Prenatal exposure to a pro-inflammatory stimulus causes delays in the development of the innate immune response to LPS in the offspring

Interleukin-6 produces behavioral deficits in pre-pubescent mice independent of neuroinflammation

Maternal inflammation during pregnancy increases the offspring's risk of developing autism, ADHD, schizophrenia, and depression. Epidemiologic studies have demonstrated that maternal infections stimulate the production of interleukin-6 (IL-6), which can cross the placenta and fetal blood-brain barrier to alter brain development with functional and behavioral consequences. To model the effects of increased IL-6 between weeks 24-30 of human gestation, we injected male and female mice with 75 ng IL-6 twice daily, from P3 to P6. Our published studies have shown that this increases circulating IL-6 two-fold, alters post-pubescent ultrasonic vocalization patterns, reduces sociability, and increases self-grooming. However, most neurodevelopmental disorders in humans manifest in children as young as 2 years of age. Hence, a critical unexplored question is whether behavioral changes in immune activation models can be detected in pre-pubescent mice. Therefore, we evaluated early communication, sociability, and repetitive behaviors in pre-pubescent mice following the IL-6 treatment. A second open question is whether the cellular and behavioral changes are secondary to systemic or neuroinflammation. To address this question, we profiled 18 cytokines and chemokines in the circulation and CNS and evaluated eight immune cell types in P7 male and female brains following systemic IL-6 administration. We found an increase in ultrasonic vocalizations with simpler morphologies produced by the IL-6-injected male pups and a decrease in frequency in the female vocalizations upon removal from the nest at P7. The IL-6-treated male pups also socially interacted less when introduced to a novel mouse vs. controls as juveniles and spent almost twice as much time grooming themselves, a phenotype not present in the females. Tactile sensitivity was also increased, but only in the IL-6-treated female mice. The IL-6-treated mice had increased circulating IL-6 and IL-7 and reduced IL-13 at P7 that were no longer elevated at P14. There were no changes in brain levels of IL-6, IL-10, IL-13 or IL-17A mRNAs at P7. Altogether, these studies show that changes in the three core behavioral domains associated with several psychiatric disorders can be detected early in pre-pubescent mice following a transient developmental increase in IL-6. Yet, these behavioral alterations do not require neuroinflammation.

Influence of Immune System Abnormalities Caused by Maternal Immune Activation in the Postnatal Period

The developmental origins of health and disease (DOHaD) indicate that fetal tissues and organs in critical and sensitive periods of development are susceptible to structural and functional changes due to the adverse environment in utero. Maternal immune activation (MIA) is one of the phenomena in DOHaD. Exposure to maternal immune activation is a risk factor for neurodevelopmental disorders, psychosis, cardiovascular diseases, metabolic diseases, and human immune disorders. It has been associated with increased levels of proinflammatory cytokines transferred from mother to fetus in the prenatal period. Abnormal immunity induced by MIA includes immune overreaction or immune response failure in offspring. Immune overreaction is a hypersensitivity response of the immune system to pathogens or allergic factor. Immune response failure could not properly fight off various pathogens. The clinical features in offspring depend on the gestation period, inflammatory magnitude, inflammatory type of MIA in the prenatal period, and exposure to prenatal inflammatory stimulation, which might induce epigenetic modifications in the immune system. An analysis of epigenetic modifications caused by adverse intrauterine environments might allow clinicians to predict the onset of diseases and disorders before or after birth.

Developmental programming of macrophages by early life adversity

Macrophages are central elements of all organs, where they have a multitude of physiological and pathological functions. The first macrophages are produced during fetal development, and most adult organs retain populations of fetal-derived macrophages that self-maintain without major input of hematopoietic stem cell-derived monocytes. Their developmental origins make macrophages highly susceptible to environmental perturbations experienced in early life, in particular the fetal period. It is now well recognized that such adverse developmental conditions contribute to a wide range of diseases later in life. This chapter explores the notion that macrophages are key targets of environmental adversities during development, and mediators of their long-term impact on health and disease. We first briefly summarize our current understanding of macrophage ontogeny and their biology in tissues and consider potential mechanisms by which environmental stressors may mediate fetal programming. We then review evidence for programming of macrophages by adversities ranging from maternal immune activation and diet to environmental pollutants and toxins, which have disease relevance for different organ systems. Throughout this chapter, we contemplate appropriate experimental strategies to study macrophage programming. We conclude by discussing how our current knowledge of macrophage programming could be conceptualized, and finally highlight open questions in the field and approaches to address them.

Balance of Drug Residence and Diffusion in Lacrimal Fluid Determine Ocular Bioavailability in In Situ Gels Incorporating Tranilast Nanoparticles

We previously designed ophthalmic formulations (nTRA) containing tranilast nanoparticles (Tra-NPs) with high uptake into ocular tissues. In this study, we used in situ gel (ISG) bases comprising combinations of pluronic F127 (F127) and methylcellulose (MC/F127), pluronic F68 (F68/F127), and Carbopol (Car/F127), and we developed in situ gels incorporating Tra-NPs (Tra-NP-incorporated ISNGs) such as nTRA-F127, nTRA-MC/F127, nTRA-F68/F127, and nTRA-Car/F127. Moreover, we demonstrated the therapeutic effect on conjunctival inflammation using lipopolysaccharide-induced rats. Each Tra-NP-incorporated ISNG was prepared by the bead mill method, the particle size was 40–190 nm, and the tranilast release and diffusion from formulation were nTRA > nTRA-F127 > nTRA-F68/F127 > nTRA-Car/F127 > nTRA-MC/F127. In the Tra-NP-incorporated ISNGs, the tranilast residence time in the lacrimal fluid, cornea, and conjunctiva was prolonged, although the C_max was attenuated in comparison with nTRA. On the other hand, no significant difference in conjunctival inflammation between non- and nTRA-F127-instilled rats was found; however, the nTRA-F68/F127, nTRA-Car/F127, and nTRA-MC/F127 (combination-ISG) attenuated the vessel leakage, nitric oxide, and tumor necrosis factor-α expression. In particular, nTRA-F68/F127 was significant in preventing the conjunctival inflammation. In conclusion, we found that the combination-ISG base prolonged the residence time of Tra-NPs; however, Tra-NP release from the formulation was attenuated, and the T_max was delayed longer than that in nTRA. The balance of drug residence and diffusion in lacrimal fluid may be important in providing high ocular bioavailability in formulations containing solid nanoparticles.

