Circulating interleukin-1 and tumor necrosis factor in septic shock and experimental endotoxin fever

Interleukins (IL) -1 beta and -1 alpha and tumor necrosis factor (TNF-alpha) were measured by radioimmunoassay in plasma samples from 44 healthy individuals, 15 patients in septic shock, and 6 volunteers infused with endotoxin. Plasma IL-1 alpha levels were low (40 pg/ml) or undetectable in all situations. In 67% of the healthy subjects, plasma IL-1 beta levels were less than 70 pg/ml. Septic patients had higher plasma IL-1 beta levels (120 +/- 17 pg/ml, P = .001); those of surviving patients were higher than those of patients who died (P = .05). Plasma TNF-alpha concentrations in septic individuals were elevated (119 +/- 30 pg/ml) and correlated with severity of illness (r = .73, P = .003), but no correlation was observed between plasma IL-1 beta and TNF-alpha concentrations in individual samples. Infusion of endotoxin caused a twofold elevation of IL-1 beta, from a baseline of 35 +/- 5 pg/ml to a maximum of 69 +/- 27 pg/ml at 180 min (P less than .05). Peak TNF-alpha levels after endotoxin infusion were 15 times higher than IL-1 beta levels, were attained more rapidly (90 min), and as with the septic patients, did not correlate with IL-1 beta levels. These data support the concept that plasma IL-1 beta and TNF-alpha concentrations are regulated independently and are associated with different clinical outcomes.     

Interleukin-6 (IL-6) as an anti-inflammatory cytokine: induction of circulating IL-1 receptor antagonist and soluble tumor necrosis factor receptor p55

The aim of this study was to investigate whether interleukin (IL)-6 induces the production of IL-1 and tumor necrosis factor (TNF) antagonists. Serial plasma samples were obtained from cancer patients participating in phase I and II trials of recombinant IL-6 administered as a 120-hour continuous intravenous (IV) infusion. Plasma IL-1 receptor antagonist (IL-1Ra) and soluble TNF receptor p55 (TNFsRp55) levels were measured by specific radioimmunoassays (RIAs). IL-1Ra levels increased rapidly, reaching peak values (9.6 +/- 1.7 ng/mL) within 2 to 4 hours of beginning treatment. Thereafter, levels promptly declined, reaching near baseline within 24 hours despite continuation of IL-6. TNFsRp55 plasma levels increased within 4 to 8 hours after initiating treatment and increased progressively throughout the duration of therapy. IL-1 beta and TNF-alpha plasma levels were below the detection limit in all samples tested. Peripheral blood mononuclear cells (PBMC) exposed to IL-6 produced only small amounts (1.56 +/- 0.3 ng/mL) of IL-1Ra, even in the presence of exogenous soluble IL-6 receptor (gp80). TNFsRp55 levels measured in the supernatants of IL-6- stimulated PBMC were below the detection limit of the assay. Macrophages generated by culturing monocytes in granulocyte-macrophage colony-stimulating factor (GM-CSF) were much more responsive to IL-6 than freshly isolated unfractionated or adherent PBMC and synthesized almost as much IL-1Ra when stimulated with IL-6 as with endotoxin. These results suggest that the antinflammatory properties of IL-6 may be due; in part, to the induction of IL-1Ra synthesis and the release of soluble TNF receptors. Our findings also suggest that tissue macrophages may be an important source of IL-6-induced IL-1Ra.     

Leukocyte activation and cytokine production during experimental human endotoxemia

