Decreased thymus size in formula-fed infants compared with breastfed infants

Human milk feeding practices and serum immune profiles of one-year-old infants in the CHILD birth cohort study

BACKGROUND

Breastfeeding and human milk consumption are associated with immune system development; however, the underlying mechanisms and the impact of different infant feeding practices are unclear.

OBJECTIVE

This study aimed to investigate how current human milk feeding (HMF) status is related to infant immune biomarker profiles, and explore relationships with HMF history (i.e., duration, exclusivity, and method: directly from the breast, or pumped and bottled).

METHODS

This observational birth cohort study involved 605 infants from the Canadian CHILD Cohort Study. Infant feeding was captured from hospital birth records and parent questionnaires. Ninety-two biomarkers reflecting immune system activity and development were measured in serum collected at one year (12.6±1.4 months) using the Olink Target 96 Inflammation panel. Associations were determined using multivariable regression (adjusted for sex, time until blood sample centrifugation, and study site).

RESULTS

Nearly half (42.6%) of infants were still HMF at the time of blood sampling. Compared to non-HMF infants, HMF infants had higher levels of serum Fibroblast Growth Factor 21 (FGF-21, adjusted standardized β-coefficient=0.56; 95%CI=0.41,0.72), Cluster of Differentiation 244 (CD244, β=0.35; 0.19,0.50), Chemokine Ligand 6 (CXCL6, β=0.34; 0.18,0.50), and Chemokine Ligand 20 (CCL20, β=0.26; 0.09,0.42), and lower Extracellular Newly Identified Receptor for Advanced Glycation End-Products Binding Protein (EN-RAGE, β=-0.16; -0.29,-0.03). Among non-HMF infants, serum Interleukin 7 (IL-7) had a marginally positive association with past HMF duration (β=0.05; 0.02,0.08) that persisted for up to five months post-HMF cessation. Exclusive HMF duration and HMF method (at three months of age) were not associated with any biomarkers.

CONCLUSIONS

Current HMF status and (to a lesser extent) HMF history are associated with several inflammation-associated biomarkers in one-year-old infants. These results provide new evidence that HMF impacts immune activity and development and suggest hypotheses about the underlying mechanisms. They also highlight the importance of including current HMF status in immune-system-focused infant serum proteomic studies.

Exclusive breastfeeding may be a protective factor in individuals with familial multiple sclerosis. A population registry-based case-control study

BACKGROUND

Multiple sclerosis (MS) is an immune-mediated disease that affects the central nervous system, which most likely results from the interplay between environmental and genetic factors. The aim of our study was to assess the effect of breastfeeding on the risk of developing familial multiple sclerosis (fMS) in persons with positive MS history, being the first such investigation performed in fMS cohort.

METHODS

A case-control study based on the Belgrade population MS Registry was conducted. Cases for the sporadic MS (sMS) control group were randomly selected from the Registry, and matched with individuals with fMS at a ratio of 1:1. Spouses of the persons with fMS were included as a healthy control (HC) group. A specific questionnaire that was previously validated was used to obtain the data. To evaluate risk factors associated with breastfeeding for fMS occurrence compared with sMS and HC, multinomial regression analysis was performed to compute the relative risk ratios (RRR) along with 95% confidence intervals (95% CI). The analysis was afterwards repeated, stratified by sex. Both models were adjusted for potential confounding factors.

RESULTS

A total of 393 participants were included in our case-control study, 131 per group. There were more individuals who were exclusively breastfed longer than six months in the sMS group compared to fMS group (RRR 2.01, 95% CI 1.22-3.32). After stratification by sex, exclusive breastfeeding was shown to be a protective factor for fMS only in male population, for individuals breastfed ≥4 months. The results of both the main and stratified analysis remained robust after adjustment.

CONCLUSION

Our study findings indicate that breastfeeding reduces the risk of MS in infants with family history of the disease, although this protective effect may be limited to the male population. Further investigation into the differences in risk factors between fMS and sMS is warranted to gain a more comprehensive understanding of the disease.

