Circulating cytokine concentrations and cytokine production by monocytes from newborn babies and adults

Developmental psychoneuroendocrine and psychoneuroimmune pathways from childhood adversity to disease

Childhood adversity has been repeatedly and robustly linked to physical and mental illness across the lifespan. Yet, the biological pathways through which this occurs remain unclear. Functioning of the inflammatory arm of the immune system and the hypothalamic-pituitary-adrenal (HPA)-axis are both hypothesized pathways through which childhood adversity leads to disease. This review provides a novel developmental framework for examining the role of adversity type and timing in inflammatory and HPA-axis functioning. In particular, we identify elements of childhood adversity that are salient to the developing organism: physical threat, disrupted caregiving, and unpredictable environmental conditions. We propose that existing, well-characterized animal models may be useful in differentiating the effects of these adversity elements and review both the animal and human literature that supports these ideas. To support these hypotheses, we also provide a detailed description of the development and structure of both the HPA-axis and the inflammatory arm of the immune system, as well as recent methodological advances in their measurement. Recommendations for future basic, developmental, translational, and clinical research are discussed.

Fever and sickness behavior: Friend or foe?

Fever has been recognized as an important symptom of disease since ancient times. For many years, fever was treated as a putative life-threatening phenomenon. More recently, it has been recognized as an important part of the body's defense mechanisms; indeed at times it has even been used as a therapeutic agent. The knowledge of the functional role of the central nervous system in the genesis of fever has greatly improved over the last decade. It is clear that the febrile process, which develops in the sick individual, is just one of many brain-controlled sickness symptoms. Not only will the sick individual appear "feverish" but they may also display a range of behavioral changes, such as anorexia, fatigue, loss of interest in usual daily activities, social withdrawal, listlessness or malaise, hyperalgesia, sleep disturbances and cognitive dysfunction, collectively termed "sickness behavior". In this review we consider the issue of whether fever and sickness behaviors are friend or foe during: a critical illness, the common cold or influenza, in pregnancy and in the newborn. Deciding whether these sickness responses are beneficial or harmful will very much shape our approach to the use of antipyretics during illness.

Differential induction of cytokines by human neonatal, adult, and elderly monocyte/macrophages infected with dengue virus

Immunosuppressive status against infections in monocytes from neonates and elderly subjects has been reported. The interaction between dengue virus and monocytes/macrophages plays an important role during dengue disease. The aim of this study was to determine the cytokine response of monocytes from individuals with different ages after infection with dengue virus. Monocyte/macrophage cultures from neonatal, adult, and elderly subjects (n=10 each group) were incubated with all four dengue virus types (DENV-1 to -4). After 1 and 3 days of culture, cytokine concentrations (TNF-α, IL-6, and IL-1β) were determined in culture supernatants by enzyme-linked immunosorbant assay. Increased production of all studied cytokines was induced by the different viral types in monocyte/macrophage cultures regardless of their source. However, lower cytokine concentrations were found in neonatal and elderly monocytes. The relative monocyte/macrophage immunosuppressive status observed in neonates and the elderly could be relevant during dengue infection in those age groups and important in innate and adaptive immunity responses against this virus.

Differential oxidative stress induced by dengue virus in monocytes from human neonates, adult and elderly individuals

Changes in immune response during lifespan of man are well known. These changes involve decreased neonatal and elderly immune response. In addition, it has been shown a relationship between immune and oxidative mechanisms, suggesting that altered immune response could be associated to altered oxidative response. Increased expression of nitric oxide (NO) has been documented in dengue and in monocyte cultures infected with different types of dengue virus. However, there is no information about the age-dependent NO oxidative response in humans infected by dengue virus. In this study, monocyte cultures from neonatal, elderly and adult individuals (n = 10 each group) were infected with different dengue virus types (DENV- 1 to 4) and oxidative/antioxidative responses and apoptosis were measured at days 1 and 3 of culture. Increased production of NO, lipid peroxidation and enzymatic and nonenzymatic anti-oxidative responses in dengue infected monocyte cultures were observed. However, neonatal and elderly monocytes had lower values of studied parameters when compared to those in adult-derived cultures. Apoptosis was present in infected monocytes with higher values at day 3 of culture. This reduced oxidant/antioxidant response of neonatal and elderly monocytes could be relevant in the pathogenesis of dengue disease.