Background: At present, it is unclear whether in experimental endotoxemia, the pro-inflammatory response observed in healthy volunteers is followed by an anti-inflammatory response, as observed in patients with sepsis. We studied the evolution of a number of inflammatory parameters during a prolonged period (24 h) after infusion of endotoxin in healthy subjects. Methods: Six healthy male subjects received an infusion of endotoxin (4 ng/kg body weight). Blood was drawn before, and at various intervals up to and including 24 h after, endotoxin infusion. Circulating cytokine levels, leukocyte activation surface markers, plasma lactoferrin, and neopterin levels were measured, and clinical signs and symptoms were noted during a 24-h period. Monocyte and neutrophil activation after endotoxin infusion is investigated in relation to the inflammatory response. The extent of neutrophil and monocyte activation was correlated to clinical markers and blood levels of inflammatory mediators and cytokines. Results: Tumor necrosis factor-alpha appeared 30 min after infusion in the circulation, peaking (5665+/-1910 pg/ml) at 2 h. Interleukin-10 appeared 60 min after infusion, peaking (427+/-348 pg/ml) at 3 h. The expression of leukocyte activation markers increased significantly after infusion. Expression of HLA-DR on monocytes decreased significantly after 3 h (P=0.03). There was a correlation between the TNF-alpha:IL-10 ratio and the CD11b:HLA-DR ratio (P=0.03). Conclusions: During experimental human endotoxemia, an initial pro-inflammatory response is successfully compensated by an anti-inflammatory response, leading to homeostasis. This is in contrast to what happens in septic patients with compensatory anti-inflammatory response syndrome. The inflammatory balance, expressed as the cytokine pro:anti-inflammatory ratio, is reflected at a cellular level.     

Melanocortin modulation of inflammatory cytokine and neuroendocrine responses to endotoxin in the monkey

alpha-MSH has potent antiinflammatory properties, but little is known about the specific melanocortin receptors (MC-Rs) that mediate these effects or about the role of the melanocortin system in modulating cytokine responses to an inflammatory challenge in the primate in vivo. We, therefore, studied the effects of infusion of the alpha-MSH agonist, [Nle(4),d-Phe(7)]-alpha-MSH (NDP-MSH); the alpha-MSH antagonist, SHU9119; and the selective MC3-R agonist, D-Trp8-gamma-MSH, compared with saline, on proinflammatory cytokine (TNF-alpha, IL-1beta, and IL-6), antiinflammatory cytokine [IL-10 and IL-1 receptor antagonist (IL-1ra)], and pituitary-adrenal responses to endotoxin in ovariectomized monkeys. In the first study NDP-MSH or SHU9119 was infused iv for 7 h starting at 0800 h, endotoxin was injected at 1000 h, and serial blood samples were collected (n = 6). NDP-MSH significantly attenuated proinflammatory cytokine responses to endotoxin. The area under the response curve (AUC) decreased by 61% for TNF-alpha (P = 0.02), 47% for IL-1beta (P = 0.02), and 41% for IL-6 (P = 0.04); there was no effect on IL-1ra or IL-10. SHU9119 did not affect proinflammatory cytokine responses, but decreased the IL-10 response by 31% (P = 0.03). NDP-MSH also attenuated ACTH (P < 0.001) and cortisol (P = 0.02) responses. In a second study, the effects of d-Trp8-gamma-MSH were similarly examined in seven monkeys. The AUC for IL-6 was decreased by 37% (P = 0.04) by d-Trp8-gamma-MSH; the AUC for IL-10 was increased by 22%, but this was not significant. However, the ratio of IL-6 to IL-10 was significantly decreased by d-Trp8-gamma-MSH (P = 0.04), consistent with a relatively more antiinflammatory cytokine environment. These results indicate that NDP-MSH can attenuate proinflammatory cytokine responses in the primate, consistent with previous studies in the rodent, and provide new evidence for a role for MC3-R in this process. Moreover, they show for the first time that SHU9119, a mixed MC3/4-R antagonist, can decrease the IL-10 response, establishing a physiological role for endogenous MSH in modulating the release of an antiinflammatory cytokine.     

Protein restriction and dexamethasone as a model of protein hypercatabolism in dogs: effect of glutamine on leucine turnover

