Ageing Is Associated with a Prolonged Fever Response in Human Endotoxemia

The purpose of this study was to investigate whether an age-associated impaired acute-phase response exists. Nine healthy elderly volunteers (median, 66 years; range, 61 to 69 years) and eight young controls (median, 24 years; range, 20 to 27 years) were given an intravenous bolus of endotoxin (2 ng/kg). The rectal temperature was monitored continuously, and blood samples for cytokine measurements were obtained before endotoxin administration as well as 0.5, 1, 1.5, 2, 3, 4, 8, 12, and 24 h after the injection. The elderly subjects showed a more prolonged fever response compared to the young controls. Levels of tumor necrosis factor alpha (TNF-α), soluble TNF receptors (sTNFR-I), interleukin-6 (IL-6), IL-8, IL-10, and IL-1 receptor antagonist (IL-1ra) in plasma increased markedly following endotoxin administration in both groups. The elderly group showed larger initial increases in TNF-α and sTNFR-I levels and prolonged increased levels of sTNFR-I. Monocyte concentrations decreased in both groups, with the elderly group showing a more rapid decrease and a slower subsequent increase than did the young group. Furthermore, the elderly group had a more rapid increase in C-reactive protein levels than did the young group. In conclusion, ageing is associated with an altered acute-phase response including initial hyperreactivity, prolonged inflammatory activity, and prolonged fever response.     

Impaired production of proinflammatory cytokines in response to lipopolysaccharide (LPS) stimulation in elderly humans.

Ageing is associated with decreased resistance to bacterial infections and concomitant increased circulating levels of inflammatory cytokines. The purpose of the present study was to research age-related changes in levels of early mediators of the acute-phase response in whole blood supernatants following LPS stimulation, representing an ex vivo model of sepsis. Levels of tumour necrosis factor-alpha (TNF-alpha), IL-1beta and IL-6 in whole blood supernatants were measured after in vitro LPS stimulation for 24 h in 168 elderly humans aged 81 years from the 1914 cohort in Glostrup, Denmark and in 91 young controls aged 19-31 years. Levels of TNF-alpha and IL-1beta were significantly lower in elderly humans compared with young controls, whereas no difference was detected with regard to IL-6. Elderly humans with low body mass index had the lowest levels of IL-1beta. Young women had lower levels of proinflammatory cytokines compared with young men, but this difference was blurred by ageing. No relation was found between circulating plasma levels of TNF-alpha and levels after in vitro LPS stimulation. In conclusion, decreased production of TNF-alpha and IL-1beta after exposure to LPS may reflect impaired host defence against infections in the elderly and be of importance in elderly humans with underlying health disorders. However, the clinical relevance is questionable in healthy elderly people because decreased levels were found compared with young men but not compared with young women.     

Fever after zoledronic acid administration is due to increase in TNF-alpha and IL-6.

The most common adverse event typically associated with bisphosphonate therapy is transient fever. The aim of this study was to define the role of the main cytokines of the acute-phase reaction interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) involved in the pathogenesis of zoledronic acid-induced fever. Eighteen consecutive cancer patients with bone metastases were treated, for the first time, with a single dose of 4 mg zoledronic acid infusion. They were prospectively evaluated for circulating TNF-alpha, interferon-gamma (IFN-gamma), and IL-6 levels at different times, just before and 1, 2, 7, and 21 days after diphosphonate infusion. Clinical and standard laboratory parameters were recorded at the same time points. TNF-alpha circulating levels increased significantly 1 and 2 days after zoledronic acid infusion (respectively, p = 0.002 and p < 0.001) and then decreased to levels similar to the basal levels. IL-6 levels increased significantly 1 day after the infusion (p = 0.007), returning to values similar to the median basal values 2 days after zoledronic acid administration. Moreover, in patients who experienced fever, the TNF-alpha and IL-6 increases were higher than in patients without fever. No statistically significant differences in IFN-gamma were identified at different time points in patients with and without fever. Our results show that zoledronic acid induces transient TNF-alpha and IL-6 increases and that these increases are higher in patients who have developed fever, suggesting that these cytokines could be responsible for fever pathogenesis. The sharp reduction in serum calcium levels observed in patients with fever may be related to zoledronic acid pharmacokinetic modifications.     