Staphylococcus epidermidis biofilms induce lower complement activation in neonates as compared with adults

BACKGROUND

Staphylococcus epidermidis (SE) is an important cause of late-onset sepsis in neonates. SE frequently produces a polysaccharide intercellular adhesin (PIA) biofilm, important in the pathogenesis of these infections. Little is known about how the neonatal innate immune system reacts to SE biofilm-associated infections. Our hypothesis was that SE biofilms induce a lower complement activation in neonates as compared with adults.

METHODS

Cord blood from term infants (n = 15) and blood from adults (n = 6) were studied in an ex vivo whole-blood sepsis model. A PIA biofilm-producing strain (SE1457) and its isogenic mutant (M10), producing a non-PIA biofilm, were used.

RESULTS

Both SE biofilms induced stronger complement activation in adult than in cord blood (P ≤ 0.033). We found lower levels of antibodies toward both PIA (P = 0.002) and the whole bacterium (P = 0.001) in cord vs. adult blood. By contrast, the interleukin-8 (IL-8) and IL-6 secretion were higher in cord than in adult blood (P ≤ 0.002). The PIA biofilm induced stronger complement activation than the non-PIA biofilm.

CONCLUSION

We conclude that the neonatal complement system exhibits a maturational deficiency. This may reduce the ability of neonates to combat biofilm-associated SE infections.

IL-10 administration reduces PGE-2 levels and promotes CR3-mediated clearance of Escherichia coli K1 by phagocytes in meningitis

Ineffectiveness of antibiotics in treating neonatal Escherichia coli K1 meningitis and the emergence of antibiotic-resistant strains evidently warrants new prevention strategies. We observed that administration of interleukin (IL)-10 during high-grade bacteremia clears antibiotic-sensitive and -resistant E. coli from blood of infected mice. Micro-CT studies of brains from infected animals displayed gross morphological changes similar to those observed in infected human neonates. In mice, IL-10, but not antibiotic or anti-TNF antibody treatment prevented brain damage caused by E. coli. IL-10 administration elevated CR3 expression in neutrophils and macrophages of infected mice, whereas infected and untreated mice displayed increased expression of FcγRI and TLR2. Neutrophils or macrophages pretreated with IL-10 ex vivo exhibited a significantly greater microbicidal activity against E. coli compared with cells isolated from wild-type or IL-10^−/− mice. The protective effect of IL-10 was abrogated when CR3 was knocked-down in vivo by siRNA. The increased expression of CR3 in phagocytes was caused by inhibition of prostaglandin E-2 (PGE-2) levels, which were significantly increased in neutrophils and macrophages upon E. coli infection. These findings describe a novel modality of IL-10–mediated E. coli clearance by diverting the entry of bacteria via CR3 and preventing PGE-2 formation in neonatal meningitis.

Levels of pro-inflammatory cytokines produced from cord blood in-vitro are pathogen dependent and increased in comparison to adult controls

BACKGROUND

Overproduction of pro-inflammatory cytokines may play a role in increased morbidity and mortality from neonatal sepsis. Objective of this study was to compare secretion of pro-inflammatory cytokines by the cord blood cells of healthy term neonates to the venous blood cells of healthy adults in vitro after stimulation with common neonatal pathogens.

METHOD

Blood samples were cultured in the presence of heat-killed group B beta-hemolytic streptococci (GBS), Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epi). Concentrations of secreted cytokines (interleukine-6, IL-6, tumor necrosis factor-alpha, TNF-alpha, interleukine-1 beta, IL-1beta and interleukine-8, IL-8) were measured after 0, 1, 2 and 4 h of incubation using chemiluminescent immunometric automated assay.