To determine (1) whether protein restriction, combined with glucocorticosteroid treatment, can be used as a hypercatabolic model and (2) if so, whether glutamine attenuates protein wasting in this model, the effects of protein restriction, dexamethasone, and glutamine on leucine metabolism were assessed in dogs. A control group (n = 8) received a maintenance diet; another group (n = 8) received a protein-restricted diet either (1) alone; (2) along with a 7-day corticoid treatment; or (3) along with a 7-day corticoid treatment and a 7-hour intravenous (IV) glutamine infusion. The last day of each regimen, dogs underwent an IV isotope infusion in the fasting state, with a 3-hour NaH(13)CO3 infusion to assess CO2 production, and immediately thereafter, a 3-hour (13)C-leucine infusion to assess leucine appearance rate (Ra), oxidation (Ox), and nonoxidative leucine disposal (NOLD), expressed as micromol x kg(-1) x h(-1). Protein restriction was associated with a 24% decline in leucine Ra (223 +/- 16 v 298 +/- 17; P <.01), an index of whole body proteolysis, and a 29% decline in NOLD (180 +/- 15 v 223 +/- 13; P <.01), an index of whole body protein synthesis. In the protein-restricted group, dexamethasone treatment was associated with a 32% increase in Ra, (295 +/- 28 v 223 +/- 16; P <.05), a 186% increase in Ox (120 +/- 14 v 43 +/- 4; P <.001), with no change in NOLD, when compared with the protein-restricted alone. After protein restriction + dexamethasone, glutamine infusion induced a 40% increase in plasma glutamine (1,090 +/- 70 v 780 +/- 29 micromol x L(-1); P <.01), but failed to alter Ra, Ox, or NOLD. These results suggest that (1) in dogs, protein restriction combined with a 7-day course of dexamethasone results in alterations in leucine kinetics similar to those observed in stress-induced protein wasting in humans, and (2) in that model, a 7-hour IV glutamine infusion in the fasting state does not significantly attenuate protein wasting.     

Gene transfer to human joints: progress toward a gene therapy of arthritis

This article describes the clinical application of gene therapy to a nonlethal disease, rheumatoid arthritis (RA). Intraarticular transfer of IL-1 receptor antagonist (IL-1Ra) cDNA reduces disease in animal models of RA. Whether this procedure is safe and feasible in humans was addressed in a phase I clinical study involving nine postmenopausal women with advanced RA who required unilateral sialastic implant arthroplasty of the 2nd-5th metacarpophalangeal (MCP) joints. Cultures of autologous synovial fibroblasts were established and divided into two. One was transduced with a retrovirus carrying IL-1Ra cDNA; the other provided untransduced, control cells. In a dose escalation, double-blinded fashion, two MCP joints were injected with transduced cells, and two MCP joints received control cells. One week later, injected joints were resected and examined for evidence of successful gene transfer and expression by using RT-PCR, ex vivo production of IL-1Ra, in situ hybridization, and immunohistochemistry. All subjects tolerated the protocol well, without adverse events. Unlike control joints, those receiving transduced cells gave positive RT-PCR signals. Synovia that were recovered from the MCP joints of intermediate and high dose subjects produced elevated amounts of IL-1Ra (P = 0.01). Clusters of cells expressing high levels of IL-1Ra were present on synovia of transduced joints. No adverse events occurred. Thus, it is possible to transfer a potentially therapeutic gene safely to human rheumatoid joints and to obtain intraarticular, transgene expression. This conclusion justifies additional efficacy studies and encourages further development of genetic approaches to the treatment of arthritis and related disorders.     

Recombinant human interleukin-1 receptor antagonist in the treatment of steroid-resistant graft-versus-host disease

Acute graft-versus-host disease (GVHD) that is resistant to therapy is a highly lethal complication of marrow transplantation. Inflammatory cytokines such as interleukin-1 (IL-1) may be critical mediators of this process. If so, specific inhibition of IL-1 activity with recombinant human IL-1 receptor antagonist (IL-1Ra), a naturally occurring competitive inhibitor of IL-1, may ameliorate acute GVHD. We performed an open-label, phase I/II trial to evaluate the safety and efficacy of IL-1Ra in 17 patients with steroid-resistant GVHD. The IL- 1Ra was administered as a 24-hour continuous infusion over 7 days. The dose was escalated in cohorts of patients from 400 to 3,200 mg/d. Acute GVHD was evaluated in each affected organ and as an overall grade. Stage-specific improvement of acute GVHD occurred in the skin (8 of 14, 57%), gut (9 of 11, 82%), and liver (2 of 11, 18%). Overall, acute GVHD improved by at least one grade in 10 of 16 (63%) patients. Response to therapy was associated with a reduction of tumor necrosis factor-alpha (TNF-alpha) mRNA levels in blood mononuclear cells (P = .001). The only toxicity attributable to IL-1Ra was reversible transaminase elevation in two patients. Inhibition of IL-1 activity with IL-1Ra is safe and has demonstrable efficacy in acute GVHD that failed to respond to conventional treatment. These data provide further evidence that IL-1 is a mediator of GVHD.     