Offspring born to influenza A virus infected pregnant mice have increased susceptibility to viral and bacterial infections in early life

Influenza during pregnancy can affect the health of offspring in later life, among which neurocognitive disorders are among the best described. Here, we investigate whether maternal influenza infection has adverse effects on immune responses in offspring. We establish a two-hit mouse model to study the effect of maternal influenza A virus infection (first hit) on vulnerability of offspring to heterologous infections (second hit) in later life. Offspring born to influenza A virus infected mothers are stunted in growth and more vulnerable to heterologous infections (influenza B virus and MRSA) than those born to PBS- or poly(I:C)-treated mothers. Enhanced vulnerability to infection in neonates is associated with reduced haematopoetic development and immune responses. In particular, alveolar macrophages of offspring exposed to maternal influenza have reduced capacity to clear second hit pathogens. This impaired pathogen clearance is partially reversed by adoptive transfer of alveolar macrophages from healthy offspring born to uninfected dams. These findings suggest that maternal influenza infection may impair immune ontogeny and increase susceptibility to early life infections of offspring.

Influenza infection during pregnancy can affect health of offspring but it is not clear how this affects immune responses. Here the authors use a mouse model to show that influenza infection during pregnancy can increase susceptibility to secondary infection and alter immune cell function in offspring.

Intergenerational cycle of disease: Maternal mastitis is associated with poorer daughter performance in dairy cattle

Adverse prenatal environments, such as maternal stress and infections, can influence the health and performance of offspring. Mastitis is the most common disease in dairy cattle, yet the intergenerational effects have not been specifically investigated. Therefore, we examined the associations between the dam's mammary gland health and daughter performance using somatic cell score (SCS) as a proxy for mammary health. Using data obtained from Dairy Records Management Systems (Raleigh, NC), we linked daughter records with their dam's records for the lactation in which the daughter was conceived. Linear and quadratic relationships of dam mean SCS with the daughter's age at first calving (AFC; n = 15,992 daughters, 4,366 herds), first- (n = 15,119 daughters, 4,213 herds) and second-lactation SCS (n = 3,570 daughters, 1,554 herds), first- and second-lactation mature-equivalent 305-d milk yield, and milk component yields were assessed using mixed linear regression models. We uncovered a phenomenon similar to those found in human and mouse models examining prenatal inflammation effects, whereby daughters born from dams with elevated SCS had poorer performance. Dam mean SCS was positively associated with daughter's AFC and first- and second-lactation mean SCS. Furthermore, for every 1-unit increase in dam mean SCS, daughter's first- and second-lactation mature-equivalent fat yield declined by 0.34% and 0.91% (-1.6 ± 0.49 kg, -4.0 ± 1.0 kg, respectively), although no effect was found on first- or second-lactation milk or milk protein yield. When accounting for genetics, daughter SCS, and AFC (first lactation only), dam mean SCS was associated with reduced second-lactation milk fat yield (-3.5 ± 1.8 kg/unit SCS), and a tendency was found for first-lactation milk fat yield (-1.9 ± 1.0 kg/unit SCS). Taken together, the association of greater dam mean SCS with lesser daughter milk fat yield is likely due to a few underlying mechanisms, in particular, a predisposition for mastitis and alterations in the epigenome controlling milk fat synthesis. As such, future studies should examine epigenetic mechanisms as a potential underpinning of this phenomenon.

Exposure to Maternal Immune Activation Causes Congenital Unfolded Protein Response Defects and Increases the Susceptibility to Postnatal Inflammatory Stimulation in Offspring

Background

A number of childhood diseases have been identified, such as severe infection or autoinflammatory disease, in which immune overreaction against inflammation is a possible underlying mechanism. Previous reports have demonstrated that fetal cells exposed to maternal immune activation (MIA) induced by polyriboinosinic-polyribocytidylic acid [poly(I:C)] exhibited hypersensitivity to inflammation in vitro. However, the details of this mechanism remain unclear. Therefore, this study aimed to reveal the reaction to inflammation in offspring exposed to MIA in the prenatal period, as well as its molecular mechanism, using a viral infection mouse model.

Materials and Methods

Pregnant mice at 12.5, 14.5, and 16.5 days post coitum were injected intraperitoneally with poly(I:C) 20 mg/kg body weight (BW) or saline. Offspring aged 3-4 weeks received the second injection of 20 mg/kg BW or 4 mg/kg BW poly(I:C) or saline. Serum and tissues were collected at 2, 24, 48, and 72 h after the postnatal injection. The cytokine profile, histopathology of organs, and unfolded protein response (UPR) in offspring were examined.

Results

The serum levels of interleukin (IL)-6, IL-17, and interferon-γ were significantly higher in the MIA group, and acute liver necrosis was detected. Moreover, failure in UPR was observed in the MIA group compared with that in the control group.

Conclusion

Overall, MIA exposure in utero caused failure in UPR as well as immune overreaction to the second attack of inflammation in offspring. Our results suggested that prenatal exposure to MIA might contribute to the congenital inflammatory constitution after birth.

In utero Exposure to Maternal Chronic Inflammation Transfers a Pro-Inflammatory Profile to Generation F2 via Sex-Specific Mechanisms

Generational transfer of maladaptations in offspring have been reported to persist for multiple generations in conditions of chronic inflammation, metabolic and psychological stress. Thus, the current study aimed to expand our understanding of the nature, potential sex specificity, and transgenerational plasticity of inflammatory maladaptations resulting from maternal chronic inflammation. Briefly, F1 and F2 generations of offspring from C57/BL/6 dams exposed to a modified maternal periconception systemic inflammation (MSPI) protocol were profiled in terms of leukocyte and splenocyte counts and cytokine responses, as well as glucocorticoid sensitivity. Overall, F1 male and female LPS groups presented with glucocorticoid hypersensitivity (with elevated corticosterone and increased leukocyte glucocorticoid receptor levels) along with a pro-inflammatory phenotype, which carried over to the F2 generation. The transfer of inflammatory and glucocorticoid responsiveness from F1 to F2 is evident, with heritability of this phenotype in F2. The findings suggest that maternal (F0) perinatal chronic inflammation resulted in glucocorticoid dysregulation and a resultant pro-inflammatory phenotype, which is transferred in the maternal lineage but seems to affect male offspring to a greater extent. Of further interest, upregulation of IL-1β cytokine responses is reported in female offspring only. The cumulative maladaptation reported in F2 offspring when both F1 parents were affected by maternal LPS exposure is suggestive of immune senescence. Given the potential impact of current results and the lack of sex-specific investigations, more research in this context is urgently required.

