Neonatal dexamethasone treatment induces long-lasting changes in T-cell receptor vbeta repertoire in rats

Effect of betamethasone, indomethacin and fenoterol on neonatal and maternal mononuclear cells stimulated with Escherichia coli

Despite considerable progress in the field of perinatal care, infectious diseases, especially when caused by gram negative bacteria, remain a major reason for neonatal morbidity and mortality. Notably infants born prematurely and those with very low birth weight are at risk due to their immature and deficient immune system and their prolonged hospitalization which promotes nosocomial infections. In case of impending preterm birth, betamethasone is given to induce lung maturation and tocolytic agents like indomethacin or fenoterol are administered to suppress premature labor. The aim of this study was to analyze the effects of these drugs on the immune system of mothers and neonates. Therefore, mononuclear cells from cord blood and peripheral maternal blood were stimulated with Escherichia coli and incubated with betamethasone, indomethacin and fenoterol. Subsequently the effect of the treatment on cytokine production was determined. Betamethasone alone and in combination with tocolytic agents inhibited the production of pro- and anti-inflammatory cytokines. Not only does betamethasone dampen the immune response by reducing the production of cytokines, it also has a variety of other detrimental short- and long-term effects on the neonate. In conclusion we would recommend using biological markers to determine if premature labor actually leads to preterm birth and subsequently administer betamethasone only to mothers giving birth prematurely.

A novel model to study neonatal Escherichia coli sepsis and the effect of treatment on the human immune system using humanized mice

PROBLEM

Neonatal sepsis is a serious threat especially for preterm infants. As existing in vitro and in vivo models have limitations, we generated a novel neonatal sepsis model using humanized mice and tested the effect of Betamethasone and Indomethacin which are used in the clinic in case of premature birth.

METHOD OF STUDY

Humanized mice were infected with Escherichia coli (E. coli). Subsequently, the effect of the infection itself, and treatment with Betamethasone and Indomethacin on survival, recovery, bacterial burden, leukocyte populations, and cytokine production, was analyzed.

RESULTS

The human immune system in the animals responded with leukocyte trafficking to the site of infection and granulopoiesis in the bone marrow. Treatment with Indomethacin had no pronounced effect on the immune system or bacterial burden. Betamethasone induced a decline of splenocytes.

CONCLUSION

The human immune system in humanized mice responds to the infection, making them a suitable model to study neonatal E. coli sepsis and the immune response of the neonatal immune system. Treatment with Betamethasone could have potential negative long-term effects for the immune system of the child.

Prenatal Administration of Betamethasone Causes Changes in the T Cell Receptor Repertoire Influencing Development of Autoimmunity

Prenatal glucocorticoids are routinely administered to pregnant women at risk of preterm delivery in order to improve survival of the newborn. However, in half of the cases, birth occurs outside the beneficial period for lung development. Glucocorticoids are potent immune modulators and cause apoptotic death of immature T cells, and we have previously shown that prenatal betamethasone treatment at doses eliciting lung maturation induce profound thymocyte apoptosis in the offspring. Here, we asked if there are long-term consequences on the offspring’s immunity after this treatment. In the non-obese diabetic mouse model, prenatal betamethasone clearly decreased the frequency of pathogenic T cells and the incidence of type 1 diabetes (T1D). In contrast, in the lupus-prone MRL/lpr strain, prenatal glucocorticoids induced changes in the T cell repertoire that resulted in more autoreactive cells. Even though glucocorticoids transiently enhanced regulatory T cell (Treg) development, these cells did not have a protective effect in a model for multiple sclerosis which relies on a limited repertoire of pathogenic T cells for disease induction that were not affected by prenatal betamethasone. We conclude that prenatal steroid treatment, by inducing changes in the T cell receptor repertoire, has unforeseeable consequences on development of autoimmune disease. Our data should encourage further research to fully understand the consequences of this widely used treatment.