Breast Milk: A Meal Worth Having

A mother is gifted with breast milk, the natural source of nutrition for her infant. In addition to the wealth of macro and micro-nutrients, human milk also contains many microorganisms, few of which originate from the mother, while others are acquired from the mouth of the infant and the surroundings. Among these microbes, the most commonly residing bacteria are Staphylococci, Streptococci, Lactobacilli and Bifidobacteria. These microorganisms initiate and help the development of the milk microbiota as well as the microbiota of the gastrointestinal tract in infants, and contribute to developing immune regulatory factors such as cytokines, growth factors, lactoferrin among others. These factors play an important role in reducing the risk of developing chronic diseases like type 2 diabetes, asthma and others later in life. In this review, we will summarize the known benefits of breastfeeding and highlight the role of the breast milk microbiota and its cross-talk with the immune system in breastfed babies during the early years of life.

Impact of antenatal corticosteroid exposure on thymus size in premature infants

BACKGROUND

This study examined the effect of corticosteroids on the thymic index (TI) and the thymus/weight index (TWI) in infants exposed to antenatal corticosteroids (ACS).

METHODS

This prospective study was conducted between August 2014 and October 2018. A thymus ultrasound was performed to assess thymus size on the second day of life. Thymus size was assessed as TI and TWI.

RESULTS

In total, 167 neonates (≤34 weeks gestation)  constituted the study population, including 94 ACS-exposed infants and 73 untreated infants. The treatment group exhibited significantly lower birth weight and significantly shorter birth length than the ACS (-) group. Therefore, TI was smaller in the treatment group than in the untreated group (6.96 ± 4.05 cm³ vs. 5.64 ± 3.39 cm³). The TWI was 3.69 ± 1.8 cm³/kg in the ACS (-) group versus 3.32 ± 1.56 cm³/kg in the ACS (+) group. The median anteroposterior diameter of the right lobe was 1.33 cm (range, 0.45-2.40) in the ACS (-) group compared to 1.15 cm (range, 0.47-2.40) in the ACS (+) group. The median anteroposterior diameter of the left lobe was 1.40 cm (range, 0.43-2.20) in the ACS (-) group and 1.19 cm (range, 0.32-2.36) in the ACS (+) group. The median largest sagittal area was 2.64 cm² (range, 0.5-5.46) in the ACS (-) group versus 2.20 cm² (range, 0.55-5.90) in the ACS (+) group.

CONCLUSION

We found that TWI was not significantly changed by ACS exposure in premature infants.

The Role of CD4+ T Cells and Microbiota in the Pathogenesis of Asthma

Asthma, a chronic respiratory disease involving variable airflow limitations, exhibits two phenotypes: eosinophilic and neutrophilic. The asthma phenotype must be considered because the prognosis and drug responsiveness of eosinophilic and neutrophilic asthma differ. CD4+ T cells are the main determinant of asthma phenotype. Th2, Th9 and Tfh cells mediate the development of eosinophilic asthma, whereas Th1 and Th17 cells mediate the development of neutrophilic asthma. Elucidating the biological roles of CD4+ T cells is thus essential for developing effective asthma treatments and predicting a patient's prognosis. Commensal bacteria also play a key role in the pathogenesis of asthma. Beneficial bacteria within the host act to suppress asthma, whereas harmful bacteria exacerbate asthma. Recent literature indicates that imbalances between beneficial and harmful bacteria affect the differentiation of CD4+ T cells, leading to the development of asthma. Correcting bacterial imbalances using probiotics reportedly improves asthma symptoms. In this review, we investigate the effects of crosstalk between the microbiota and CD4+ T cells on the development of asthma.

Thymus size in children with moderate malnutrition: a cohort study from Burkina Faso

BACKGROUND

Moderate acute malnutrition (MAM) affects millions of children, increasing their risk of dying from infections. Thymus atrophy may be a marker of malnutrition-associated immunodeficiency, but factors associated with thymus size in children with MAM are unknown, as is the effect of nutritional interventions on thymus size.