Symposium review: Late-gestation maternal factors affecting the health and development of dairy calves

Efficient production of heifers is fundamental to the productivity and sustainability of dairy farms. However, high preweaning morbidity and mortality rates are frequently reported worldwide, imposing substantial welfare and economic implications. A major contributing factor to disease susceptibility in the neonatal stage is the inability of calves to mount an effective immune response. Appreciation is now greater that exposure in utero to several stresses (nutritional, social, metabolic, and so on) during the last stages of pregnancy have downstream carryover effects in calves' health, growth, and development. Suboptimal intrauterine conditions during critical periods of development lead to changes in tissue structure and function that may have long-term consequences on the offspring's physiology and disease susceptibility. Indeed, preweaning metabolic function and growth are associated with future milk production. Thus, late-gestation carryover effects span into the lactating stage of the heifers. Nevertheless, researchers have been studying how to minimize these effects. This review will discuss the effects of maternal stress during late gestation on the offspring's growth, productivity, metabolism, and health. In addition, strategies focusing on maternal interventions that improve neonatal health will be discussed. A better understanding of the intrauterine conditions affecting calf health and growth may facilitate the design of management practices that could improve neonatal development and future cow productivity.

Prenatal and childhood exposures are associated with thymulin concentrations in young adolescent children in rural Nepal

The thymus undergoes a critical period of growth and development early in gestation and, by mid-gestation, immature thymocytes are subject to positive and negative selection. Exposure to undernutrition during these periods may permanently affect phenotype. We measured thymulin concentrations, as a proxy for thymic size and function, in children (n = 290; aged 9-13 years) born to participants in a cluster-randomized trial of maternal vitamin A or β-carotene supplementation in rural Nepal (1994-1997). The geometric mean (95% confidence interval) thymulin concentration was 1.37 ng/ml (1.27, 1.47). A multivariate model of early-life exposures revealed a positive association with gestational age at delivery (β = 0.02; P = 0.05) and higher concentrations among children born to β-carotene-supplemented mothers (β = 0.19; P < 0.05). At ∼9-12 years of age, thymulin was positively associated with all anthropometric measures, with height retained in our multivariate model (β = 0.02; P < 0.001). There was significant seasonal variation: concentrations tended to be lower pre-monsoon (β = -0.13; P = 0.15), during the monsoon (β = -0.22; P = 0.04), and pre-harvest (β = -0.34; P = 0.01), relative to the post-harvest season. All early-life associations, except supplementation, were mediated in part by nutritional status at follow-up. Our findings underscore the known sensitivity of the thymus to nutrition, including potentially lasting effects of early nutritional exposures. The relevance of these findings to later disease risk remains to be explored, particularly given the role of thymulin in the neuroendocrine regulation of inflammation.

Partner social support during pregnancy and the postpartum period and inflammation in 3-month-old infants

Prenatal social stress "programs" offspring immune activity in animal models, but how the prenatal social environment affects human offspring inflammation is not known. Here, we test associations between prenatal partner support quality, i.e. positive/helpful support, negative/upsetting support, and their interaction, and infant inflammatory markers. A sample of 113 women from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort were followed from early pregnancy to 3-months postpartum. Partner support quality was measured during pregnancy and the postpartum period. Three-month-old infant blood samples were assayed for inflammatory markers, i.e., adaptive immune markers IFNγ, IL12p70 and IL10. The prenatal positive-by-negative partner support interaction predicted infant IFNγ, IL12p70, and IL10, p's<.035, independent of covariates and postpartum partner support. When negative partner support was high, high positive support predicted higher infant IFNγ, IL12p70, and IL10. As such, partner support during pregnancy that is both highly negative/upsetting and also highly positive/helpful predicted adaptive immunity markers in infants at 3 months of age.

Prenatal inflammation and risk for schizophrenia: A role for immune proteins in neurodevelopment

Prenatal inflammation is an established risk factor for schizophrenia. However, the specific inflammatory pathways that mediate this association remain unclear. Potential candidate systems include inflammatory markers produced by microglia, such as cytokines and complement. Accumulating evidence suggests that these markers play a role in typical neurodevelopmental processes, such as synapse formation and interneuron migration. Rodent models demonstrate that altered marker levels during the prenatal period can cause lasting deficits in these systems, leading to cognitive deficits that resemble schizophrenia. This review assesses the potential role of prenatal cytokine and complement elevations on the etiology of schizophrenia. The current neurobiological understanding of the development of schizophrenia is reviewed to identify candidate cellular mechanisms that may be influenced by prenatal inflammation. We discuss the functions that cytokines and complement may play in prenatal neurodevelopment, review evidence that links exposure to these factors with risk for schizophrenia, and consider how these markers may interact with genetic vulnerabilities to influence the neurodevelopment of schizophrenia. We consider how prenatal inflammatory exposure may influence childhood and adolescent developmental risk trajectories for schizophrenia. Finally, we identify areas of further research needed to support the development of anti-inflammatory treatments to prevent the development of schizophrenia in at-risk neonates.

Maternal late-gestation metabolic stress is associated with changes in immune and metabolic responses of dairy calves

Metabolic stress in periparturient dairy cows is characterized by excessive lipid mobilization, inflammation, and oxidative stress that is associated with immune dysfunction. Thus, metabolic stress around the time calving is linked to the development of various early-lactation health disorders. Maternal status during late pregnancy can have carryover effects on several health and production variables of neonatal calves. However, the effects of metabolic stress during gestation on metabolic and immune responses of newborn calves remain unknown. Thus, we aimed to investigate whether metabolic stress in late-gestation dairy cows is associated with changes in the metabolic and immune responses of their offspring during the first month of life. Holstein-Friesian cows (n = 12) were blood sampled at 28 and 15 d before expected calving. The average between these 2 sampling points in the serum concentrations of nonesterified fatty acids (NEFA), haptoglobin (Hp), and oxidant status index (OSi)-defined as the ratio between reactive oxygen and nitrogen species and total antioxidant potential-were calculated as indicators of the degree of lipid mobilization, inflammation, and oxidant status (OS), respectively. Calves were subsequently divided into groups (n = 6 each) according to their dams' high or low degree of lipid mobilization, inflammation, and OS. The metabolic responses of calves in each of these groups were compared weekly throughout their first month of life by assessing serum concentration of NEFA, Hp, and OSi. Additionally, whole blood was obtained from calves at each sampling period and subjected to a lipopolysaccharide (LPS)-stimulated tumor necrosis factor-α (TNF-α) production assay to assess cell-mediated innate immunity against induced inflammatory responses, using high (5 μg/mL of blood) and low (10 ng/mL) concentrations of LPS. Calves born to cows with higher NEFA or OSi showed lower body weight at birth and throughout the study, whereas no association between any of the maternal groups and average daily gain at 4 wk of age was identified. Serum concentrations of reactive oxygen and nitrogen species were higher in calves exposed to higher maternal NEFA concentrations or OSi when compared with calves born to cows with lower values of these biomarkers. Calves exposed to high maternal OS also had higher circulating concentrations of Hp and TNF-α, indicating greater basal inflammatory responses when compared with calves born to cows with a lower OSi. In contrast, LPS-induced inflammatory responses were less robust in calves exposed to higher maternal biomarkers of inflammation or OS, suggesting compromised immune responses to microbial agonists. Collectively, these data suggest that prenatal exposure to maternal parameters of metabolic stress may adversely affect some metabolic and inflammatory responses of the offspring that could influence disease susceptibility.