Circulating levels of TNF-alpha and IL-6-relation to truncal fat mass and muscle mass in healthy elderly individuals and in patients with type-2 diabetes

The purpose of the current study was to test the hypothesis that an altered fat distribution in elderly healthy subjects and in patients with type-2 diabetes contributes to high circulating levels of interleukin (IL)-6 and tumor necrotic factor (TNF)-alpha, which secondly is related to lower muscle mass. Twenty young controls, (20-35 yr), 20 healthy elderly subjects (65-80 yr) and 16 elderly patients with type 2 diabetes (65-80 yr) were included in a cross sectional study. Plasma levels of TNF-alpha and IL-6 were measured after an overnight fast. Dual-energy X-ray absorptiometry and total body potassium counting measured truncal fat, appendicular skeletal muscle mass (ASM) and body cell mass (BCM), respectively. TNF-alpha, IL-6 and the relative truncal fat mass were higher in elderly compared with young controls. ASM was lower in diabetic men than in young controls and BCM was lower in elderly men compared with young men. TNF-alpha and IL-6 were correlated with the absolute as well as the relative truncal fat mass in univariate regression analyses. Similar results were found in multivariate linear regression analyses after adjusting for the effect of age and gender. TNF-alpha was related to lower ASM and BCM in elderly men both in a univariate regression analysis and a multivariate regression analysis. In conclusion, high plasma levels of TNF-alpha and IL-6 in elderly healthy people and in patients with type 2 diabetes are associated with increased truncal fat mass, suggesting that cytokines are partly derived from this adipose tissue bed. Furthermore, TNF-alpha was related to lower ASM and BCM, suggesting that TNF-alpha contributes to sarcopenia in ageing.     

Symptom pathogenesis during acute influenza: interleukin-6 and other cytokine responses.

In experimental human influenza infection initiated by nasal inoculation, the magnitude of viral replication, fever, and symptoms correlate with nasopharyngeal lavage fluid levels of various cytokines. Our aim was to assess these relationships in patients with naturally occurring acute influenza. Patients with culture-positive influenza illness of less than 36 hr of duration were studied. Nasopharyngeal washing were collected at enrollment and on Day 2, 4, 6 and 8 for quantitative virus isolation and IL-6, TNF-alpha, INF-alpha, INF-gamma and IL-10 determinations. Blood samples collected at entry and on Day 2 and 6 were processed to assess plasma cytokines and circulating influenza RNA. Patients received either oseltamivir or placebo for 5 days. We assessed the correlation between nasopharyngeal lavage fluid or blood levels of cytokines before treatment and viral titers, symptom severity and fever. Sixteen adult subjects (median age of 22 years) were studied. In this small group of patients no significant differences between placebo and oseltamivir patients were found in viral replication or measures of cytokines. Thus the data for all 16 subjects were pooled for analysis. At entry, influenza A viruses were cultured from nasopharyngeal washes at a median titer of 4.8 log(10)TCID(50)/ml of wash. Viral titers correlated positively with symptom score (P = 0.006) and temperature values (P < 0.001). Viral titers, fever and symptoms were highest at enrollment and fell in parallel during the subsequent days. RT-PCR assays failed to detect influenza RNA in the white blood cells from any patient. We observed a significant release, in both nasopharyngeal lavage fluid and in plasma, of IL-6, TNF-alpha, INF-alpha, INF-gamma and IL-10. At entry high IL-6 levels were detected in the nasopharyngeal lavage fluid (median 10.3 pg/ml) and plasma (median 5.1 pg/ml) of all patients. We found a positive correlation between plasma IL-6 levels and both symptom scores and temperature values (P < 0.05), as well as a positive correlation between nasopharyngeal lavage fluid levels of IL-6 and TNF-alpha and temperature (P < 0.05). We did not find significant associations between symptoms, fever and levels of INF-alpha, INF-gamma or IL-10. The magnitude of early decrease in viral titers correlated with initial levels of INF-gamma in nasopharyngeal lavage fluid (P < 0.05). Significant production of IL-6, TNF-alpha, INF-alpha, INF-gamma and IL-10 occurs in response to community acquired influenza A illness. As in experimental influenza, symptoms and fever in natural acute influenza correlate with the release of IL-6.     