Effect of interleukin-1 and tumor necrosis factor/cachectin on glucose turnover in the rat

We studied the effect of recombinant human interleukin-1 beta (IL-1) and recombinant human tumor necrosis factor alpha/cachectin (TNF) on glucose kinetics in healthy rats by means of a primed constant infusion of D-(6-3H)glucose and D-[U-14C]glucose. During the isotope (6-hour) and monokine (4-hour) infusion, plasma levels of glucagon and insulin were determined and correlated with changes in glucose metabolism. The rates of glucose appearance (Ra) and disappearance (Rd) were elevated only with IL-1 and were associated with an increase in glucagon and a concomitant decrease in the ratio of insulin to glucagon. Plasma glucose concentration was increased early after IL-1 administration and coincided with the peak in the Ra. The augmentation of the metabolic clearance rate (MCR) and percent of flux oxidized by IL-1 suggest that this monokine induces the utilization of glucose as a substrate. TNF administration failed to modify the Ra or Rd, percent of flux oxidized, or MCR. TNF-treated rats increased the percent of glucose recycling, but not the total rate of glucose production. The results of this experiment suggest that endogenous macrophage products participate in the diverse alterations of carbohydrate metabolism seen during injury and/or infection.     

Fasting decreases free fatty acid turnover in mice overexpressing skeletal muscle lipoprotein lipase

Skeletal muscle lipoprotein lipase (LPL) overexpression in mice results in whole-body insulin resistance and increased intramuscular triglyceride stores, but decreased plasma triglyceride concentration and unchanged plasma free fatty acid (FFA) concentration. The effects of skeletal muscle LPL overexpression and fasting duration on FFA kinetics are unknown. Transgenic mice with muscle-specific LPL overexpression (MCKhLPL) and control mice (Con) were studied at rest during a 50-minute constant infusion of [9,10- 3H]palmitate to determine FFA kinetics after both 4 and 16 hours of fasting. FFA concentration was not different between groups after the 4-hour (Con, 0.80 +/- 0.06 mmol/L; MCKhLPL, 0.83 +/- 0.07 mmol/L) and 16-hour (Con, 0.83 +/- 0.04 mmol/L; MCKhLPL, 0.80 +/- 0.07 mmol/L) fast. FFA turnover (Ra) was not significantly different between MCKhLPL and Con groups after the 4-hour fast (Con Ra = 2.52 +/- 0.36 micromol/min; MCKhLPL Ra = 2.37 +/- 0.27 micromol/min). However, FFA turnover was significantly decreased after the 16-hour fast in MCKhLPL mice vs controls (Con Ra = 2.89 +/- 0.52 micromol/min; MCKhLPL Ra = 1.64 +/- 0.17 micromol/min; P < .05). The significantly lower FFA Ra in MCKhLPL vs control mice was due to a decrease in MCKhLPL FFA turnover from the 4- to 16-hour fast, whereas FFA turnover was unchanged in controls. The changes in FFA appearance after the 16-hour fast in MCKhLPL mice are most likely explained by increased reliance by skeletal muscle on plasma triglyceride as a fuel. These data suggest increased skeletal muscle LPL expression decreases dependence on plasma FFA during prolonged fasting in mice.     

beta-Adrenergic regulation of IL-6 release from adipose tissue: in vivo and in vitro studies.

Circulating IL-6 levels are elevated in obesity. Although IL-6 is expressed in adipose tissue, neither its regulation nor cell of origin is well characterized. Here we investigated the beta-adrenergic regulation of IL-6 release in a combination of studies on humans and animals in vivo and cultured adipocytes in vitro. Human in vivo study: Human volunteers were infused with isoproterenol, norepinephrine, or saline [4 M:4F; mean (SD) age 35.5 (5.8) yr; body mass index 24.6 (4.2) kg/m(-2)]. Plasma IL-6 levels increased during a 3-h infusion of isoproterenol (P = 0.01) and fell 2 h post infusion (P = 0.05). IL-6 levels did not change significantly with either norepinephrine or saline. Murine in vivo study: C57BL6/J male mice were injected ip with dobutamine (beta(1) agonist), clenbuterol (beta(2)), CL316243 (beta(3)), or saline placebo. Plasma IL-6 levels at 3 h were increased by clenbuterol (P = 0.02) and CL316243 (P = 0.02) but not dobutamine (P = 0.51), compared with placebo. In vitro studies: In human peripheral blood cells, lipopolysaccharide treatment enhanced secretion of IL-6 (vs. controls; P < 0.001), whereas isoproterenol inhibited IL-6 secretion (P = 0.012) and norepinephrine had no significant effect. In contrast, isolated human adipocytes and differentiated 3T3F442A adipocytes all rapidly secreted IL-6 in response to adrenergic agonists (P < 0.01, compared with untreated cells). We conclude that beta 2/beta 3 adrenoceptor stimulation on adipocytes, rather than macrophages, may be responsible for the increases in plasma IL-6 concentrations observed during sympathetic activation and in obesity.     