RESULTS

Blood samples from 22 neonates and 16 adults were compared. After stimulation by GBS and E. coli, cord blood cells secreted significantly higher levels of IL-6 and IL-8 than blood cells of healthy adults. In cord blood, E. coli induced secretion of higher concentration of IL-6, TNF-alpha, IL-1beta and IL-8 than S. epi, and more IL-6 than GBS; GBS induced more IL-1beta than S.epi.

CONCLUSIONS

Response of cord blood to microbial activators is different from that of adult controls. Each isolate of heat-killed bacteria induced different amount of pro-inflammatory cytokines in vitro. This may represent a useful in vitro virulence test.

Naturally acquired regulatory mechanism of perioperative cytokine response in neonates

The inflammatory reaction is known to be controlled in neonates. We clarified the characteristics of cytokine profile in neonatal patients and assess its clinical significance. Serum levels of interleukin (IL)-6 and IL-1 receptor antagonist (ra) were determined in 152 pediatric patients and 33 each of maternal and cord bloods. Supernatant IL-1ra levels of cultured monocytes and granulocytes stimulated with IL-1beta or LPS, and IL-1ra mRNA expression of granulocytes were assayed in 15 each of cord and healthy adult bloods. Although surgical stress in neonates was heavier than that in infants, there was no difference in the occurrence of postoperative morbidity and mortality. In neonates, the perioperative serum level of IL-1ra was significantly raised, and the postoperative IL-6 response was well controlled. The serum concentration of IL-1ra in cord blood was not different from that in maternal blood, whereas, the serum concentration of IL-6 in cord blood was significantly reduced than that in maternal blood. In granulocytes, significantly more IL-1ra was produced from cord than from adult blood. An IL-1ra predominant immune status in neonates may be a naturally acquired adaptation system and play a crucial role in attenuating acute inflammatory reaction in a vulnerable host defense.

Bilirubin-induced inflammatory response, glutamate release, and cell death in rat cortical astrocytes are enhanced in younger cells

Unconjugated bilirubin (UCB) encephalopathy is a predominantly early life condition resulting from the impairment of several cellular functions in the brain of severely jaundiced infants. However, only few data exist on the age-dependent effects of UCB and their association with increased vulnerability of premature newborns, particularly in a sepsis condition. We investigated cell death, glutamate efflux, and inflammatory cytokine dynamics after exposure of astrocytes at different stages of differentiation to clinically relevant concentrations of UCB and/or lipopolysaccharide (LPS). Younger astrocytes were more prone to UCB-induced cell death, glutamate efflux, and inflammatory response than older ones. Furthermore, in immature cells, LPS exacerbated UCB effects, such as cell death by necrosis. These findings provide a basis for the increased susceptibility of premature newborns to UCB deleterious effects, namely when associated with sepsis, and underline how crucial the course of cell maturation can be to UCB encephalopathy during moderate to severe neonatal jaundice.

Immature anti-inflammatory response in neonates

The inflammatory response plays a major role in the induction of several neonatal diseases. We hypothesize that an imbalance between the pro- and anti-inflammatory response is crucial for the previously shown enhanced production of proinflammatory cytokines in term and preterm infants during infection. To test this hypothesis, we compared the capacity to produce the main anti-inflammatory cytokines IL-10 and TGF-beta in term infants, preterm infants and adults at different levels of synthesis by quantitative real time reverse-transcribed PCR, flow cytometry, as well as enzyme-linked immunoassay. Term and preterm infants showed a profoundly diminished IL-10 mRNA-expression and IL-10 production after stimulation. In addition, the amount of TGF-beta-positive lymphocytes was significantly less in neonates than adults. Furthermore, there was a considerably lower inhibition of production of IL-1alpha, IL-6, IL-8 and TNF-alpha by the use of recombinant IL-10 in term and preterm infants compared with adults. These results demonstrate not only a diminished anti-inflammatory capacity but also a reduced response to anti-inflammatory stimuli in term and preterm infants. From these data we conclude that neonates display an immature compensatory anti-inflammatory response syndrome (CARS) which may predispose preterm infants to harmful effects of proinflammatory cytokines resulting in severe organ sequelae during infection.