Regulatory effects of fever-range whole-body hyperthermia on the LPS-induced acute inflammatory response

The thermal component of fever is one of the most poorly understood aspects of inflammation. To evaluate the role of fever-range hyperthermia on acute inflammation, BALB/c and C57BL/6 mice were exposed to mild, long-duration whole-body hyperthermia (WBH), and serum concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), IL-1beta, and the acute phase proteins (APPs) alpha1-acid glycoprotein and haptoglobin were analyzed. WBH alone did not affect serum concentrations of these cytokines or APPs when compared with controls. In contrast, when WBH was applied just after intraperitoneal administration of lipopolysaccharide (LPS), serum concentrations of TNF-alpha and IL-6 were greater than or equal to threefold higher in BALB/c mice compared with LPS-treated controls. LPS-induced IL-6 levels were also enhanced in WBH-treated C57BL/6 mice. However, APP levels were prolonged only in WBH-treated BALB/c mice. It is interesting that in vitro hyperthermia treatment of LPS-stimulated peritoneal cells resulted in decreased cytokine production compared with controls. These results suggest that fever-range hyperthermia regulates acute inflammation in a mouse strain-specific manner that is more complex than that observed in vitro.     

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.     

High interleukin-10 production is associated with low antibody response to influenza vaccination in the elderly

The present study was designed to determine the correlation among dehydroepiandrosterone (DHEA), cortisol plasma levels, and immune functionality at the time of vaccination with antibody response to influenza vaccination in young and old, healthy volunteers. Fifty-two elderly subjects, ages 63-85 years, and 14 young subjects, ages 26-41 years, entered the study. Plasma levels of DHEA and cortisol and in vitro cytokine production in response to lipopolysaccharide (LPS) and phytohaemagglutinin (PHA) by peripheral blood leukocytes were assessed at the time of vaccination, and antibody titer was measured before and 18 days after influenza virus vaccination. Elderly subjects were characterized by an increase in the cortisol:DHEA ratio, mainly as a result of a decrease in DHEA. A decrease in LPS-induced tumor necrosis factor alpha (TNF-alpha), increased PHA-induced interleukin-10 (IL-10) release, and similar PHA-induced interferon-gamma production were observed in elderly subjects compared with young volunteers. Lower antibody titer to influenza A virus was observed in elderly individuals, and the seroconversion factor was found to be correlated inversely with IL-10 production and correlated directly with TNF-alpha production and to a lesser extent, with the plasma level of DHEA. These results suggest that altered cytokine production in elderly subjects at the moment of vaccination can be predictive of a low response to influenza vaccination and warrant the study of strategies to improve protection afforded by the use of vaccines.     

The effect of age on the systemic inflammatory response in patients with community-acquired pneumonia

Community-acquired pneumonia (CAP) is a major cause of morbidity and mortality worldwide. Increasing age has been associated with elevated circulating levels of pro-inflammatory mediators. We aimed to determine the impact of ageing on the systemic inflammatory response to CAP. In total 201 CAP patients were enrolled. Blood samples were obtained upon presentation, and on days 2, 3 and 5. For the current analysis patients ≤50 and ≥80 years were included. The Pneumonia Severity Index (PSI) score was calculated at presentation. The study encompassed 46 CAP patients aged ≤50 years (median 37 years) and 41 CAP patients aged ≥80 years (median 84 years). In both groups Streptococcus pneumoniae was the common causative microorganism. Whereas most young patients had a PSI score of I (54%), 98% of elderly patients had a PSI score ≥III (p <0.001). Four elderly patients died vs. none of the young patients (p 0.045). Older patients demonstrated lower serum C-reactive protein levels on admission and during the course of their hospitalization (p 0.001) in spite of more severe disease. Serum concentrations of pro-inflammatory (interleukin (IL)-6 and IL-8) and anti-inflammatory cytokines (IL-10 and IL-1 receptor antagonist) did not differ between age groups, although admission IL-8 levels tended to be higher in elderly patients (p 0.05). Cytokine levels were positively correlated with PSI in young but not in elderly patients. These results suggest that elderly patients show an absolute (C-reactive protein) or relative (cytokines) reduction in their systemic inflammatory response on admission for CAP.     