IL-1 receptor antagonist serum levels are increased in human obesity: a possible link to the resistance to leptin?

We have recently shown that human monocytic cells express functional leptin receptors and that leptin is capable of inducing the expression and secretion of the IL-1 receptor antagonist (IL-1Ra). Although IL-1Ra has anti-inflammatory and possibly anti-atherogenic properties, it has also been shown to antagonize the action of leptin at the hypothalamic level in rodents, thereby inducing leptin resistance. We have therefore examined whether IL-1Ra levels are increased in human hyperleptinemic conditions, such as obesity. To this end, we measured serum IL-1Ra levels in 20 morbidly obese nondiabetic subjects [body mass index (BMI), 45 +/- 6 kg/m(2); serum leptin, 52 +/- 20 ng/ml] as well as in 10 age- and sex-matched lean controls (BMI, 22 +/- 2 kg/m(2); serum leptin, 7 +/- 4 ng/ml). Serum IL-1Ra concentrations proved to be elevated 6.5-fold in the obese subjects, and they were positively correlated in a linear manner with the leptin levels (r(2) = 0.34; P = 0.01), although lean body mass (LBM) and the insulin resistance index were even better predictors of IL-1Ra levels (r(2) = 0.45 and 0.58, respectively; P < 0.01). Six months after 15 of the 20 obese subjects had undergone bypass surgery for their morbid obesity, their mean BMI and leptin levels decreased to 33 +/- 7 kg/m(2) and 18 plus minus 12 ng/ml, respectively. This change in leptin concentrations was associated with a significant reduction in IL-1Ra levels (P < 0.02). However, there was a better correlation between the decrease in IL-1Ra level and the change in LBM than with the reduction in leptin levels, indicating that leptin is not the sole determinant of circulating IL-1Ra in obesity. In summary, we demonstrate that IL-1Ra levels are highly elevated in human obesity and that its concentrations decrease after weight loss from bypass surgery. However, LBM and insulin resistance are better predictors of serum IL-1Ra concentrations than are leptin levels, suggesting that additional metabolic factors control the secretion of this cytokine antagonist. Although the immunological consequences of this alteration remain unknown, it is tempting to speculate that the obesity-related increase in IL-1Ra might contribute to the central resistance to leptin in obese patients, similar to the inhibition of the hypothalamic signaling of leptin by IL-1Ra in rodents.     

Iso-osmolar prehydration shifts the cytokine response towards a more anti-inflammatory balance in human endotoxemia

Clinical experience suggests that the administration of fluids in human endotoxemia reduces symptoms. In the present study, the effects of a standardised fluid protocol on symptoms, inflammatory and hemodynamic parameters in human endotoxemia are determined. With approval of the local ethics committee, 16 healthy volunteers received 2 ng/kg of Escherichia coli endotoxin (O:113). After an overnight fast, nine subjects received 1.5 l of 2.5% glucose/0.45% NaCl the hour prior to the endotoxin administration and 150 ml/h during the course of the experiment ('prehydrated group'). Seven subjects only received a continuous infusion of 75 ml/h during the experiment ('non-prehydrated group'). The course of inflammatory parameters and symptoms were determined and mean arterial pressure, heart rate and forearm blood flow were measured. In the prehydrated group, TNF-alpha increased to 522 +/- 63 pg/ml (mean +/- SEM) while the maximum in the non-prehydrated group was 927 +/- 187 pg/ml (P < 0.04). IL-10 increased similarly in both groups (non-prehydrated 117 +/- 18 pg/ml and prehydrated 99 +/- 18 pg/ml; P = NS). The prehydrated group had a significantly lower (P < 0.004) symptom score and recovered sooner (P = 0.004). Endotoxin-induced changes in hemodynamics revealed no significant differences between groups. We demonstrate that prehydration in experimental human endotoxemia significantly shifts the cytokine balance towards a more anti-inflammatory pattern. This effect is associated with a reduction in symptoms, whereas the changes in hemodynamic parameters are not influenced by prehydration.     