Ovine fetal thymus response to lipopolysaccharide-induced chorioamnionitis and antenatal corticosteroids

Rationale

Chorioamnionitis is associated with preterm delivery and involution of the fetal thymus. Women at risk of preterm delivery receive antenatal corticosteroids which accelerate fetal lung maturation and improve neonatal outcome. However, the effects of antenatal corticosteroids on the fetal thymus in the settings of chorioamnionitis are largely unknown. We hypothesized that intra-amniotic exposure to lipopolysaccharide (LPS) causes involution of the fetal thymus resulting in persistent effects on thymic structure and cell populations. We also hypothesized that antenatal corticosteroids may modulate the effects of LPS on thymic development.

Methods

Time-mated ewes with singleton fetuses received an intra-amniotic injection of LPS 7 or 14 days before preterm delivery at 120 days gestational age (term = 150 days). LPS and corticosteroid treatment groups received intra-amniotic LPS either preceding or following maternal intra-muscular betamethasone. Gestation matched controls received intra-amniotic and maternal intra-muscular saline. The fetal intra-thoracic thymus was evaluated.

Results

Intra-amniotic LPS decreased the cortico-medullary (C/M) ratio of the thymus and increased Toll-like receptor (TLR) 4 mRNA and CD3 expression indicating involution and activation of the fetal thymus. Increased TLR4 and CD3 expression persisted for 14 days but Foxp3 expression decreased suggesting a change in regulatory T-cells. Sonic hedgehog and bone morphogenetic protein 4 mRNA, which are negative regulators of T-cell development, decreased in response to intra-amniotic LPS. Betamethasone treatment before LPS exposure attenuated some of the LPS-induced thymic responses but increased cleaved caspase-3 expression and decreased the C/M ratio. Betamethasone treatment after LPS exposure did not prevent the LPS-induced thymic changes.

Conclusion

Intra-amniotic exposure to LPS activated the fetal thymus which was accompanied by structural changes. Treatment with antenatal corticosteroids before LPS partially attenuated the LPS-induced effects but increased apoptosis in the fetal thymus. Corticosteroid administration after the inflammatory stimulus did not inhibit the LPS effects on the fetal thymus.

Interplay between Depressive-Like Behavior and the Immune System in an Animal Model of Prenatal Dexamethasone Administration

Glucocorticoids, namely dexamethasone, are prescribed during late gestation in pregnancies at risk of originating premature newborns, to promote fetal lung maturation. However, adverse early life events have been reported to induce long-lasting changes in the immune and central nervous systems. The accumulating evidence on bidirectional interactions between both systems in psychiatric disorders like depression, prompted us to further investigate the long-term impact of prenatal dexamethasone administration in depressive-like behavior, the immune system and in the ability to mount an immune response to acute infection. The adult male offspring of pregnant dams treated with dexamethasone present depressive-like behavior concomitant with a decrease in CD8(+) T lymphocytes and an increase in B and CD4(+) regulatory T cells. This is accompanied by lower levels of serum interleukin-6 (IL-6) and IL-10. Despite of these differences, when spleen cells are stimulated, in vitro, with lipopolysaccharide, those from adult rats prenatally treated with dexamethasone display a stronger pro-inflammatory cytokine response. However, this immune system profile does not hamper the ability of rats prenatally treated with dexamethasone to respond to acute infection by Listeria monocytogenes. Of notice, L. monocytogenes infection triggers depressive-like behavior in control animals but does not worsen that already present in dexamethasone-treated animals. In summary, prenatal administration of dexamethasone has long-lasting effects on the immune system and on behavior, which are not further aggravated by acute infection with L. monocytogenes.

Neonatal maternal separation alters immune, endocrine, and behavioral responses to acute Theiler's virus infection in adult mice

Previous studies have established a link between adverse early life events and subsequent disease vulnerability. The present study assessed the long-term effects of neonatal maternal separation on the response to Theiler's murine encephalomyelitis virus infection, a model of multiple sclerosis. Balb/cJ mouse pups were separated from their dam for 180-min/day (180-min MS), 15-min/day (15-min MS), or left undisturbed from postnatal days 2-14. During adolescence, mice were infected with Theiler's virus and sacrificed at days 14, 21, or 35 post-infection. Prolonged 180-min MS increased viral load and delayed viral clearance in the spinal cords of males and females, whereas brief 15-min MS increased the rate of viral clearance in females. The 15-min and 180-min MS mice exhibited blunted corticosterone responses during infection, suggesting that reduced HPA sensitivity may have altered the immune response to infection. These findings demonstrate that early life events alter vulnerability to CNS infection later in life. Therefore, this model could be used to study gene-environment interactions that contribute to individual differences in susceptibility to infectious and autoimmune diseases of the CNS.