Is interleukin-6 -174 genotype associated with the development of septicemia in preterm infants?

OBJECTIVE

Systemic infection affects one quarter of preterm infants. Defense from infection is in part mediated by the cytokine interleukin-6 (IL-6). We tested the hypothesis that the IL-6 -174 GG genotype, associated with lower IL-6 response to inflammation, is also associated with the development of septicemia in preterm infants.

METHODS

The study group comprised 157 infants who were born at < or =32 weeks. Genotype distribution (34% [54] GG, 46% [72] GC, 20% [31] CC) and C allele frequency (0.43; 95% confidence interval [CI]: 0.37-0.48) were similar to the UK adult population. Among the patients who developed bacterially confirmed septicemia (n = 51 [33%]), there was a significantly higher prevalence of the IL-6 -174 GG genotype than that observed in those who did not develop infection (47% vs 28% for GG: odds ratio [OR]: 2.3; 95% CI: 1.1-4.5). This association remained statistically significant (OR: 2.7; 95% CI: 1.2-6.3) after multiple binary logistic regression adjustment for other significant predictors of the development of septicemia. Late infection alone was similarly associated with GG genotype (septicemia 47% vs no septicemia 29% for GG: OR: 2.2; 95% CI: 1.1-4.3).

CONCLUSIONS

Variation in the IL-6 gene seems to influence the defense against bacterial pathogens in the very preterm infant.

Transient detection of proinflammatory cytokines in sera of colostrum-fed newborn calves

To obtain basic information on the state of proinflammatory cytokines in newborn calves, we determined the kinetics of 5 cytokines (IL-1beta, IL-6, TNF-alpha, IFN-gamma and IL-1 receptor antagonist) in sera of newborns during the first 4 weeks of life. At birth, none of the 5 cytokines were detected in almost all serum samples, but the cytokines became detectable within 12 hr after being fed colostram. The mean concentrations of the cytokines reached peak levels by 24 hr and then gradually decreased and became undetectable by 4 weeks after birth. Cytokine mRNA expressions in peripheral blood mononuclear cells of newborns were observed without reference to the cytokine concentrations in sera. Serum cytokines detected in newborn calves are probably colostral origin.

Ileal cytokine dysregulation in experimental necrotizing enterocolitis is reduced by epidermal growth factor

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of premature infants. We have shown in previous studies that proinflammatory interleukin-18 and interleukin-12 are up-regulated in the ileum of rats with experimental NEC and that epidermal growth factor (EGF) reduces the development of disease. Here we investigated whether the protective effects of EGF are a result of changes in ileal interleukin-18, interleukin-12 and/or antiinflammatory interleukin-10.

METHODS

Newborn rats were artificially fed with either growth-factor-free rat milk substitute (RMS) or RMS supplemented with 500 ng/mL EGF (RMS + EGF) and NEC was induced via exposure to asphyxia and cold stress. Cytokine expression and localization were assessed using reverse-transcription real-time polymerase chain reaction and immunohistology/confocal microscopy.

RESULTS

Enteral administration of EGF (RMS + EGF) decreased overproduction of interleukin-18 and increased interleukin-10 production in the ileum. Furthermore, increased interleukin-10 production was associated with up-regulation of the transcription factor Sp1 in RMS + EGF rats.

CONCLUSIONS

These data suggest that EGF may reduce NEC via increased interleukin-10 and decreased interleukin-18 and that EGF-mediated up-regulation of Sp1 may account for the increased interleukin-10.