Dysregulation of the in vivo production of interleukin-1 receptor antagonist in patients with rheumatoid arthritis pathogenetic implications

Objective. Patients with rheumatoid arthritis (RA) have defective hypothalamic responses to inflammation, possibly because of excessive production of cytokine inhibitor, which could blunt the effects of cytokines on the hypothalamus, or because of an imbalance between interleukin-1β (IL-1β) and interleukin-1 receptor antagonist (IL-1Ra), which could create a mainly proinflammatory state. The present study was undertaken to investigate these possibilities. Methods. The in vivo kinetics of IL-1β and IL-1Ra secretion were studied in patients with RA, osteoarthritis (OA), and chronic osteomyelitis (OM), and in normal controls before and after surgery. Results. The 24-hour levels of IL-1Ra were significantly increased in RA (P < 0.001), but there was no diurnal variation in any group. Preoperative levels of IL-1Ra were higher in RA and OA sera (P = 0.001). After surgery, IL-1Ra behaved like an acute-phase reactant protein in all subjects. IL-1β was 10–20 times higher in RA than in OM and OA patients at baseline, but the percentage increase in all groups postoperatively was the same. RA patients had an IL-1Ra:IL-1β ratio of 26.2 ± 3.7 (mean ± SEM) at baseline (OM patients 89.2 ± 5.8 and OA patients 1,310 ± 363); this increased to 66.5 ± 19.8 after surgery (OM patients 120 ± 6.7 and OA patients 325.8 ± 106). Conclusion. RA patients have a dysregulation of IL-1Ra production, and it seems unlikely that the defective hypothalamic response seen in RA is due to a functional deficit of IL-1β.     

Effects of recombinant soluble type I interleukin-1 receptor on human inflammatory responses to endotoxin

Effects of soluble recombinant human type I interleukin-1 receptor (sIL- 1RI) were evaluated in 18 volunteers given intravenous endotoxin and randomized to placebo (n = 6), low-dose (n = 6), or high-dose (n = 6) sIL-1RI. Soluble IL-1RI decreased IL-1 beta (P = .001), but decreased IL-1ra (P = .0001), and resulted in 10-fold and 43-fold dose-related increases in sIL-1RI-IL-1ra complexes compared with placebo (P < or = .001). High-dose sIL-1RI was associated with increased levels of immunoactive tumor necrosis factor-alpha (P = .02), IL-8 (P = .0001), and cell-associated IL-1 beta (P = .047). C-reactive protein levels were higher after sIL-1RI than placebo (P = .035). Soluble IL-1RI decreased the severity of chills (P = .03), but did not alter other symptoms, changes in temperature, systemic hemodynamic responses, or changes in leukocyte and platelet number. Thus, sIL-1RI had no discernable antiinflammatory effect following endotoxin administration due in part to low levels of circulating IL-1 beta and neutralization of IL-1ra inhibitory function. This latter interaction represents an indirect mechanism of agonist activity elicited by sIL-1RI and may contribute to increases in inflammatory mediators, limiting therapy with sIL-1RI during endotoxemia.     

Activation of the kallikrein-kinin system after endotoxin administration to normal human volunteers

The objective of this study was to determine the role of the kallikrein- kinin system in healthy humans after intravenous administration of either Escherichia coli endotoxin or saline. We studied a total of 18 healthy nonsmoking volunteers, 23 to 38 years old, in an open-label study at the Critical Care Medicine Department, Clinical Center, National Institutes of Health (Bethesda, MD) in which some of the patients served as their own controls. After baseline data collection, the subjects received intravenously either E coli endotoxin (n = 15, 4 ng/kg of body weight) or saline (n = 8, controls). Signs, symptoms, systemic blood pressure, factor XII, plasma prekallikrein (PK), factor XI (FXI), antithrombin III (AT-III), high molecular weight kininogen (HK), and alpha 2-macroglobulin-kallikrein complexes were measured at baseline and 1, 2, 3, 5, and 24 hours after injection of either saline or endotoxin. After infusion of endotoxin, we found the functional plasma levels of FXI decreased at 2 hours (P < .05) and at 5 hours (P < .05). Functional PK was significantly depressed by 2 hours (P < .05), at 5 hours (P < .05), and at 24 hours (P < .01), whereas the PK antigen was only low at 5 hours (P < .05). These changes were accompanied by a significant increase in circulating alpha 2-macroglobulin-kallikrein complexes at 3 hours (P < .05) and 5 hours (P < .01). No significant changes occurred in the plasma levels of factor XII or HK. We concluded that clinical response to intravenous endotoxin in healthy human volunteers is associated with activation of the kallikrein-kinin systems. Further investigation is needed with specific inhibitors of the kallikrein-kinin system to define its primary or secondary role in the endotoxin-mediated reactions.     