METHODS

Thymus size was measured by ultrasound in 279 children in Burkina Faso with MAM, diagnosed by low mid-upper arm circumference (MUAC) and/or low weight-for-length z-score (WLZ), who received 12 weeks treatment with different food supplements as part of a randomized trial. Correlates of thymus size and of changes in thymus size after treatment, and after another 12 weeks of follow-up were identified.

RESULTS

Thymus size correlated positively with age, anthropometry and blood haemoglobin, and was smaller in children with malaria. Children with malnutrition diagnosed using MUAC had a smaller thymus than children diagnosed based on WLZ. Thymus size increased during and after treatment, similarly across the different food supplement groups.

CONCLUSIONS

In children with MAM, the thymus is smaller in children with anaemia or malaria, and grows with recovery. Assuming that thymus size reflects vulnerability, low MUAC seems to identify more vulnerable children than low WLZ in children with MAM.

IMPACT

Thymus atrophy is known to be a marker of the immunodeficiency associated with malnutrition in children. In children with moderate malnutrition, we found the thymus to be smaller in children with anaemia or malaria. Assuming that thymus size reflects vulnerability, low MUAC seems to identify more vulnerable children than low weight for length. Thymus atrophy appears reversible with recovery from malnutrition, with similar growth seen in children randomized to treatment with different nutritional supplements.

Effect of probiotics on thymus size and markers of infection in late infancy: a randomized controlled trial

BACKGROUND

Probiotics are known to stimulate the immune system but the effect on thymus size in late infancy is unknown. We examined the effect of probiotics on thymus size and C-reactive protein (CRP) in healthy Danish infants starting daycare. We further examined associations between thymus size, CRP and recent infections.

METHODS

The study included 186 children randomized to a combination of Lactobacillus rhamnosus, LGG® and Bifidobacterium animalis spp. lactis, BB-12® or placebo for 6 months. Thymus size, assessed as thymus index (TI) and thymus weight index (TWI), was measured by ultrasound at baseline and at endpoint. Blood samples were drawn to measure CRP. Infections were parent-reported.

RESULTS

There was no significant difference in thymus size between the probiotic group and placebo (p ≥ 0.248) but TWI tended to be higher in the probiotic group corresponding to 5% higher than placebo (p = 0.068) in an adjusted model. There was no effect of probiotics on CRP (p = 0.331). At the endpoint, thymus size was inversely associated with CRP (p ≤ 0.040), diarrhea (p ≤ 0.050), and TI was also associated with the absence from daycare due to respiratory or gastrointestinal infections (p = 0.010).

CONCLUSION

The probiotic intervention had no effect on thymus size or CRP in Danish children at the age of starting daycare.

IMPACT

Overall there was no effect on thymus size of a combination of Lactobacillus rhamnosus, LGG® and Bifidobacterium animalis spp. lactis, BB-12® administered to Danish children starting daycare. This study examines the effect of probiotics on thymus size in healthy children when they start daycare thus exposed for infections while their immune system is still developing. This has to our knowledge not been described before. We found no significant difference in thymus size between the probiotic and placebo groups, but for thymus weight index, there was a trend. This should be investigated further in studies designed for this as primary outcome.

Thymus size and its correlates among children admitted with severe acute malnutrition: a cross-sectional study in Uganda

Background

Malnutrition continues to be a major cause of mortality and morbidity among children in resource limited settings. Children with severe acute malnutrition (SAM) experience severe thymus atrophy, possibly reflecting poor immune function. This immune dysfunction is responsible for the severe infections they experience which lead to mortality. Since their immune dysfunction is not fully understood and there has been a lapse in research in this field, more research is needed. Knowing the correlates of thymus size may help clinicians identify those with more severe atrophy who might have more severe immune impairment. We aimed to describe thymus size and its correlates at admission among children hospitalized with SAM.