Enhanced interleukin-6 and interleukin-8 synthesis in term and preterm infants

There is growing evidence that sepsis-related complications in neonates are crucially mediated by the action of proinflammatory cytokines. It has previously been demonstrated that elevated IL-6 and IL-8 levels can predict brain damage and chronic lung disease in preterm infants. However, it is the current view that neonates have a reduced capability to produce proinflammatory cytokines. To clarify this issue, we analyzed the inflammatory response in term and preterm infants directly at the single cell level by flow cytometry. Endotoxin challenge was performed under defined conditions on monocytes obtained from 50 healthy adults and 119 neonates, which consist of 45 term infants, 63 preterm infants (26.1-36.7 wk of gestational age), and 11 preterm infants with proven infection (24.6-29.9 wk). Our results challenge the existing view of an immature inflammatory response by demonstrating that term infants and preterm infants display a higher percentage of IL-6- and IL-8-positive cells than adults. After preincubation with dexamethasone the number of cytokine-positive cells decreased in all groups, but the number of IL-8-positive cells remained higher in term and preterm infants >32 wk compared with adults. These observations demonstrate not only a well-developed but also an enhanced inflammatory response in term and preterm infants. Under consideration of several detrimental effects of IL-6 and IL-8, our data may have major implications on the pathophysiology of inflammatory-triggered neonatal diseases.

Ureaplasma urealyticum modulates endotoxin-induced cytokine release by human monocytes derived from preterm and term newborns and adults

We previously observed that Ureaplasma urealyticum respiratory tract colonization in infants with a birth weight of < or =1,250 g was associated with increases in the tracheal aspirate proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and interleukin-8 (IL-8) relative to the counterregulatory cytokine IL-6 during the first week of life (A. M. Patterson, V. Taciak, J. Lovchik, R. E. Fox, A. B. Campbell, and R. M. Viscardi, Pediatr. Infect. Dis. J. 17:321-328, 1998). We hypothesized that U. urealyticum alters the host immune response in the presence of a coinflammatory stimulus (e.g., bacterial infection or hyperoxia) by shifting the balance of cytokine expression towards the proinflammatory cytokines. To test this hypothesis, we compared the release of TNF-alpha, IL-8, IL-6, and IL-10 in vitro by unstimulated and U. urealyticum (with or without lipopolysaccharide [LPS])-stimulated human monocytes from adult peripheral blood and from term and preterm cord blood. U. urealyticum alone and in combination with LPS induced concentration- and development-dependent changes in cytokine release. In vitro inoculation with low-inoculum U. urealyticum (10(3) color-changing units [CCU]) (i) partially blocked the LPS-stimulated IL-6 release by all cells and reduced LPS-stimulated IL-10 release by preterm cells, (ii) stimulated TNF-alpha and IL-8 release by preterm cells, and (iii) augmented LPS-stimulated TNF-alpha release in all cells. In preterm cells, high-inoculum U. urealyticum (10(6) CCU) (i) stimulated TNF-alpha and IL-8, but not IL-6 or IL-10, release and (ii) augmented LPS-stimulated TNF-alpha and IL-8 release. High-inoculum U. urealyticum (i) stimulated release of all four cytokines in term cells and IL-8 release in adult cells and (ii) augmented LPS-induced TNF-alpha, IL-10, and IL-8 release in term cells but did not significantly affect LPS-induced cytokine release in adult cells. We speculate that U. urealyticum enhances the proinflammatory response to a second infection by blocking expression of counterregulatory cytokines (IL-6 and IL-10), predisposing the preterm infant to prolonged and dysregulated inflammation, lung injury, and impaired clearance of secondary infections.

Sudden infant death syndrome (SIDS): T-cell immunodeficiency--Part 1

It is hypothesized that SIDS mimics AIDS and atopic eczema in that defective T lymphocytes and overactive B cells overstimulate pro-inflammatory cytokines in the mucosal immune system. Virally infected cells are unable to convert linoleic acid (LA) into gamma-linolenic acid (GLA) which eventually leads to defective T lymphocyte production. Abnormal lung cytokine synthesis by virus-induced immunodeficient T lymphocytes is associated with the murine AIDS-related complex (ARC). Adenosine triphosphate (ATP) deficient anaerobic cells cannot convert LA to GLA. It is hypothesized that, in SIDS victims, elevated levels of hypoxanthine and immunoglobulins are evidence of chronic hypoxemia and ATP catabolism, and an inability to convert LA to GLA, leading to defective T lymphocytes in the mucosal immune system.