Cytokines as mediators for or effectors against rotavirus disease in children

Rotavirus is the most common cause of severe gastroenteritis in young children, but the pathogenesis and immunity of this disease are not completely understood. To examine the host response to acute infection, we collected paired serum specimens from 30 children with rotavirus diarrhea and measured the levels of nine cytokines (interleukin-1beta [IL-1beta], IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, gamma interferon [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]) using a microsphere-based Luminex Flowmetrix system. Patients with acute rotavirus infection had elevated median levels of seven cytokines in serum, and of these, the levels of three (IL-6, IL-10, and IFN-gamma) were significantly (P < 0.05) higher than those in serum from control children without diarrhea. Patients with fever had significantly (P < 0.05) higher levels of IL-6 in serum than control children, and those with fever and more episodes of diarrhea had significantly (P < 0.05) higher levels of TNF-alpha than those without fever and with fewer episodes of diarrhea. We further demonstrated a negative association (P < 0.05) between the levels of IL-2 and the number of stools on the day on which the first blood sample was collected. Finally, patients with vomiting had significantly (P < 0.05) lower levels of IFN-gamma than those without vomiting. Our pilot study provides evidence that the types and magnitudes of cytokine responses to rotavirus infection in children influence or reflect the clinical outcome of disease. These findings suggest that certain cytokines may play an important role in the pathogenesis of and the protection against rotavirus disease in children and, consequently, may provide directions and insights that could prove critical to the prevention or treatment of this important disease.     

Tumor necrosis factor-alpha and interleukin-1 alpha synergistically enhance phorbol myristate acetate-induced superoxide production by rat bone marrow-derived macrophages.

Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 alpha (IL-1 alpha) are secreted by macrophages in response to endotoxin challenge. In addition, macrophages express receptors for both of these cytokines. Macrophage function can therefore be modulated by regulation of both cytokine production and receptor levels. We have initiated studies to investigate the effects of TNF-alpha and IL-1 alpha on macrophage function. Macrophages were obtained by in vitro differentiation of rat bone marrow cells. The biologic response to TNF-alpha and IL-1 alpha was assessed by measurement of superoxide production quantitated by the reduction of cytochrome c in response to phorbol myristate acetate. Macrophages were treated with endotoxin (LPS), TNF-alpha, and IL-1 alpha, alone and in combination. None of these agents was a primary stimulus for superoxide production. However, after treatment with endotoxin or TNF-alpha for 24 h, macrophages were primed for enhanced production of superoxide. The priming effect of LPS was due, at least in part, to endogenously produced TNF-alpha, since anti-murine TNF-alpha antibodies blocked the LPS-mediated priming by approximately 30%. IL-1 alpha did not prime macrophages, but treatment with IL-1 alpha followed by TNF-alpha or LPS resulted in enhanced superoxide production. IL-1 alpha treatment of macrophages resulted in an increase in TNF-alpha receptors, which might explain the synergistic priming of TNF-alpha and IL-1 alpha.     