Maternal immune activation in neurodevelopmental disorders

Converging lines of evidence from basic science and clinical studies suggest a relationship between maternal immune activation (MIA) and neurodevelopmental disorders such as autism spectrum disorder (ASD) and schizophrenia. The mechanisms through which MIA increases the risk of neurodevelopmental disorders have become a subject of intensive research. This review aims to describe how dysregulation of microglial function and immune mechanisms may link MIA and neurodevelopmental pathologies. We also summarize the current evidence in animal models of MIA. Developmental Dynamics 247:588-619, 2018. © 2017 Wiley Periodicals, Inc.

Neonatal lipopolysaccharide exposure does not diminish the innate immune response to a subsequent lipopolysaccharide challenge in Holstein bull calves

The innate immune response following experimental mastitis is quite variable between individual dairy cattle. An inflammatory response that minimizes collateral damage to the mammary gland while still effectively resolving the infection following pathogen exposure is beneficial to dairy producers. The ability of a lipopolysaccharide (LPS) exposure in early life to generate a low-responding phenotype and thus reduce the inflammatory response to a later-life LPS challenge was investigated in neonatal bull calves. Ten Holstein bull calves were randomly assigned to either an early life LPS (ELL) group (n=5) or an early life saline (ELS) group (n=5). At 7d of age, calves received either LPS or saline, and at 32d of age, all calves were challenged with an intravenous dose of LPS to determine the effect of the early life treatment (LPS or saline) on the immune response generated toward a subsequent LPS challenge. Dermal fibroblast and monocyte-derived macrophage cultures from each calf were established at age 20 and 27d, respectively, to model sustained effects from the early life LPS exposure on gene expression and protein production of components within the LPS response pathway. The ELL calves had greater levels of plasma IL-6 and tumor necrosis factor-α than the ELS calves following the early life LPS or saline treatments. However, levels of these 2 immune markers were similar between ELL and ELS calves when both groups were subsequently challenged with LPS. A comparison of the in vitro LPS responses of the ELL and ELS calves revealed similar patterns of protein production and gene expression following an LPS challenge of both dermal fibroblast and monocyte-derived macrophage cultures established from the treatment groups. Whereas an early life exposure to LPS did not result in a dampened inflammatory response toward a later LPS challenge in these neonatal bull calves, the potential that exposure to inflammation or stress in early life or in utero can create an offspring with a low-responding phenotype as an adult is intriguing and has been documented in rodents. Further work is needed to determine if an inflammatory exposure in utero in a dairy animal would result in a low-responding innate immune phenotype.

The poly(I:C)-induced maternal immune activation model in preclinical neuropsychiatric drug discovery

Increasing epidemiological and experimental evidence implicates gestational infections as one important factor involved in the pathogenesis of several neuropsychiatric disorders. Corresponding preclinical model systems based upon maternal immune activation (MIA) by treatment of the pregnant female have been developed. These MIA animal model systems have been successfully used in basic and translational research approaches, contributing to the investigation of the underlying pathophysiological mechanisms at the molecular, cellular and behavioral levels. The present article focuses on the application of a specific MIA rodent paradigm, based upon treatment of the gestating dam with the viral mimic polyinosinic-polycytidilic acid (Poly(I:C)), a synthetic analog of double-stranded RNA (dsRNA) which activates the Toll-like receptor 3 (TLR3) pathway. Important advantages and constraints of this animal model will be discussed, specifically in light of gestational infection as one vulnerability factor contributing to the complex etiology of mood and psychotic disorders, which are likely the result of intricate multi-level gene×environment interactions. Improving our currently incomplete understanding of the molecular pathomechanistic principles underlying these disorders is a prerequisite for the development of alternative therapeutic approaches which are critically needed in light of the important drawbacks and limitations of currently available pharmacological treatment options regarding efficacy and side effects. The particular relevance of the Poly(I:C) MIA model for the discovery of novel drug targets for symptomatic and preventive therapeutic strategies in mood and psychotic disorders is highlighted in this review article.

Region Specific Effects of Maternal Immune Activation on Offspring Neuroimmune Function

Growing evidence suggests that maternal immune activation has a significant impact on the immuno-competence of the offspring. The present study aimed to characterize region-specific effects of maternal immune activation on the offspring’s neuroimmune function. The offspring born to dams treated with saline or lipopolysaccharide (LPS) at gestational day 18 was stimulated with saline or LPS at postnatal day 21, and the mRNA expression of various inflammatory genes in different brain regions of the offspring was analyzed. The offspring born to saline-treated dams exhibited a typical neuroimmune response with elevated levels of cytokines and chemokines following LPS stimulation in all four brain regions examined. In contrast, the offspring born to LPS-treated dams exhibited significantly reduced mRNA induction of cytokines and chemokines following LPS stimulation in the prefrontal cortex but not in the brainstem when compared with pups born to saline-treated dams. Furthermore, the mRNA expression of LPS-induced I-κBζ was significantly attenuated in the prefrontal cortex when compared with pups born to saline-treated dams. These results suggest that maternal LPS may have differential effects on the neuroimmune function in different regions of the offspring brain, and highlight the importance of maternal milieu in the development of neuroimmune function in the offspring.

Effects of pregnancy on obesity-induced inflammation in a mouse model of fetal programming

OBJECTIVE

Maternal obesity is associated with increased risk of metabolic dysfunction in the offspring. It is not clear whether it is the metabolic changes or chronic low-grade inflammation in the obese state that causes this metabolic programming. We therefore investigated whether low-grade inflammation was present in obese dams compared with controls dams at gestation day 18 (GD18).

METHODS

Female mice were fed either a standard chow diet or a highly palatable obesogenic diet for 6 weeks before conception. Mice were either kileed before mating (n=12 in each group) or on GD18 (n=8 in each group). Blood and tissues were collected for analysis.