Maternal and early life stress effects on immune function: relevance to immunotoxicology

Stress is triggered by a variety of unexpected environmental stimuli, such as aggressive behavior, fear, forced physical activity, sudden environmental changes, social isolation or pathological conditions. Stressful experiences during very early life (particularly, maternal stress during fetal ontogeny) can permanently alter the responsiveness of the nervous system, an effect called programming or imprinting. Programming affects the hypothalamic-pituitary-adrenocortical (HPA) axis, brain neurotransmitter systems, sympathetic nervous system (SNS), and the cognitive abilities of the offspring, which can alter neural regulation of immune function. Prenatal or early life stress may contribute to the maladaptive immune responses to stress that occur later in life. This review focuses on the effect of maternal and early life stress on immune function in the offspring across life span. It highlights potential mechanisms by which prenatal stress impacts immune functions over life span. The literature discussed in this review suggests that psychosocial stress during pre- and early postnatal life may increase the vulnerability of infants to the effects of immunotoxicants or immune-mediated diseases, with long-term consequences. Neural-immune interactions may provide an indirect route through which immunotoxicants affect the developing immune system. A developmental approach to understanding how immunotoxicants interact with maternal and early life stress-induced changes in immunity is needed, because as the body changes physiologically across life span so do the effects of stress and immunotoxicants. In early and late life, the immune system is more vulnerable to the effects of stress. Stress can mimic the effects of aging and exacerbate age-related changes in immune function. This is important because immune dysregulation in the elderly is more frequently and seriously associated with clinical impairment and death. Aging, exposure to teratogens, and psychological stress interact to increase vulnerability and put the elderly at the greatest risk for disease.

Effects of neonatal dexamethasone or methylprednisolone on rat growth and neurodevelopment

BACKGROUND

Clinical studies have demonstrated that premature infants receiving long-term dexamethasone therapy have reduced linear growth, decreased weight gain, and smaller head circumferences. The purpose of the present study was to investigate the effects of the same equivalent doses for anti-inflammatory potency of neonatal dexamethasone and methylprednisolone on rat growth and neurodevelopment.

METHODS

The pups were randomly separated into three treatment groups on postnatal day (PD) 3. At postnatal 3-5 days, tapering doses of corticosteroids or sterile saline were administered subcutaneously. Group 1 was the dexamethasone group (n = 12; PD 3, 0.5 mg/kg; PD 4, 0.25 mg/kg; PD 5, 0.125 mg/kg; PD 6, 0.05 mg/kg s.c.); group 2, methylprednisolone group (n = 12; PD 3, 2.6 mg/kg; PD 4, 1.3 mg/kg; PD 5, 0.650 mg/kg; PD 6, 0.325 mg/kg; group 3, control group (n = 12; normal saline injected). Weight was recorded on PD 3-6, 8, 14, 22, length was recorded on PD 3, 7, 14, 21 for each group. Neurological responses and physical development were tested on PD 7, 14, 21.

RESULTS

On PD 4-6, 8, 14, 22 the weight in the dexamethasone and methylprednisolone groups was lower than in the control group, but the weight in the dexamethasone group was the lowest (P < 0.05). The length in the dexamethasone group was significantly shorter than in the methylprednisolone group on PD 14 and 21. Dexamethasone-treated animals had a reduced total neurological score compared with the methylprednisolone and control groups on PD 7, 14, 21. Although methylprednisolone-treated animals had lower total neurological score than that of the control group on PD 7 and PD 14 (P < 0.05), total neurological scores were not different in the methylprednisolone and control groups on PD 21.

CONCLUSIONS

Postnatal methylprednisolone treatment might be safer than dexamethasone treatment in newborns.

