain reaction. The fold change for each gene was determined using the 2(-ΔΔCt) method. We show that endotoxin causes profound suppression of circadian clock gene expression, clearly manifested in human PBL, neutrophils, and monocytes. Clock, Cry1-2, Per3, CSNK1ε, Rora and Rev-erb gene expression were all reduced by 80-90% with the nadir between 3 to 6 hours post-infusion. Per1 and Per2 reached an expression nadir between 13 and 17 hours post-infusion. The levels of plasma interleukin-6 and tumor necrosis factor peaked and then returned to baseline within 6 hours. In contrast, clock gene expression remained suppressed for up to 17 hours, irrespective of the phase of the clock at the time of the endotoxin challenge. Endotoxin did not perturb the melatonin secretory rhythm. Conclusions Circadian clock gene expression in PBL is dramatically altered, and possibly uncoupled from the activity of the central clock, during periods of acute systemic inflammation. The realignment of the central and peripheral clocks may constitute a previously unappreciated key factor affecting recovery from disease in humans.