Methods

This cross-sectional study involved children 6-59 months admitted with complicated SAM in Mulago National Referral Hospital. Well-nourished children from same communities were used as a community reference group for thymus size. At admission, thymus size was measured by ultrasound scan. Demographic, clinical and laboratory variables were identified at admission. A linear regression model was used to determine correlates of thymus size among children with SAM.

Results

Among 388 children with SAM, the mean age was 17±8.5 months and 58% were boys. The mean thymus size was 3.14 (95% CI 2.9; 3.4) cm² lower than that of the 27 healthy community reference children (1.06 vs 4.2 cm², p<0.001) when controlled for age. Thymus size positively correlated with current breastfeeding (0.14, 95% CI 0.01, 0.26), anthropometric measurements at admission (weight, length, mid-upper-arm circumference, weight-for-height Z scores and length-for-age Z scores) and suspected tuberculosis (0.12, 95% CI 0.01; 0.22). Thymus size negatively correlated with > 2 weeks duration of sickness (-0.10; 95% CI -0.19; -0.01).

Conclusion

The thymus is indeed a barometer for nutrition since all anthropometric measurements and breastfeeding were associated with bigger thymus. The immune benefits of breastfeeding among children with SAM is underscored. Children with longer duration of illness had a smaller thymus gland indicating that infections have a role in the cause or consequence of thymus atrophy.

Increased thymus weight in sudden infant death syndrome compared to controls: The role of sub-clinical infections

OBJECTIVE

The goal of the present investigation is to analyze thymus, brain, heart, liver, and kidney weights in SIDS victims compared to controls.

BACKGROUND

Epidemiologic risk factors for SIDS (eg, male gender, genetic, obstetric, environmental, smoke exposure, nonbreastfeeding, etc.) are consistent with an infectious process underlying many of these deaths.

METHODS

Data from autopsy reports on 585 SIDS victims and comparison deaths (n = 294 control, n = 291 SIDS) were analyzed. Cases were obtained from Australia (n = 184 controls, n = 98 SIDS) and Russia (n = 122 controls, n = 181 SIDS). Log₁₀ transform of thymus and other organ weights was computed because variables were skewed. Multivariate analysis of variance (MANOVA) of standardized log values were age-adjusted by multivariate analysis of covariance (MANCOVA). The standardized log₁₀ thymus residual adjusted for age, brain and liver weights was computed for the final analysis.

RESULTS

After controlling for age by MANCOVA, thymus, body, brain and liver weights were significantly higher among SIDS compared to non-SIDS victims. The largest difference as between covariate-adjusted log₁₀ non-SIDS thymus weight differed (mean = 1.423, 95% CI: 1.393-1.452) and log₁₀ non-SIDS thymus weight (mean = 1.269, 95% CI: 1.243-1.294) were significantly different (P < .0001). Heart weight was significantly lower in SIDS victims.

DISCUSSION

When adjusted for confounders (age, body, and organ weights), SIDS victims have a significantly heavier thymus and brain compared to non-SIDS controls who died of trauma. This finding supports previously published studies that link infection to SIDS deaths.

Relationship between Breastfeeding, Birth History, and Acute Pyelonephritis in Infants

BACKGROUND

Although the clinical importance of the immunological benefits of breastfeeding has been emphasized for decades, their direct relationship with acute pyelonephritis (APN) is still not clear. Our goal was to determine whether breastfeeding truly provides protection against APNs, while investigating the effects of other factors such as sex, age, mode of delivery, and birth weight on APN.

METHODS

A total of 62 infants under 6 months of age who had both microbiologically and radiologically-confirmed APN were enrolled in the case group. Healthy infants (n = 178) who visited the hospital for scheduled vaccinations were enrolled in the control group. The following participant characteristics were compared between the case and control groups: age, sex, birth order among siblings, feeding methods, weight percentile by month, birth weight percentile by gestational age, gestational age at birth, and mode of delivery.