Effects of hypothermia and hyperthermia on cytokine production by cultured human mononuclear phagocytes from adults and newborns

We have shown previously that febrile range temperatures modify cytokine production by adult macrophages. In this study, we compared the effects of moderate hyperthermia and hypothermia on the kinetics of lipopolysaccharide (LPS)-induced cytokine expression in monocytes and macrophages of newborns and adults. During culture at 40 degrees C, the initial rates of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) secretion were preserved, but the duration of secretion was shorter than the duration at 37 degrees C. TNF-alpha and IL1-beta concentrations in 24-h 40 degrees C culture supernatants were reduced 18%-50%. IL-6 concentration in 24-h 40 degrees C cultures was reduced 26%-29% in all cells except adult macrophages. At 32 degrees C, changes in early (2 h) and sustained (24 h) cytokine expression were reversed compared with those caused by hyperthermia. Culturing adult macrophages at 32 degrees C blunted early secretion of TNF-alpha and IL-6 by 69% and 65%, respectively, and increased TNF-alpha concentration at 24 h by 48% compared with levels at 37 degrees C. In adult monocytes cultured at 32 degrees C, early IL-6 and IL-1 beta secretion was decreased 64% and 51%, respectively. We speculate that the burst/suppression cytokine profile at febrile temperatures might enhance early activation of host defenses and prevent prolonged exposure to potentially cytotoxic cytokines. Hypothermia, on the other hand, may worsen outcome in infections by delaying and prolonging cytokine production.

Enhancement of neonatal innate defense: effects of adding an N-terminal recombinant fragment of bactericidal/permeability-increasing protein on growth and tumor necrosis factor-inducing activity of gram-negative bacteria tested in neonatal cord blood ex vivo

Innate defense against microbial infection requires the action of neutrophils, which have cytoplasmic granules replete with antibiotic proteins and peptides. Bactericidal/permeability-increasing protein (BPI) is found in the primary granules of adult neutrophils, has a high affinity for lipopolysaccharides (or "endotoxins"), and exerts selective cytotoxic, antiendotoxic, and opsonic activity against gram-negative bacteria. We have previously reported that neutrophils derived from newborn cord blood are deficient in BPI (O. Levy et al., Pediatrics 104:1327-1333, 1999). The relative deficiency in BPI of newborns raised the possibility that supplementing the levels of BPI in plasma might enhance newborn antibacterial defense. Here we determined the effects of addition of recombinant 21-kDa N-terminal BPI fragment (rBPI(21)) on the growth and tumor necrosis factor (TNF)-inducing activity of representative gram-negative clinical isolates. Bacteria were tested in citrated newborn cord blood or adult peripheral blood. Bacterial viability was assessed by plating assay, and TNF-alpha release was measured by enzyme-linked immunosorbent assay. Whereas adult blood limited the growth of all isolates except Klebsiella pneumoniae, cord blood also allowed logarithmic growth of Escherichia coli K1/r and Citrobacter koseri. Bacteria varied in their susceptibility to rBPI(21)'s bactericidal action: E. coli K1/r was relatively susceptible (50% inhibitory concentration [IC(50)], approximately 10 nM), C. koseri was intermediate (IC(50), approximately 1,000 nM), Klebsiella pneumoniae was resistant (IC(50), approximately 10,000 nM), and Enterobacter cloacae and Serratia marcescens were highly resistant (IC(50), >10,000 nM). All isolates were potent inducers of TNF-alpha activity in both adult and newborn cord blood. In contrast to its variable antibacterial activity, rBPI(21) consistently inhibited the TNF-inducing activity of all strains tested (IC(50), 1 to 1,000 nM). The antibacterial effects of rBPI(21) were additive with those of a combination of conventional antibiotics typically used to treat bacteremic newborns (ampicillin and gentamicin). Whereas ampicillin and gentamicin demonstrated little inhibition of bacterially induced TNF release, addition of rBPI(21) either alone or together with ampicillin and gentamicin profoundly inhibited release of this cytokine. Thus, supplementing newborn cord blood with rBPI(21) potently inhibited the TNF-inducing activity of a variety of gram-negative bacterial clinical pathogens and, in some cases, enhanced bactericidal activity. These results suggest that administration of rBPI(21) may be of clinical benefit to neonates suffering from gram-negative bacterial infection and/or endotoxemia.