The effects of treatment with interleukin-1 receptor antagonist on the inflamed synovial membrane in rheumatoid arthritis

OBJECTIVE: To evaluate the effects of treatment with interleukin-1 receptor antagonist (IL-1Ra) on synovial tissue in rheumatoid arthritis (RA). METHODS: Twelve patients with RA entering a randomized clinical trial of human recombinant IL-1Ra underwent synovial biopsies before and after treatment. Cellular infiltration and adhesion molecule expression were evaluated after immunohistochemical staining. RESULTS: There was a notable reduction in intimal layer macrophages and subintimal macrophages and lymphocytes after treatment with IL-1Ra at 150 mg/day (n=3). Increased cellular infiltration was observed in all patients receiving placebo (n=3); variable changes were observed after IL-1Ra 30 mg/day (n=6). In a limited study of adhesion molecule expression, down-regulation of E-selectin and vascular cell adhesion molecule-1 was observed after treatment with IL-1Ra 150 mg/day, but not after IL-1Ra 30 mg/day or placebo. The apparent arrest of progressive joint damage seen in four patients after treatment with IL-1Ra was associated with reduced intimal layer macrophage accumulation in all patients. CONCLUSION: Treatment of RA with IL-1Ra resulted in reduced mononuclear cell infiltration of synovial membrane, which may represent the in vivo inhibition of biologically relevant IL-1ss-mediated pathogenic effects.     

Low-dose steroid alters in vivo endotoxin-induced systemic inflammation but does not influence autonomic dysfunction

Severe injury and infection are associated with autonomic dysfunction. Diminished heart rate variability (HRV) is also observed as a component of autonomic dysfunction and is induced by endotoxin administration to healthy subjects. It is established that low-dose glucocorticoid administration diminishes the systemic inflammatory manifestations of endotoxinemia but the influence of this anti-inflammatory intervention on overall autonomic dysfunction and HRV responses to endotoxin is unknown. This study was designed to assess the influence of a low-dose hydrocortisone infusion upon endotoxin-elicited systemic inflammatory responses including phenotypic features, cytokine production, and parameters of HRV. Of 19 subjects studied, nine received a continuous infusion of hydrocortisone (3 microg/kg/min continuously over 6 h) prior to intravenous administration of Escherichia coli endotoxin (2 ng/kg, CC-RE, Lot #2) while 10 healthy subjects received only the endotoxin after a 6-h period of saline control infusion. Serial determinations of vital signs, heart rate variability assessments, and cytokine levels were obtained over the subsequent 24 h. Prior cortisol infusion diminished the peak TNF-alpha (P < 0.01) and IL-6 (P < 0.0001) responses after endotoxin challenge, as compared to saline infusion controls and diminished the peak core temperature response to endotoxin (P < 0.01). In contrast to the influence of cortisol on the above parameters of systemic inflammation, the significant endotoxin-induced decreases in HRV time and frequency domains were not influenced by prior hydrocortisone treatment. Hence, alterations in autonomic dysfunction occur despite hydrocortisone attenuation of other traditional systemic manifestations of endotoxinemia. The maintenance or restoration of autonomic balance is not influenced by glucocorticoid administration.     