RESULTS

Babies exclusively fed with manufactured infant formulae before 6 months of age had significantly higher risk for APN than breastfed or mixed-fed infants (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.687-7.031; P = 0.001). Firstborn babies had lower risk for APN than 2nd- or 3rd-born babies (OR, 0.43; 95% CI, 0.210-0.919). Other factors that increased the risk for APN were low birth weight percentiles (OR, 8.33; 95% CI, 2.300-30.166) and birth via caesarean section (OR, 2.32; 95% CI, 1.097-4.887). There were more preterm births in the case group (10.9% vs. 1.7%; P = 0.002), but this did not increase the risk for APN (OR, 4.47; P = 0.063).

CONCLUSION

Feeding exclusively with formula before 6 months of age was related to higher risk for APN, which demonstrates that breastfeeding has a protective effect against APN. The other risk factors for APN were birth order (≥ 2nd-born), low birth weight, and birth via caesarean section.

Maternal Leukocytes and Infant Immune Programming during Breastfeeding

The fetal immune system develops in a rather sterile environment relative to the outside world and, therefore, lacks antigenic education. Soon after birth, the newborn is exposed to the hostile environment of pathogens. Recently, animal- and limited human-based studies have indicated that help from the mother, upon transfer of leukocytes and their products via breast milk feeding, greatly assists the newborn's immune system. Here, I discuss the newest advances on how milk leukocytes impact early life immunity, with an emphasis on the development of the infant T cell repertoire and early immune responses in the periphery and gut-associated lymphoid tissue. A deeper understanding of these novel mechanistic insights may inform potential translational approaches to improving immunity in infants.

Enhancement of immune maturation in suckling rats by leptin and adiponectin supplementation

Leptin and adiponectin, adipokines present in breast milk, have shown immunomodulatory properties. The current study aimed to ascertain whether a nutritional supplementation with leptin or adiponectin in neonatal rats was able to influence the maturation of the systemic immune response in early life. To achieve this, suckling Wistar rats were supplemented with either leptin (0.7 μg/kg/day) or adiponectin (35 μg/kg/day) during the whole suckling period. Plasmatic immunoglobulins were quantified, and spleen lymphocyte composition and their ability to proliferate and release cytokines were evaluated during (day 14) and at the end (day 21) of the suckling period. Rats fed with either adipokine showed higher plasma IgM and IgG1 concentrations and adiponectin supplementation also increased IgG2a at both studied days (P < 0.05). With regard to the lymphocyte composition, both adipokine supplementations increased T cell proportion and both CD4⁺ and CD8⁺ T cell subsets after two weeks of supplementation (P < 0.05). Moreover, only leptin administration increased NK and NKT cell proportions at the end of the suckling period. Finally, both adipokines influenced the cytokine secretion pattern by splenocytes. In conclusion, these results suggest that leptin and adiponectin play a role in the maturation of the systemic immune response during the suckling period.

Breast milk interleukin-7 and thymic gland development in infancy

PURPOSE

Interleukin-7 (IL-7) is known to be important for lymphocyte development. We sought to investigate the maternal breast milk IL-7 expression to explore its impact on thymus development in infants.

METHODS

We conducted a prospective study on three groups of healthy infants classified into exclusively breast-fed (n = 19), formula-fed (n = 17) and mixed-fed (n = 19) infants. They were investigated at 2, 4 and 6 months of age for thymic indices by ultrasonography, T lymphocyte subsets enumeration by flowcytometry and breast milk IL-7 levels.

RESULTS

Thymic indices were higher at the age of 2 and 6 months in the exclusively breast-fed infants (mean ± SD 22.4 ± 2.1, 26.2 ± 2.7 mm³, respectively) and mixed-fed infants (mean ± SD 22 ± 3.2, 25 ± 3.2, respectively) as compared to formula-fed infants (mean ± SD 17.9 ± 3.7, 21.6 ± 3.9 respectively); p < 0.001. In the exclusively breast-fed infants, IL-7 levels correlated positively to thymic indices and CD3+ T cell numbers at 2 months of age. Positive correlations were elicited in the mixed-fed group at 2, 4 and 6 months of age for thymic indices and at 6 months for CD3+ cells.