RESULTS

The obesogenic diet increased body weight and decreased insulin sensitivity before conception, while there was no difference between the groups at GD18. Local inflammation was assayed by macrophage count in adipose tissue (AT) and liver. Macrophage count in the AT was increased significantly by the obesogenic diet, and the hepatic count also showed a tendency to increased macrophage infiltration before gestation. This was further supported by a decreased population of monocytes in the blood of the obese animals, which suggested that monocytes are being recruited from the blood to the liver and AT in the obese animals. Gestation reversed macrophage infiltration, such that obese dams showed a lower AT macrophage count at the end of gestation compared with pre-pregnancy obese mice, and there were no longer a tendency toward increased hepatic macrophage count. Placental macrophage count was also similar in the two groups.

CONCLUSION

At GD18, obese dams were found to have similar macrophage infiltration in placenta, AT and liver as lean dams, despite an incipient infiltration before gestation. Thus, the obesity-induced inflammation was reversed during gestation.

Altered nociceptive, endocrine, and dorsal horn neuron responses in rats following a neonatal immune challenge

The neonatal period is characterized by significant plasticity where the immune, endocrine, and nociceptive systems undergo fine-tuning and maturation. Painful experiences during this period can result in long-term alterations in the neurocircuitry underlying nociception, including increased sensitivity to mechanical or thermal stimuli. Less is known about the impact of neonatal exposure to mild inflammatory stimuli, such as lipopolysaccharide (LPS), on subsequent inflammatory pain responses. Here we examine the impact of neonatal LPS exposure on inflammatory pain sensitivity and HPA axis activity during the first three postnatal weeks. Wistar rats were injected with LPS (0.05mg/kg IP, Salmonella enteritidis) or saline on postnatal days (PNDs) 3 and 5 and later subjected to the formalin test at PNDs 7, 13, and 22. One hour after formalin injection, blood was collected to assess corticosterone responses. Transverse spinal cord slices were also prepared for whole-cell patch clamp recording from lumbar superficial dorsal horn neurons (SDH). Brains were obtained at PND 22 and the hypothalamus was isolated to measure glucocorticoid (GR) and mineralocorticoid receptor (MR) transcript expression using qRT-PCR. Behavioural analyses indicate that at PND 7, no significant differences were observed between saline- or LPS-challenged rats. At PND 13, LPS-challenged rats exhibited enhanced licking (p<.01), and at PND 22, increased flinching in response to formalin injection (p<.05). LPS-challenged rats also displayed increased plasma corticosterone at PND 7 and PND 22 (p<.001) but not at PND 13 following formalin administration. Furthermore, at PND 22 neonatal LPS exposure induced decreased levels of GR mRNA and increased levels of MR mRNA in the hypothalamus. The intrinsic properties of SDH neurons were similar at PND 7 and PND 13. However, at PND 22, ipsilateral SDH neurons in LPS-challenged rats had a lower input resistance compared to their saline-challenged counterparts (p<.05). These data suggest neonatal LPS exposure produces developmentally regulated changes in formalin-induced behavioural responses, corticosterone levels, and dorsal horn neuron properties following noxious stimulation later in life. These findings highlight the importance of immune activation during the neonatal period in shaping pain sensitivity later in life. This programming involves both spinal cord neurons and the HPA axis.

CD4⁺ but not CD8⁺ T cells revert the impaired emotional behavior of immunocompromised RAG-1-deficient mice

An imbalanced immune system has long been known to influence a variety of mood disorders including anxiety, obsessive-compulsive disorders and depression. In this study, we sought to model the impact of an immunocompromised state on these emotional behaviors using RAG-1⁻/⁻ mice, which lack T and B cells. We also investigated the relative contribution of CD4⁺ or CD8⁺ T cells to these manifestations using RAG-1⁻/⁻/OT-II and RAG-1⁻/⁻/OT-I transgenic mice, respectively. Our results show that RAG-1⁻/⁻ mice present a significant increase in digging and marble-burying activities compared with wild-type mice. Surprisingly, these anxiety-like behaviors were significantly reverted in RAG-1⁻/⁻/OT-II but not RAG-1⁻/⁻/OT-I transgenic mice. Immunodepletion experiments with anti-CD4 or anti-CD8 in C57/BL6 mice or repopulation studies in RAG-1⁻/⁻ mice did not reproduce these findings. Microarray analysis of the brain of RAG-1⁻/⁻ and RAG-1⁻/⁻/OT-II mice revealed a significantly different gene fingerprint, with the latter being more similar to wild-type mice than the former. Further analysis revealed nine main signaling pathways as being significantly modulated in RAG-1⁻/⁻ compared with wild-type mice. Taken together, these results suggest that life-long rather than transient immunodeficient conditions influence the emotional behaviors in mice. Most interestingly, these effects seem to correlate with a specific absence of CD4⁺ rather than CD8⁺ T cells. Validation of these findings in man might provide new clues on the mechanism by which early life immune modulation might impact mood response in adults and provide a further link between immune and emotional well-being.

Long-lasting impact of early life immune stress on neuroimmune functions

Fever is one major cardinal sign of disease. It results from an intricate interplay between the immune system and the central nervous system. Bacterial or viral infections activate peripheral immune competent organs which send inflammatory signals to the brain and lead to an increase in body temperature. The increased body temperature creates a conducive environment to optimize the body's fight against the infection. A large body of experimental evidence suggests that early life bacterial or viral infections can lead to a long-lasting impact on this natural febrile response. The early life pathogenic encounter heightens the hypothalamic-pituitary-adrenal axis response, dampens the innate immune system, and consequently reduces the febrile response to a subsequent immune challenge during adulthood. This 'programming' effect operates only when such early life immune challenges occur during a critical window of either prenatal or postnatal development. In this review, the mechanisms underlying the long-lasting impact of perinatal immune challenge on adult fever are addressed.

Sex effects on neurodevelopmental outcomes of innate immune activation during prenatal and neonatal life

Humans are exposed to potentially harmful agents (bacteria, viruses, toxins) throughout our lifespan; the consequences of such exposure can alter central nervous system development. Exposure to immunogens during pregnancy increases the risk of developing neurological disorders such as schizophrenia and autism. Further, sex hormones, such as estrogen, have strong modulatory effects on immune function and have also been implicated in the development of neuropathologies (e.g., schizophrenia and depression). Similarly, animal studies have demonstrated that immunogen exposure in utero or during the neonatal period, at a time when the brain is undergoing maturation, can induce changes in learning and memory, as well as dopamine-mediated behaviors in a sex-specific manner. Literature that covers the effects of immunogens on innate immune activation and ultimately the development of the adult brain and behavior is riddled with contradictory findings, and the addition of sex as a factor only adds to the complexity. This review provides evidence that innate immune activation during critical periods of development may have effects on the adult brain in a sex-specific manner. Issues regarding sex bias in research as well as variability in animal models of immune function are discussed.