Cholinergic status modulations in human volunteers under acute inflammation

Cholinergic Status, the total soluble circulation capacity for acetylcholine hydrolysis, was tested for putative involvement in individual variabilities of the recruitment of immune cells in response to endotoxin challenge. Young (average age 26) and elderly (average age 70) volunteers injected with either Escherichia coli endotoxin or saline on two different occasions were first designated Enhancers and Suppressors if they showed increase or decrease, respectively, in plasma acetylcholinesterase (AChE) activity 1.5 h after endotoxin administration compared to saline. Enhancers showed significant co-increases in plasma butyrylcholinesterase (BChE) and paraoxonase (PON1) activities, accompanied by rapid recovery of lymphocyte counts. Young Enhancers alone showed pronounced post-exposure increases in the pro-inflammatory cytokine interleukin-6 (IL-6), and upregulation of the normally rare, stress-induced AChE-R variant, suggesting age-associated exhaustion of the cholinergic effects on recruiting innate immune reactions to endotoxin challenge. Importantly, IL-6 injected to young volunteers or administered in vitro to primary mononuclear blood cells caused upregulation of AChE, but not BChE or PON1, excluding it from being the sole cause for this extended response. Interestingly, Suppressors but not Enhancers showed improved post-exposure working memory performance, indicating that limited cholinergic reactions may be beneficial for cognition. Our findings establish Cholinergic Status modulations as early facilitators and predictors of individual variabilities in the peripheral response to infection.     

Dose-dependence of bacterial lipopolysaccharide (LPS) effects on peak response and time course of the immune-endocrine host response in humans

OBJECTIVE AND DESIGN: Dose-dependence of lipopolysaccharide (LPS) effects on peak and time course parameters of the immune-endocrine host response was examined in a placebo-controlled design. SUBJECTS: Data from 42 male volunteers were included. TREATMENT: 0.4 or 0.8 ng LPS/kg body weight were applied at 7.00 p.m. METHODS: Body temperature, heart rate and leukocyte counts were quantified. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), adrenocorticotropic hormone (ACTH), cortisol and human growth hormone (hGH) were measured. RESULTS: LPS increased significantly the levels of immune (TNF-alpha, IL-6) and endocrine (ACTH, cortisol) parameters. HGH secretion was advanced without changes in the total amount of hGH released. Dose-dependence of endotoxin's effects was significant for neuroendocrine (cortisol) and physiological (temperature, heart rate) parameters. Examination of time course parameters demonstrated that the higher dose of endotoxin prolonged the increases in temperature, IL-6 and cortisol levels. CONCLUSIONS: Our data show that increases in the dosage of LPS lead to differential peak responses and changed time course patterns of the human host response.     

Effect of pentoxifylline on diaphragmatic contractility in septic rats

We investigated the effects of pentoxifylline (PTX) on endotoxin-induced diaphragmatic dysfunction in vitro. Seventy-two rats were divided into 3 groups: a group in which endotoxin (20 mg/kg) was injected intraperitoneally (endotoxin-group), a group in which PTX (100 mg/kg) was injected intraperitoneally 30 min before injection of endotoxin (endotoxin-PTX group), and a group in which only saline was given (sham group). Left hemidiaphragms were removed 4 h after injection of endotoxin. We evaluated the diaphragmatic contractility by twitch characteristics and force-frequency curves in vitro. We measured serum TNF-alpha concentrations, diaphragm malondialdehyde (MDA) levels (an index of oxygen-derived free radical-mediated lipid peroxidation), and diaphragm cAMP concentrations. Diaphragmatic force generation capacity was signifi cantly reduced after injection of endotoxin. Serum TNF-alpha concentrations and diaphragmatic MDA levels were significantly elevated after injection of endotoxin. PTX administration significantly improved diaphragmatic contractility and prevented the elevation in TNF-alpha concentrations and MDA levels after injection of endotoxin. There were no significant changes in the diaphragm cAMP concentrations among the 3 groups. These results demonstrated that PTX administration prevented endotoxin-induced diaphragmatic dysfunction without changing diaphragm muscle cAMP concentrations. The protective effects of PTX against endotoxininduced diaphragmatic contractile deterioration might be caused by attenuating TNF-alpha-mediated oxygen-derived free radical production.     

Variations in serum levels of interleukin (IL)-1beta, IL-2, IL-6, and tumor necrosis factor-alpha during specific immunotherapy.