CONCLUSION

Breast milk and/or its IL-7 content have a significant positive impact on thymic development. Our conclusions are limited by the sample size and short duration of follow-up. What is known is that breast milk has a trophic role in thymic development and contains IL-7. What is new is that there is positive correlation between breast milk IL-7 concentration and thymic development and lymphocyte output; variation of IL-7 levels with type of feeding (exclusive breast feeding/mixed breast and formula feeding) and with time postnatally.

Cross-Species Meta-Analysis of Transcriptomic Data in Combination With Supervised Machine Learning Models Identifies the Common Gene Signature of Lactation Process

Lactation, a physiologically complex process, takes place in mammary gland after parturition. The expression profile of the effective genes in lactation has not comprehensively been elucidated. Herein, meta-analysis, using publicly available microarray data, was conducted identify the differentially expressed genes (DEGs) between pre- and post-peak milk production. Three microarray datasets of Rat, Bos Taurus, and Tammar wallaby were used. Samples related to pre-peak (n = 85) and post-peak (n = 24) milk production were selected. Meta-analysis revealed 31 DEGs across the studied species. Interestingly, 10 genes, including MRPS18B, SF1, UQCRC1, NUCB1, RNF126, ADSL, TNNC1, FIS1, HES5 and THTPA, were not detected in original studies that highlights meta-analysis power in biosignature discovery. Common target and regulator analysis highlighted the high connectivity of CTNNB1, CDD4 and LPL as gene network hubs. As data originally came from three different species, to check the effects of heterogeneous data sources on DEGs, 10 attribute weighting (machine learning) algorithms were applied. Attribute weighting results showed that the type of organism had no or little effect on the selected gene list. Systems biology analysis suggested that these DEGs affect the milk production by improving the immune system performance and mammary cell growth. This is the first study employing both meta-analysis and machine learning approaches for comparative analysis of gene expression pattern of mammary glands in two important time points of lactation process. The finding may pave the way to use of publically available to elucidate the underlying molecular mechanisms of physiologically complex traits such as lactation in mammals.

Does Breast Milk Nurture T Lymphocytes in Their Cradle?

Breast feeding has been associated with improved infant outcomes in multiple aspects, including immune outcomes such as infections and potentially atopy and autoimmunity. However associations do not necessarily implicate cause and effect and at this point, exactly how breast feeding and components of breast milk may modulate the infant's immune compartment remains unclear, especially in humans. Some lines of evidence suggest that breastfeeding affects the development of the infant's thymus, a critical organ for T cell development. This may be a direct effect mediated by breast milk components or alternatively, a secondary effect from the impact of breast feeding on the infant's gut microbiome. Here we discuss the potential mechanisms and impact of this association between breast feeding and thymic development.

Breastfeeding and autoimmunity: Programing health from the beginning

Breast milk is not only a completely adapted nutrition source for the newborn but also an impressive array of immune-active molecules that afford protection against infections and shape mucosal immune responses. Decisive imprinting events might be modulated during the first months of life with potential health long-term effects, enhancing the importance of breastfeeding as a major influence on the immune system correct development and modifying disease susceptibility. The aim of this review was to clarify the link between breastfeeding and autoimmune diseases, inquiring the related mechanisms, based on data available in the literature. Being breastfed was associated with a lower incidence of diabetes, celiac disease, multiple sclerosis and asthma, explained by the protection against early infections, anti-inflammatory properties, antigen-specific tolerance induction, and regulation of infant's microbiome. The protective role of human milk in idiopathic juvenile arthritis, rheumatoid arthritis, and inflammatory bowel diseases remains controversial. On the other hand, the breastfeeding mother faces a health-challenging period in life. High levels of prolactin may lead either to the development of autoimmune diseases in susceptible mothers or exacerbations of current immune-mediated disorders. These features raise the question if mothers with autoimmune diseases, mainly systemic lupus erythematosus, should avoid breastfeeding.