Prenatal programming of the innate immune response following in utero exposure to inflammation: a sexually dimorphic process?

Maternal infection and inflammation are common events during pregnancy. This article documents evidence that suggests such inflammation compromises the development of the fetal innate immune response, in support of an in utero origins hypothesis of neonatal and childhood inflammatory disease. The potential for this response to exhibit sex specificity is also explored, based on evidence of sexually dimorphic placental responses to maternal inflammation.

Maternal inhalation of surface-coated nanosized titanium dioxide (UV-Titan) in C57BL/6 mice: effects in prenatally exposed offspring on hepatic DNA damage and gene expression

We investigated effects of maternal pulmonary exposure to titanium dioxide (UV-Titan) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were inhalation exposed (1 h/day to 42 mg UV-Titan/m(3) aerosolised powder or filtered air) during gestation days (GDs) 8-18. We evaluated DNA strand breaks using the comet assay in bronchoalveolar lavage (BAL) cells and livers of the time-mated mice (5 and 26-27 days after inhalation exposure), and in livers of the offspring (post-natal days (PND) 2 and 22). We also analysed hepatic gene expression in newborns using DNA microarrays. UV-Titan exposure did not induce DNA strand breaks in time-mated mice or their offspring. Transcriptional profiling of newborn livers revealed changes in the gene expression related to the retinoic acid signalling pathway in the females, while gene expression in male offspring was unaffected. Changes may be a secondary response to maternal inflammation although no direct link was evident through gene expression analysis.

Exposure of pregnant mice to carbon black by intratracheal instillation: toxicogenomic effects in dams and offspring

Exposure to nanomaterials (NM) during sensitive developmental stages may predispose organisms to diseases later in life. However, direct translocation of NM from mother to fetus through the placenta is limited. The present study tests the hypothesis that pulmonary exposure to NM and NM-induced response, such as inflammation during gestation, leads to secondary effects in the fetus. Time-mated C57BL/6BomTac mice were exposed by intratracheal instillation to vehicle (Nanopure water) or one of three concentrations (2.75, 13.5 or 67 μg in 40 μl Nanopure water) of carbon black Printex 90 (CB) on gestational days 7, 10, 15 and 18, to final cumulative doses of 11, 54 or 268 μg/animal. Samples from a subset of male and female newborns were collected on postnatal day 2 (4 days after the last maternal exposure) and from dams 26 to 27 days post-exposure (post-weaning period). Histopathology, DNA microarrays, pathway-specific RT-PCR arrays, focussed RT-PCR, and tissue protein analysis were employed to characterize pulmonary response in dams exposed to CB during pregnancy. Hepatic gene expression in newborns was interpreted in light of the observed biological responses and gene expression changes arising in the lungs of dams following CB exposure. Although retention of CB particles was observed in dams from both the medium and the high dose groups, neutrophil-marked inflammation and altered expression of several cytokines and chemokines, both at the transcriptional and tissue protein levels, was significant only in the high dose group. Analysis of newborn livers by DNA microarrays revealed that female offspring were more sensitive to maternal exposure than male offspring. Cellular signalling, inflammation, cell cycle and lipid metabolism were among the biological pathways affected in female offspring. Males, however, responded with subtle changes in metabolism-related genes. Further investigation is required to determine the long-term health consequences of the gene expression changes in offspring and response to environmental stresses.

Nutritionally mediated programming of the developing immune system

A growing body of evidence highlights the importance of a mother's nutrition from preconception through lactation in programming the emerging organ systems and homeostatic pathways of her offspring. The developing immune system may be particularly vulnerable. Indeed, examples of nutrition-mediated immune programming can be found in the literature on intra-uterine growth retardation, maternal micronutrient deficiencies, and infant feeding. Current models of immune ontogeny depict a "layered" expansion of increasingly complex defenses, which may be permanently altered by maternal malnutrition. One programming mechanism involves activation of the maternal hypothalamic-pituitary-adrenal axis in response to nutritional stress. Fetal or neonatal exposure to elevated stress hormones is linked in animal studies to permanent changes in neuroendocrine-immune interactions, with diverse manifestations such as an attenuated inflammatory response or reduced resistance to tumor colonization. Maternal malnutrition may also have a direct influence, as evidenced by nutrient-driven epigenetic changes to developing T regulatory cells and subsequent risk of allergy or asthma. A 3rd programming pathway involves placental or breast milk transfer of maternal immune factors with immunomodulatory functions (e.g. cytokines). Maternal malnutrition can directly affect transfer mechanisms or influence the quality or quantity of transferred factors. The public health implications of nutrition-mediated immune programming are of particular importance in the developing world, where prevalent maternal undernutrition is coupled with persistent infectious challenges. However, early alterations to the immune system, resulting from either nutritional deficiencies or excesses, have broad relevance for immune-mediated diseases, such as asthma, and chronic inflammatory conditions like cardiovascular disease.

Neonatal respiratory infection and adult re-infection: effect on glucocorticoid and mineralocorticoid receptors in the hippocampus in BALB/c mice

Stressful events during the perinatal period in both humans and animals have long-term consequences for the development and function of physiological systems and susceptibility to disease in adulthood. One form of stress commonly experienced in the neonatal period is exposure to bacterial and viral infections. The current study investigated the effects of live Chlamydia muridarum bacterial infection at birth followed by re-infection in adulthood on hippocampal glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) and stress response outcomes. Within 24 h of birth, neonatal mice were infected intranasally with C. muridarum (400 inclusion-forming units [ifu]) or vehicle. At 42 days, mice were re-infected (100 ifu) and euthanized 10 days later. In males, infection in adulthood alone had the most impact on the parameters measured with significant increases in GR protein compared to adult infection alone; and significant increases MR protein and circulating corticosterone compared to other treatment groups. Neonatal infection alone induced the largest alterations in the females with results showing reciprocal patterns for GR protein and TH protein. Perinatal infection resulted in a blunted response following adult infection for both males and females across all parameters. The present study demonstrates for the first time that males and females respond differently to infection based on the timing of the initial insult and that there is considerable sex differences in the hippocampal phenotypes that emerge in adulthood after neonatal infection.

Mouse maternal systemic inflammation at the zygote stage causes blunted cytokine responsiveness in lipopolysaccharide-challenged adult offspring

Background

The preimplantation embryo is sensitive to culture conditions in vitro and poor maternal diet in vivo. Such environmental perturbations can have long-lasting detrimental consequences for offspring health and physiology. However, early embryo susceptibility to other aspects of maternal health and their potential long-term influence into adulthood is relatively unexplored. In this study, we established an in vivo mouse model of maternal periconceptional systemic inflammation by intraperitoneal lipopolysaccharide (LPS) administration on the day of zygote formation and investigated the consequences into adulthood.