BACKGROUND: Cytokine production by T helper cells is essential for the induction and maintenance of allergic inflammation in the bronchial mucosa. According to recent views, specific immunotherapy (SIT) favors the differentiation of T lymphocytes into cells of the Th1 rather than those of the Th2 subset. OBJECTIVE: To determine whether or not SIT induces a decrease in the inflammatory reaction by studying eventual variations in the serum levels of IL-1beta, IL-2, IL-6, and TNF-alpha in allergic subjects during SIT. METHODS: Serum levels of IL-1beta, IL-2, IL-6, and TNF-alpha were determined before and after 3, 6, and 9 months of SIT by an immunoradiometric assay (IRMA) in 11 adults with perennial allergic asthma and/or rhinitis caused by house dust mites and in 6 nonatopic healthy volunteers. RESULTS: Median serum IL-1beta and TNF-alpha levels of the patients were significantly higher at baseline than those of the controls and decreased during SIT to values similar to or lower (P < .01) after 6 months of SIT for TNF-alpha than those of the controls. Median serum IL-2, significantly lower at baseline than in the controls, increased during SIT to a level similar to that of the controls. Although the median values of IL-1beta and TNF-alpha in the patients tended to decrease and those of IL-2 to increase during SIT, the differences were not significant; the correlation coefficients (r) of the serum levels of IL-1beta IL-6, and TNF-alpha versus duration of SIT were negative, while that of IL-2 was positive. CONCLUSIONS: Decreases in median serum IL-1beta and TNF-alpha levels during SIT, together with the increases in serum IL-2 and IL-6, compared with those of the controls furnish evidence supporting a reduction in the inflammatory response in the course of SIT.     

Effect of low-dose cyclosporin a microemulsion on disease severity, interleukin-6, interleukin-8 and tumor necrosis factor alpha production in severe pediatric atopic dermatitis

BACKGROUND: The release of cytokines [interleukin-6 (IL-6), IL-8 and tumor necrosis factor-alpha (TNF-alpha)] by skin cells is involved in the pathogenesis of atopic dermatitis (AD). Objective: To evaluate the effect of low-dose cyclosporin A (CyA) on clinical symptoms and cytokine secretion in severe pediatric AD. METHODS: Ten children with severe AD (SCORAD index >50) were treated for 8 weeks with CyA. The initial dose of 2.5 mg/kg/day was titrated to a maximum of 5 mg/kg/day until a SCORAD reduction of >or =35% was achieved ("treatment response"). After stopping CyA all patients entered a 4-week follow-up period. Cytokine secretion (IL-6, IL-8 and TNF-alpha) from patients' PBMC was assessed by ELISA before and after CyA treatment and was compared with 18 healthy nonatopic controls. Only the data of patients, who responded to CyA and did not experience a relapse during the follow-up period, were evaluated for this paper. RESULTS: Seven patients responded to CyA without relapse during the follow-up period. The median SCORAD index in these patients improved from 71 at baseline to 22 after CyA treatment (p < 0.001). AD patients' PBMC produced more IL-6, IL-8 and TNF-alpha than PBMC of controls. Suppression of IL-6 (p < 0.05) and IL-8 (p < 0.05) production was observed after CyA treatment. TNF-alpha levels were unchanged by CyA in all patients. CONCLUSIONS: The reduction in severity of pediatric AD with CyA is associated with decreased production of IL-6 and IL-8, but not TNF-alpha by PBMC.     

Preexposure of murine macrophages to CpG oligonucleotide results in a biphasic tumor necrosis factor alpha response to subsequent lipopolysaccharide challenge

Bacterial DNA and synthetic oligonucleotides containing CpG sequences (CpG-DNA and CpG-ODN) provoke a proinflammatory cytokine response (tumor necrosis factor alpha [TNF-alpha], interleukin-12 [IL-12], and IL-6) and increased mortality in lipopolysaccharide (LPS)-challenged mice via a TNF-alpha-mediated mechanism. It was hypothesized that preexposure of macrophages to CpG-ODN would result in an increased TNF-alpha response to subsequent LPS challenge in vitro. Using the murine macrophage cell line RAW 264.7, we demonstrated both a rapid proinflammatory cytokine response (TNF-alpha) and a delayed inhibitory cytokine response (IL-10) with CpG-ODN. Preexposure of macrophages to CpG-ODN for brief periods (1 to 3 h) augmented TNF-alpha secretion and mRNA accumulation following subsequent LPS challenge (1 microg/ml). However, prolonged preexposure to CpG-ODN (6 to 9 h) resulted in suppression of the TNF-alpha protein and mRNA response to LPS. The addition of anti-IL-10 antibody to CpG-ODN during preexposure resulted in an increase in the LPS-induced TNF-alpha response over that induced by CpG-ODN preexposure alone. Thus, while brief preexposure of macrophages to CpG-ODN augments the proinflammatory cytokine response to subsequent LPS challenge, prolonged preexposure elicits IL-10 production, which inhibits the TNF-alpha response. Although the initial proinflammatory effects of CpG-DNA are well established, the immune response to CpG-DNA may also include autocrine or paracrine feedback mechanisms, leading to a complex interaction of proinflammatory and inhibitory cytokines.     