Neonatal dexamethasone treatment for chronic lung disease of prematurity alters the hypothalamus-pituitary-adrenal axis and immune system activity at school age

OBJECTIVE

To compare long-term effects of neonatal treatment with dexamethasone or hydrocortisone for chronic lung disease of prematurity on the hypothalamus-pituitary-adrenal axis and the immune response in children at school age.

PATIENTS AND METHODS

A total of 156 prematurely born children were included in this retrospective matched cohort study. Children treated with dexamethasone (n = 52) or hydrocortisone (n = 52) were matched for gestational age, birth weight, grade of infant respiratory distress syndrome, grade of periventricular or intraventricular hemorrhage, gender, and year of birth. A reference group of 52 children not treated with corticosteroids was included for comparison. Plasma adrenocorticotropic hormone and cortisol in response to a social stress task were determined. Cytokine production was analyzed after in vitro stimulation of whole-blood cultures.

RESULTS

The Trier Social Stress Test adapted for children induced an adrenocorticotropic hormone and cortisol response in all of the groups. The adrenocorticotropic hormone response was blunted in the dexamethasone group. The overall cortisol level was lower in the dexamethasone than in the hydrocortisone and reference group. Cortisol and adrenocorticotropic hormone in the hydrocortisone and reference groups were similar. The ratio of T-cell mitogen-induced interferon-gamma/interleukin-4 secretion was significantly higher in the dexamethasone group than in the hydrocortisone group. Interferon-gamma production and the ratios of interferon-gamma/interleukin-4 and interferon-gamma/ interleukin-10 were significantly higher in the dexamethasone group than the reference group. However, production of these cytokines did not differ between the hydrocortisone and the reference groups.

CONCLUSION

Neonatal treatment of prematurely born children with dexamethasone but not with hydrocortisone resulted in long-lasting programming effects on hypothalamus-pituitary-adrenal axis and on the T-helper 1/T-helper 2 cytokine balance. Follow-up of these children is required to investigate long-term clinical consequences. We recommend that authors of previously performed randomized, controlled trials on neonatal glucocorticoid treatment include immune and neuroendocrine analyses in prolonged follow-up of these children.

Characterization of T-cell population in children with prolonged fetal exposure to dexamethasone for anti-Ro/SS-A antibodies associated congenital heart block

The objectives of the study were to characterize the production, function and survival of T lymphocytes of children with prolonged fetal exposure to dexamethasone for anti-Ro/SS-A antibodies associated congenital complete heart block. The analysis of thymic function, studied by measuring the level of T-cell receptor excision circles, was performed by real time PCR, the composition of T-cell subpopulation was evaluated by flow cytometry and the T-cell diversity was assayed by heteroduplex analysis. T-cell competence was gauged at two functional levels by determining the proliferation and the number of T-cell divisions and by measuring gamma-interferon production after mitogenic stimulation. We observed that the thymic output, distribution of T-cell subsets, thymidine incorporation, number of T-cell divisions, and y-interferon production were comparable to those of age-matched control. On the contrary, heteroduplex analysis demonstrated the presence of both polyclonal and oligoclonal peripheral T-cell repertoires. In conclusion, the analysis of the T-cell compartment in children with prolonged intrauterine exposure to high dose dexamethasone did not disclose any relevant abnormality, except a restriction of T-cell receptor diversity in some patients.

The long-term effects of perinatal glucocorticoid exposure on the host defence system of the respiratory tract