Effect of nitric oxide donors and nitric oxide synthase inhibitors in neonatal rat endotoxic shock

Previous studies have shown an increased mortality in response to endotoxin in 24-hr-old neonatal rats compared with older neonates and adults. This increased susceptibility may be related to increased nitric oxide (NO) and thromboxane (TxB2) production. Twenty-four-hour-old neonatal rat pups were given either N(G)-nitro-L-arginine methyl ester (L-NAME; a nonspecific NO synthase inhibitor), S-methylthioisourea (SMT; a specific NO synthase inhibitor), or molsidomine (a NO donor) subcutaneously prior to or after an LD50 of intracardiac endotoxin. Mortality was followed for 72 hr. There was no statistically significant difference in mortality between control animals and those pretreated with L-NAME, SMT, or molsidomine. A trend toward increased mortality with nonspecific NO synthase inhibition and decreased mortality with the NO donor was noted. Splenic cells were obtained for in vitro cytokine stimulation studies. In vitro adherent splenic cell stimulation studies confirmed an increase in NO production with NO donor pretreatment and decreased production of NO with NO synthase inhibition pretreatment. There was no difference in TxB2 production with either the NO synthase inhibitor or the NO donor. In conclusion, at the several doses employed, neither nonselective or selective NO synthase inhibitors nor NO donors prevented endotoxin-induced mortality in rat neonatal shock. Although these findings do not preclude possible involvement of NO in neonatal pathophysiology, increased NO production thus does not appear to be the primary determinant of the increased susceptibility of the neonatal rat to endotoxic shock.

Neuroendocrine-immune interactions in the neonate

Cytokine responses to lipopolysaccharides in neuroendocrine tissues are age- and tissue-dependent in neonatal pigs. Developmental differences in serum and tissue-specific responses are not necessarily equivalent. Lower levels of cytokine gene expression in neuroendocrine tissues of early neonates potentially could influence neuroendocrine and immune responses to infection. The limited information on neuroendocrine-immune responses and interactions in neonatal farm animals presents significant challenges, as well as opportunities for new discoveries and improvements of livestock production.

Endotoxemia and tumor necrosis factor activity in dogs with naturally occurring parvoviral enteritis

A prospective, nonrandomized study was performed to evaluate the role of endotoxin and tumor necrosis factor (TNF) in dogs with parvoviral enteritis. Seventeen dogs with naturally occurring parvoviral enteritis were enrolled in the study. Plasma samples were obtained for quantification of endotoxin and TNF on presentation and at 3 and 6 hours after therapy with either fluids prior to antibiotics, or fluids concurrently with antibiotics. All dogs received standard supportive therapy. Fourteen of 17 dogs had endotoxin in their plasma during the study period; 7 of 17 dogs had measurable TNF. No endotoxin or TNF was detectable in plasma from normal puppies. An increase in TNF activity was predictive of mortality (P = .041). There was a trend for increasing endotoxin activity to predict mortality (P = .0769). Animals that received antibiotics with fluids were significantly older than those that received fluids prior to antibiotics, and there was a trend for animals that received antibiotics with fluids to have a decrease in endotoxin activity after treatment (P = .054). Endotoxin and activation of the cytokine cascade are integral to the pathophysiology of parvoviral enteritis. Measures to limit endotoxemia and the systemic inflammatory response may improve survival.