Norepinephrine infusion during moderate-intensity exercise increases glucose production and uptake

A role for the increase in circulating norepinephrine (NE) during intense exercise [IE; > or = 80% maximum O(2) uptake (VO(2max))] in the marked increment in glucose rate of production (Ra) during IE is hypothesized. Seven fit male subjects (27 +/- 2 yr old; body mass index, 23 +/- 1 kg/m(2); VO(2max), 63 +/- 5 mL/kg.min) underwent 40 min of postabsorptive moderate-intensity (53% VO(2max)) cycle ergometer exercise (126 +/- 14 W), once without [control (CON)] and once with NE infusion (0.1 microg/kg.min) from 30-40 min (NE). With infusion, plasma NE reached 15.9 +/- 1.0 nM (8-fold rest, 2-fold CON). Ra doubled to 4.40 +/- 0.44 in CON, but rose to 7.55 +/- 0.68 mg/kg.min with NE infusion (P = 0.003). Ra correlated strongly (r(2) = 0.92, P < 0.02) with plasma NE during and immediately after infusion. With NE infusion, peak glucose uptake [rate of disappearance (Rd), 6.57 +/- 0.59 vs. 4.53 +/- 0.55 mg/kg.min, P < 0.02] and glucose metabolic clearance rate (P < 0.05) were higher than in CON. Glycemia rose minimally during the NE infusion but did not differ between groups at any time during exercise. Glucagon-to-insulin ratio increased minimally, and epinephrine increased approximately 2.5- to 3-fold at peak but did not differ between groups. Thus, NE infusion during moderate exercise led to increments in Ra and Rd in fit individuals, supporting a possible contributory role for the increase of plasma NE in IE. NE effects on Rd and metabolic clearance rate during exercise may differ from its effects at rest.     

Inflammatory markers and coronary interventions: a potentially useful follow-up modality after stenting.

Periprocedural levels of various inflammatory markers have been correlated with prognosis in patients undergoing percutaneous coronary interventions. However, long-term variations of interleukin-1 receptor antagonist (IL-1Ra) or C-reactive protein (CRP) during follow-up after coronary interventions were not previously investigated. The aim of our study was to perform serial evaluations of these markers before and after coronary stenting and to correlate them with clinical status. Plasma levels of IL-1Ra and CRP were measured at baseline and 3 and 6 months after the procedure in 31 patients with symptomatic coronary artery disease undergoing stent implantation, who had no evidence of myocardial ischemia at 6-month follow-up. While at 3 months there were no significant variations of baseline values, 6 months after the procedure a significant decrease from baseline was observed both in IL-1Ra and CRP levels (median -24 pg/ml, P = 0.048, and -0.13 mg/dl, P = 0.017, respectively). Six-month reduction in both IL-1Ra and CRP levels was significant in patients with unstable angina (n = 18; IL-1Ra: from 175 to 119 pg/ml, P = 0.001; CRP: from 0.52 to 0.18 mg/dl, P = 0.002) and nonsignificant in those with stable angina (n = 13) on admission (IL-1Ra: from 123 to 158 pg/ml, P = 0.22; CRP: from 0.19 to 0.10 mg/dl, P = 0.44). In conclusion, a significant reduction of IL-1Ra and CRP levels is observed 6 months after stent implantation in patients with preprocedural unstable angina who remain free of ischemia. This decrease suggests a stabilization of the inflammatory process and may be associated with a favorable prognosis after coronary interventions.     

Pretreatment with ibuprofen augments circulating tumor necrosis factor-alpha, interleukin-6, and elastase during acute endotoxinemia

Plasma levels of tumor necrosis factor-alpha (TNF alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6) were monitored after intravenous administration of Escherichia coli endotoxin with or without ibuprofen pretreatment to healthy volunteers. Intravenous endotoxin (n = 7) resulted in elevated plasma TNF alpha concentrations with maximal levels at 90 min (369 +/- 44 pg/ml, P less than .001 vs. saline controls, n = 7). The rise in TNF-alpha was followed by a rise in plasma IL-6 (27 +/- 12.8 ng/ml), peaking 30-90 min thereafter. Pretreatment with ibuprofen (n = 6) caused a significant augmentation and temporal shift in cytokine elaboration with maximal TNF alpha levels (627 +/- 136 pg/ml) at 120 min and IL-6 peaks (113 +/- 66 ng/ml) at 180 min. In ibuprofen-treated volunteers, the additional increase in TNF alpha was paralleled by increased levels of circulating elastase. In vitro experiments suggest a causal relationship between these events. Thus, the cyclooxygenase inhibitor ibuprofen blunts the clinical response to endotoxin but augments circulating cytokine levels and leukocyte degranulation.