Glucocorticoids are used to mature the fetal lung at times of threatened premature delivery. These drugs modify leukocyte profiles when administered in adulthood, but their effects on the mature host defence system following administration during the perinatal period are incompletely understood. In this study, the long-term effects of perinatal dexamethasone exposure on rodent host defence cells in the pulmonary airspaces, the perivascular compartment of the lung, and the blood were investigated. Rats were treated prenatally (gestational days 16-19) or neonatally (postnatal days 1-7) by inclusion of dexamethasone in the mothers' drinking water (1 microg/ml). The pups were then allowed to develop to adulthood (P60-80), at which time respiratory tissues were collected for light and electron microscopy and bronchoalveolar lavage (BAL), and blood for cell count and fluorescent activated cell-sorting (FACS) analysis. Prenatal treatment had no effect on any parameter examined. Following neonatal dexamethasone exposure, light microscopy of the lung tissue revealed a significant reduction in the number of cells in the perivascular space in both the central and the peripheral regions of the adult lung, but no differences in the number of cells in the airspaces. Neonatal dexamethasone exposure was also characterized by a significant reduction in the total number of white cells in the peripheral blood in adulthood and in particular, the number of lymphocytes relative to neutrophils was significantly reduced at maturity in these animals. The results show that neonatal, but not prenatal, dexamethasone exposure significantly alters the distribution of host defence cells in the blood and lung at maturity compared with control animals. The early neonatal period is characterized by the stress hyporesponsive period in the rat, when endogenous glucocorticoid levels are very low. Therefore, exogenous glucocorticoids administered during this time are likely to have marked "programming" effects on glucocorticoid-sensitive tissues.

Different roles for glucocorticoids in thymocyte homeostasis?

Glucocorticoids (GCs) have important immunoregulatory effects on thymocytes and T cells. Ectopic production of GCs has been demonstrated in thymic epithelial cells (TECs) but the role of GCs in thymocyte homeostasis is controversial. Studies in several different mouse models, genetically modified for the GC receptor (GR) expression or function, have demonstrated conflicting results in terms of the effect of the hormone on thymocytes. Here, we summarize these data and suggest that GCs can mediate both positive and negative effects in the organ depending on the local hormonal concentration. Basal GC levels might promote growth of early thymocytes in young mice, and increased levels, generated through a stress reaction, apoptosis in these cells. A gradual loss of GC synthesis in TECs during aging might contribute to thymic involution, a process so far unexplained.

Effect of dexamethasone on B7 regulation and T cell activation in neonates and adults

The safety of dexamethasone for neonates has been questioned, partly because of its multiple unspecific effects on the immune system. Specific effects of dexamethasone on co-stimulatory and immune suppressive functions of neonatal compared with adult macrophages (MPhi) are not known. We evaluated the effect of dexamethasone on the expression and regulation of MPhi B7 family receptors (B7-1, CD80; B7-2, CD86) and on their ability to co-stimulate T cells. Cord blood macrophages (CBMPhi) and MPhi from healthy adults (PBMPhi) were isolated, and cell surface markers were phenotyped by flow cytometry. In tissue culture, cells were exposed to dexamethasone, interferon-gamma (IFN-gamma), cAMP, or a T cell mitogen (alphaCD3) and examined for their capacity to activate or destroy T cells. CBMPhi were less able to up-regulate CD80 and CD86 than PBMPhi (p < 0.05). Dexamethasone inhibited the up-regulation of CD80, CD86, and HLA-DR on PBMPhi and even more so on CBMPhi (p < 0.05 versus PBMPhi for CD80 and CD86). In the presence of dexamethasone, stimulation with alphaCD3 MAb enhanced cytotoxic functions of PMBMPhi and CB(mu)phi with an increase in deleted T cells, a reduced fraction of enlarged T cells, and an inhibition of T cell CD28 up-regulation, which again were more pronounced with CBMPhi (p < 0.05 versus PBMPhi). In conclusion, neonatal MPhi are exquisitely sensitive to the inhibitory effects of dexamethasone on B7 expression. Although perhaps producing the desired therapeutic effect, dexamethasone may do so in newborns at the expense of a near complete paralysis of MPhi-dependent T cell function.

Effect of neonatal dexamethasone exposure on growth and neurological development in the adult rat