Results

In the short term, maternal LPS challenge induced a transient and typical maternal sickness response (elevated serum proinflammatory cytokines and hypoactive behaviour). Maternal LPS challenge altered preimplantation embryo morphogenesis and cell lineage allocation, resulting in reduced blastocyst inner cell mass (ICM) cell number and a reduced ICM:trophectoderm cell ratio. In the long term, diverse aspects of offspring physiology were affected by maternal LPS treatment. Whilst birthweight, growth and adult blood pressure were unaltered, reduced activity in an open-field behaviour test, increased fat pad:body weight ratio and increased body mass index were observed in male, but not female, offspring. Most importantly, the maternal LPS challenge caused corticosterone-independent blunting of the serum proinflammatory cytokine response to innate immune challenge in both male and female offspring. The suppressed state of innate immunity in challenged offspring was dose-dependent with respect to the maternal LPS concentration administered.

Conclusions

These results demonstrate for the first time that the preimplantation embryo in vivo is sensitive to maternal systemic inflammation, with effects on blastocyst cell lineage allocation and consequences for behaviour, adiposity and innate immune response in adult offspring. Critically, we identify a novel mechanism mediated through maternal-embryonic interactions that confers plasticity in the development of the innate immune system, which is potentially important in setting postnatal tolerance to environmental pathogens. Our study extends the concept of developmental programming of health and disease to include maternal health at the time of conception.

Lipopolysaccharide induced protection against sulfur mustard cytotoxicity in RAW264.7 cells through generation of TNF-alpha

Sulfur mustard (HD), a very potent alkylating agent and lipopolysacchride (LPS), are both well characterized inflammatory factors. We have found that concomitant exposure of murine macrophage cells (RAW264.7) to LPS and HD induced protection against HD induced cytotoxicity. Both HD and LPS induce release of inflammatory markers in RAW264.7 cells. However, there are marked differences in the repertoire of inflammatory factors released by the two toxins: While exposure to HD, induced a dose-dependant death of these cells, no significant change in survival rate was observed following LPS (1-100 ng/ml) exposure. Additionally, LPS elicited a robust nitric oxide (NO) and TNF-alpha secretion whereas HD was practically ineffective. Both toxins increased PGE(2) secretion in a concentration dependent manner. Treatment of HD-exposed RAW264.7 cells with anti-inflammatory drugs such as dexamethazone (5 muM), voltaren (diclofenac) (8 muM) or doxycycline (5 muM), decreased the release of cytokines but had no effect on cell viability. Simultaneous application of LPS (100 ng/ml) and HD (20-100 muM) resulted in an amelioration of HD cytotoxicity. Adding the NO generator S-nitrosoglutathione (GSNO) or inhibiting NO production using L-N(G)-monomethyl Arginine, had no effect on cell viability. Moreover, addition of PGE(2) (20 ng/ml) failed to induce any changes in cell viability under basal or HD-induced toxicity. In contrast, TNF-alpha (20 ng/ml) provided remarkable protection against HD-induced cell death. These findings strongly suggest that LPS exerts its protective action against HD toxicity through the generation of TNF-alpha and may provide better understanding of the mechanism of cytoprotection.

Endotoxin exposure during late pregnancy alters ovine offspring febrile and hypothalamic-pituitary-adrenal axis responsiveness later in life

A growing number of studies indicate that maternal infection during pregnancy is associated with adverse fetal development and neonatal health. In this study, late gestating sheep (day 135) were challenged systemically with saline (0.9%) or Escherichia coli lipopolysaccharide endotoxin (400 ng/kg x 3 consecutive days, or 1.2 microg/kg x 1 day) in order to assess the impact of maternal endotoxemia on the developing fetal neuroendocrine-immune system. During adulthood, cortisol secretion and febrile responses of female offspring and the cortisol response of the male offspring to endotoxin (400 ng/kg), as well as the female cortisol response to adrenocorticotropic hormone (ACTH) challenge, were measured to assess neuroendocrine-immune function. These studies revealed that maternal endotoxin treatment during late gestation altered the female febrile and male and female cortisol response to endotoxin exposure later in life; however, the response was dependent on the endotoxin treatment regime that the pregnant sheep received. The follow-up ACTH challenge suggests that programing of the adrenal gland may be altered in the female fetus during maternal endotoxemia. The long-term health implications of these changes warrant further investigation.

Maternal influenza infection during pregnancy impacts postnatal brain development in the rhesus monkey

BACKGROUND

Maternal infection with influenza and other pathogens during pregnancy has been associated with increased risk for schizophrenia and neurodevelopmental disorders. In rodent studies, maternal inflammatory responses to influenza affect fetal brain development. However, to verify the relevance of these findings to humans, research is needed in a primate species with more advanced prenatal corticogenesis.

METHODS

Twelve pregnant rhesus monkeys were infected with influenza, A/Sydney/5/97 (H3N2), 1 month before term (early third trimester) and compared with 7 control pregnancies. Nasal swabs and blood samples confirmed viral shedding and immune activation. Structural magnetic resonance imaging was conducted at 1 year; behavioral development and cortisol reactivity were also assessed.

RESULTS

Maternal infections were mild and self-limiting. At birth, maternally derived influenza-specific immunoglobulin G was present in the neonate, but there was no evidence of direct viral exposure. Birth weight and gestation length were not affected, nor were infant neuromotor, behavioral, and endocrine responses. However, magnetic resonance imaging analyses revealed significant reductions in cortical gray matter in flu-exposed animals. Regional analyses indicated the largest gray matter reductions occurred bilaterally in cingulate and parietal areas; white matter was also reduced significantly in the parietal lobe.

CONCLUSIONS

Influenza infection during pregnancy affects neural development in the monkey, reducing gray matter throughout most of the cortex and decreasing white matter in parietal cortex. These brain alterations are likely to be permanent, given that they were still present at the monkey-equivalent of older childhood and thus might increase the likelihood of later behavioral pathology.