Infant home endotoxin is associated with reduced allergen-stimulated lymphocyte proliferation and IL-13 production in childhood

BACKGROUND: Infant endotoxin exposure has been proposed as a factor that might protect against allergy and the early childhood immune responses that increase the risk of IgE production to allergens. OBJECTIVE: Using a prospective study design, we tested the hypothesis that early-life endotoxin exposure is associated with allergen- and mitogen-induced cytokine production and proliferative responses of PBMCs isolated from infants with a parental history of physician-diagnosed asthma or allergy. METHODS: We assessed household dust endotoxin at age 2 to 3 months and PBMC proliferative and cytokine responses to cockroach allergen (Bla g 2), dust mite allergen (Der f 1), cat allergen (Fel d 1), and the nonspecific mitogen PHA at age 2 to 3 years. RESULTS: We found that increased endotoxin levels were associated with decreased IL-13 levels in response to cockroach, dust mite, and cat allergens, but not mitogen stimulation. Endotoxin levels were not correlated with allergen- or mitogen-induced IFN-gamma, TNF-alpha, or IL-10. Increased endotoxin levels were associated with decreased lymphocyte proliferation after cockroach allergen stimulation. An inverse, although nonsignificant, association was also found between endotoxin and proliferation to the other tested stimuli. CONCLUSION: Increased early-life exposure to household endotoxin was associated with reduced allergen-induced production of the TH2 cytokine IL-13 and reduced lymphoproliferative responses at age 2 to 3 years in children at risk for allergy and asthma. Early-life endotoxin-related reduction of IL-13 production might represent one pathway through which increased endotoxin decreases the risk of allergic disease and allergy in later childhood.     

Induction of interleukin-4 (IL-4) by legionella pneumophila infection in BALB/c mice and regulation of tumor necrosis factor alpha, IL-6, and IL-1beta

Infection of BALB/c mice with a sublethal concentration of Legionella pneumophila causes an acute disease that is resolved by innate immune responses. The infection also initiates the development of adaptive Th1 responses that protect the mice from challenge infections. To study the early responses, cytokines induced during the first 24 h after infection were examined. In the serum, interleukin-12 (IL-12) was detectable by 3 h and peaked at 10 h, while gamma interferon was discernible by 5 h and peaked at 8 h. Similar patterns were observed in ex vivo cultures of splenocytes. A transient IL-4 response was also detected by 3 h postinfection in ex vivo cultures. BALB/c IL-4-deficient mice were more susceptible to L. pneumophila infection than were wild-type mice. The infection induced higher serum levels of acute-phase cytokines (tumor necrosis factor alpha [TNF-alpha], IL-1beta, and IL-6), and reducing TNF-alpha levels with antibodies protected the mice from death. Moreover, the addition of IL-4 to L. pneumophila-infected macrophage cultures suppressed the production of these cytokines. Thus, the lack of IL-4 in the deficient mice resulted in unchecked TNF-alpha production, which appeared to cause the mortality. Monocyte chemoattractant protein-1 (MCP-1), a chemokine that is induced by IL-4 during Listeria monocytogenes infection, was detected at between 2 and 30 h after infection. However, MCP-1 did not appear to be induced by IL-4 or to be required for the TNF-alpha regulation by IL-4. The data suggest that the early increase in IL-4 serves to regulate the mobilization of acute phase cytokines and thus controls the potential harmful effects of these cytokines.     

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).