Until recently, the synthetic glucocorticoid dexamethasone was commonly used to lessen the morbidity of chronic lung disease in premature infants. This practice diminished as dexamethasone use was linked to an increased incidence of cerebral palsy and short-term neurodevelopmental delay. Of more concern is the fact that we know little regarding dexamethasone effects on long-term neurodevelopment. To study the effects of neonatal dexamethasone exposure on long-term neurodevelopment, we have developed a rat model where newborn pups are exposed to tapering doses of dexamethasone at time points corresponding to the neurodevelopmental age when human infants are traditionally exposed to this drug in the neonatal intensive care unit. Using a within-litter design, pups were assigned to one of three groups on postnatal day 2 (P2): handled controls, saline-injected controls, and animals receiving intramuscular dexamethasone between P3 and P6. Somatic growth was decreased in dexamethasone-treated animals. Dexamethasone-treated animals demonstrated slight delays in indexes of neurodevelopment and physical maturation at P7 and P14, but not P20. In adolescence (P45), there was no difference between groups in an open field test. However, as adult dexamethasone-treated animals were less active in the open field and spent more time in closed arms of the elevated plus maze. The serum corticosterone response to crowding stress in dexamethasone-treated animals was no different from controls, but they demonstrate a delay in return of corticosterone levels to baseline. These differences in behavior and hormonal stress responsiveness suggest that neonatal dexamethasone exposure may permanently alter function of the neuroendocrine stress axis.

Increased expression of TCR vbeta5.1 and 8 in mucosal T-cell lines cultured from patients with Crohn disease

BACKGROUND

Characterization of the T-cell receptor variable beta chain (Vbeta) repertoire in inflamed mucosa has been used to identify disease-relevant T-cell populations and antigens in Crohn disease (CD). In vitro expansion of mucosal T cells may reveal changes in Vbeta repertoire not apparent in fresh isolates and we aimed to identify Vbeta subpopulations implicated in Crohn disease.

METHODS

In vivo activated mucosal T cells were cultivated using IL-2 and IL-4 from biopsies of whole colonic mucosa without use of Vbeta-modifying exogenous antigen or feeder cells. The Vbeta gene expression in mucosal T-cell cultures was determined in 30 patients with CD and 12 healthy controls using reverse transcriptase polymerase reaction (RT-PCR) covering all 23 functional Vbeta families and the Vbeta receptor prevalence was evaluated by flow cytometry in selected cultures.

RESULTS

Early T-cell cultures from both CD patients and healthy controls showed a polyclonal Vbeta gene expression that narrowed during culture, which in CD cultures led to a significant over-expression of the Vbeta5.1 (P = 0.04) and Vbeta8 gene segments (P = 0.03). Together with Vbeta6 and Vbeta18, these Vbeta chains form a pattern of staphylococcal enterotoxin type E (SEE) responsive Vbeta chains, also over-expressed in CD cultures (P = 0.02). Further in vitro stimulation of CD cultures with SEE caused expansion of Vbeta8 receptor positive cells together with a proinflammatory cytokine response.

CONCLUSIONS

CD may be associated with (super)antigen-specific Vbeta subpopulations selected during long-term cultivation of mucosal biopsies from inflamed colon.

Cardiac transplantation for hypoplastic left heart syndrome

Future improvements can be expected in cardiac transplantation in children. We continue to advance our understanding of the immune system, and to develop more specific immunosuppressive agents. Ultimately, the future for recipients may be improved by strategies such as induction therapy or donor-derived chimeric destined transfusions, designed to enhance the tolerance of the host to a human leukocyte antigen incompatible graft. Improvements in tolerance of the host would allow for reduction or elimination of many, if not all, of the immunosuppressive agents, and for longevity extending well into the adulthood. Survival, particularly for infants, has improved dramatically in the last decade. The most recent results from the registry of the International Society of Heart and Lung Transplantation/United Network for Organ Sharing show that recipients less than one year old at transplantation, who survive the first year, have greater than a 95% survival to four years (Fig. 1). As late outcomes continue to improve, transplantation will provide a better quality and duration of life for infants with hypoplastic left heart syndrome. It is possible, nonetheless, that some infants will require retransplantation, since the half life of a transplanted heart in children has been about 12 years. The alternative is conventional surgery with multiple palliative operations, and the need for later transplantation as end-stage cardiac function is reached. Efforts to increase potential donors and donor utilization can be supported by innovative schemes, such as ABO incompatible transplants. Additional efforts are made more urgent when the current data indicate excellent outcomes after transplantation, but a high mortality while waiting for transplantation.