Prenatal endotoxin exposure alters behavioural pain responses to lipopolysaccharide in adult offspring

Evidence suggests that exposure to bacterial endotoxin in early life can alter the production of pro-inflammatory cytokines in later life. This phenomenon may have significant consequences for pain and pain related behaviours as pro-inflammatory cytokines heighten pain sensitivity. This association has yet to be examined. As such, the aim of the present study was to characterize pain behaviours in adult rat offspring following prenatal endotoxin (PE) exposure. Pregnant F344 rats received endotoxin (200microg/kg, s.c.) or saline on gestational days 16, 18 and 20. Pain thresholds were assessed in the adult PE offspring (n=23) and control offspring (n=24) prior to and 4h following administration of lipopolysaccharide (LPS; 100microg/kg, s.c.). Three assays of pain were employed - the hot plate, tail immersion and von Frey tests. Results demonstrated sex-specific effects of prenatal endotoxin on the offspring, with PE males displaying unaltered pain thresholds on the von Frey test post-LPS administration (p<0.01), while male control offspring (n=24) displayed the expected hyperalgesia. Male PE offspring also displayed increased pain thresholds on the tail immersion test (p<0.01), while no change in pain sensitivity was observed in control males following LPS exposure. No difference in response was observed between the female PE and control offspring on the von Frey test, however PE female offspring displayed increased thresholds on the tail immersion test compared to baseline - an effect not observed in the control female offspring. Pain sensitivity on the hot plate test was unaffected by prenatal exposure to endotoxin. These data suggest that prenatal exposure to products associated with bacterial infection have the capacity to alter pain responses, which are evident in the adult offspring.

Postnatal programming of the innate immune response

A host's defensive response to a pathogen is a phylogenetically ancient reaction that consists of a CNS-mediated series of autonomic, hormonal and behavioral responses that combine to combat infection. The absence of such defense results in greater morbidity and mortality and thus, these responses are essential for survival. The postnatal period represents a malleable phase in which the long-term behavior and physiology of the developing organism, including its immune responses, can be influenced. Postnatal challenge of the immune system by introduction of live replicating infections, or administration of bacterial and viral mimetics, can result in a multidomain alteration to the defenses of the adult host. Findings from our laboratory and others' indicate that the postnatal administration of lipopolysaccharide (LPS) or polyinosinic:polycytidylic acid (PolyI:C), which mimic bacterial and viral infections respectively, can influence the neuroimmune response (generation of fever and production of cytokines) to a second challenge to the immune system in adulthood. This long-lasting alteration in the innate immune response is associated with myriad other effects on the animal's physiology and appears to be primarily mediated by a sensitized hypothalamic-pituitary-adrenal axis. Thus, a transient immunological perturbation to a developing animal may program the organism for subsequent health complications as an adult. In this review we discuss some of the potential mechanisms for these phenomena.

Altered hepatic inflammatory response in the offspring following prenatal LPS exposure

There is increasing evidence that maternal immune activation has a significant impact on the offspring's immune function. In this study, we examined the effects of maternal immune activation on the offspring's hepatic inflammatory response. We treated pregnant rats with 500 microg/kg LPS or saline on day 18 of pregnancy, subsequently stimulated the offspring with 250 microg/kg LPS or saline at postnatal day (P) 21, and then examined the expression of LPS cell surface receptors, namely toll-like receptor (TLR)-4 and CD14, and cytokines, namely tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and IL-6, as well as the activation of key intracellular mediators of the TLR-4 signaling cascade, namely p38 MAPK and p42/44 MAPK, in the offspring liver. We found that LPS-induced mRNA expression of IL-6 in the pups born to LPS-treated dams was significantly diminished compared with that in the pups born to saline-treated dams. Furthermore, maternal immune activation attenuated LPS-induced phosphorylation of p42/44 MAPK compared with the control pups without significantly affecting the phosphorylation of p38 MAPK. The correlation between the level of IL-6 expression and that of phosphorylated p42/44 MAPK suggests that p42/44 MAPK may play an important role in regulating hepatic IL-6 expression. Our results also suggest that maternal immune activation could have differential effects on various inflammatory mediators in the liver of the offspring.

Potential for early-life immune insult including developmental immunotoxicity in autism and autism spectrum disorders: focus on critical windows of immune vulnerability

Early-life immune insults (ELII) including xenobiotic-induced developmental immunotoxicity (DIT) are important factors in childhood and adult chronic diseases. However, prenatal and perinatal environmentally induced immune alterations have yet to be considered in depth in the context of autism and autism spectrum disorders (ASDs). Numerous factors produce early-life-induced immune dysfunction in offspring, including exposure to xenobiotics, maternal infections, and other prenatal-neonatal stressors. Early life sensitivity to ELII, including DIT, results from the heightened vulnerability of the developing immune system to disruption and the serious nature of the adverse outcomes arising after disruption of one-time immune maturational events. The resulting health risks extend beyond infectious diseases, cancer, allergy, and autoimmunity to include pathologies of the neurological, reproductive, and endocrine systems. Because these changes may include misregulation of resident inflammatory myelomonocytic cells in tissues such as the brain, they are a potential concern in cases of prenatal-neonatal brain pathologies and neurobehavioral deficits. Autism and ASDs are chronic developmental neurobehavioral disorders that are on the rise in the United States with prenatal and perinatal environmental factors suspected as contributors to this increase. Evidence for an association between environmentally associated childhood immune dysfunction and ASDs suggests that ELII and DIT may contribute to these conditions. However, it is not known if this linkage is directly associated with the brain pathologies or represents a separate (or secondary) outcome. This review considers the known features of ELII and DIT and how they may provide important clues to prenatal brain inflammation and the risk of autism and ASDs.

Possible role for early-life immune insult including developmental immunotoxicity in chronic fatigue syndrome (CFS) or myalgic encephalomyelitis (ME)

Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME) in some countries, is a debilitating disease with a constellation of multi-system dysfunctions primarily involving the neurological, endocrine and immune systems. While substantial information is available concerning the complex dysfunction-associated symptoms of CFS, environmental origins of the disease have yet to be determined. Part of the dilemma in identifying the cause(s) has been the focus on biomarkers (hormones, neurotransmitters, cytokines, infectious agents) that are contemporary with later-life CFS episodes. Yet, recent investigations on the origins of environmental diseases of the neurological, endocrine, reproductive, respiratory and immune systems suggest that early life toxicologic and other insults are pivotal in producing later-life onset of symptoms. As with autism and childhood asthma, CFS can also occur in children where the causes are certainly early-life events. Immune dysfunction is recognized as part of the CFS phenotype but has received comparatively less attention than aberrant neurological or endocrine function. However, recent research results suggest that early life immune insults (ELII) including developmental immunotoxicity (DIT), which is induced by xenobiotics, may offer an important clue to the origin(s) of CFS. The developing immune system is a sensitive and novel target for environmental insult (xenobiotic, infectious agents, stress) with major ramifications for postnatal health risks. Additionally, many prenatal and early postnatal neurological lesions associated with postnatal neurobehavioral diseases are now recognized as linked to prenatal immune insult and inflammatory dysregulation. This review considers the potential role of ELII including DIT as an early-life component of later-life CFS.