Maternal deprivation of rat pups increases clinical symptoms of experimental autoimmune encephalomyelitis at adult age

Maternal deprivation of neonatal animals has been shown to induce long-lasting changes in the reactivity of the neuroendocrine system. The aim of the present study was to investigate whether maternal deprivation also affects susceptibility to immune-mediated diseases such as experimental autoimmune encephalomyelitis (EAE) in adult life. To this end, 9-day-old rat pups were subjected to a short-lasting maternal deprivation for a period of 24 h. At the age of 8 weeks, we induced EAE in these rats by immunization with myelin basic protein (MBP) in complete Freund's adjuvant. Our data demonstrate that short-lasting maternal deprivation induces a marked increase in the severity of EAE in the animals in later life. The histopathological evaluation of spinal cord and cerebellum corresponded with the observed differences in clinical symptoms of EAE. Moreover, neonatal maternal deprivation affects macrophage functioning at adult age. In contrast, no differences were observed in in vitro mitogen- and MBP-induced cytokine production by splenocytes. LPS-induced corticosterone release did not differ either between maternally deprived and control animals. We conclude that short-lasting neonatal maternal deprivation of rat pups has long-lasting consequences for macrophage activity and for susceptibility to the inflammatory autoimmune disease EAE.

Early life environment: does it have implications for predisposition to disease?

Early life environmental factors have been associated with altered predisposition to a variety of pathologies. A considerable literature examines pre- and postnatal factors associated with increased risk of cardiovascular, metabolic (i.e. insulin resistance, hyperlipidemia) and psychiatric disease, and the importance of hormonal programming. The brain is exquisitely sensitive to environmental inputs during development and the stress responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis has been shown to be both up- and down-regulated by early life exposure to limited nutrition, stress, altered maternal behaviors, synthetic steroids and inflammation. It has been suggested that peri-natal programming of HPA axis regulation might therefore contribute to metabolic and psychiatric disease etiology. In addition, glucocorticoids play modulatory roles regulating many aspects of immune function, notably controlling both acute and chronic inflammatory responses. Neuroendocrine-immune communication is bidirectional, and therefore it is expected that environmental factors altering HPA regulation have implications for stress effects on immune function and predisposition to inflammation. The impact of pre- and postnatal factors altering immune function, stress responsivity and predisposition to inflammatory disease are reviewed. It is also examined whether the early 'immune environment' might similarly influence predisposition to disease and alter neuroendocrine function. Evidence indicating a role for early life inflammation and infection as an important factor programming the neuroendocrine-immune axis and altering predisposition to disease is considered.

Pediatric heart transplantation

Heart transplantation is now a treatment option with good outcome for infants and children with end-stage heart failure or complex, inoperable congenital cardiac defects. One-year and 5-year actuarial survival rates are high, approximately 75% and 65%, respectively, with overall patient survival half-life greater than 10 years. To date, survival has been improving as a result of reducing early mortality. Further reductions in late mortality, in part because of graft coronary artery disease and rejection, will allow achievement of the goal of decades-long survival. Quality of life in surviving children, as judged by activity, is usually "normal." Somatic growth is usually at the low normal range but linear growth can be reduced. Of infant recipients, 85% evaluated at 6 years of age or older were in an age-appropriate grade level. Long-term management of childhood heart recipients requires the collaboration of transplant physicians, given the increasing number of immunosuppressive agents and the balance between rejection and infection. Currently, recipients are maintained on immunosuppressive medications that target calcineurin (eg, cyclosporine, tacrolimus), lymphocyte proliferation (eg, azathioprine, mycophenolate mofetil [MMF], sirolimus) and, in some instances antiinflammatory corticosteroids. Emerging evidence now suggests a favorable immunologic opportunity for transplantation in childhood and, conversely, a higher mortality rate in children who have had prior cardiac surgery. Further studies are needed to define age-dependent factors that are likely to play a role in graft survival and possible graft-specific tolerance (eg, optimal conditions for tolerance induction and how immunosuppressive regimens should be changed with maturation of the immune system). As late outcomes continue to improve, the need for donor organs likely will increase, as transplantation affords a better quality and duration of life for children with complex congenital heart disease, otherwise facing a future of multiple palliative operations and chronic heart failure.