Human Milk and Allergic Diseases: An Unsolved Puzzle

There is conflicting evidence on the protective role of breastfeeding in relation to the development of allergic sensitisation and allergic disease. Studies vary in methodology and definition of outcomes, which lead to considerable heterogeneity. Human milk composition varies both within and between individuals, which may partially explain conflicting data. It is known that human milk composition is very complex and contains variable levels of immune active molecules, oligosaccharides, metabolites, vitamins and other nutrients and microbial content. Existing evidence suggests that modulation of human breast milk composition has potential for preventing allergic diseases in early life. In this review, we discuss associations between breastfeeding/human milk composition and allergy development.

Effects of osteopontin-enriched formula on lymphocyte subsets in the first 6 months of life: a randomized controlled trial

BackgroundHuman milk is rich in osteopontin (OPN), which has immunomodulatory functions.MethodsIn a randomized controlled trial, standard formula (SF) and the same formula with 65 mg of OPN/L (F65) or 130 mg of OPN/L (F130), representing ~50 and 100% of the OPN concentration in human milk, were compared. We examined frequencies and composition of peripheral blood immune cells by four-color immunoflow cytometry of formula-fed infants at ages 1, 4, and 6 months, and compared them with a breastfed (BF) reference group.ResultsThe F130 group had increased T-cell proportions compared with the SF (P=0.036, average effect size 0.51) and F65 groups (P=0.008, average effect size 0.65). Compared with the BF group, the monocyte proportions were increased in the F65 (P=0.001, average effect size 0.59) and F130 (P=0.006, average effect size 0.50) groups, but were comparable among the formula groups.ConclusionOPN in an infant formula at a concentration close to that of human milk increased the proportion of circulating T cells compared with both SF and formula with added OPN at ~50% of the concentration in human milk. This suggests that OPN may favorably influence immune ontogeny in infancy and that the effects appear to be dose-dependent.

Correlates of thymus size and changes during treatment of children with severe acute malnutrition: a cohort study

Background

The impairment of immune functions associated with malnutrition may be one reason for the high mortality in children with severe acute malnutrition (SAM), and thymus atrophy has been proposed as a marker of this immunodeficiency. The aim of this study was to identify nutritional and clinical correlates of thymus size in children with SAM, and predictors of change in thymus size with nutritional rehabilitation.

Methods

In an observational study among children aged 6–59 months admitted with SAM in Uganda, we measured thymus area by ultrasound on hospital admission to treatment with F75 and F100, on hospital discharge and after 8 weeks of nutritional rehabilitation with ready-to-use therapeutic food, as well as in well-nourished healthy children. We investigated anthropometric, clinical, biochemical and treatment-related correlates of area and growth of the thymus.

Results

Eighty-five children with SAM with a median age of 16.5 months were included. On admission 27% of the children had a thymus undetectable by ultrasound. Median thymus area was 1.3 cm² in malnourished children, and 3.5 cm² in healthy children (p < 0.001). Most anthropometric z-scores, hemoglobin and plasma phosphate correlated positively with thymus area. Thymus area correlated negatively with caretaker-reported severity of illness, plasma α-1 acid glycoprotein, and C-reactive protein >5 mg/L. At follow-up after 8 weeks, median thymus area had increased to 2.5 cm² (p < 0.001). Increase in thymus area during treatment was associated with simultaneous increase in mid-upper-arm circumference, with 0.29 cm² higher increase in thymus area per cm larger increment in MUAC (p = 0.03). Children whose F-75 had partially been replaced by rice porridge during their hospital admission had less increase in thymus area after 8 weeks.

Conclusion

Malnutrition and inflammation are associated with thymus atrophy, and thymus area seems positively associated with plasma phosphate. Substituting therapeutic formula with unfortified rice porridge with the aim of alleviating diarrhea may impair regain of thymus size with nutritional rehabilitation. This calls for research into possible effects of phosphate status on thymus size and other immunological markers.

Trial registration

The study is based on data from the FeedSAM study, ISRCTN55092738.

Homage to the ‘H’ in developmental origins of health and disease

Abundant evidence exists linking maternal and paternal environments from pericopconception through the postnatal period to later risk to offspring diseases. This concept was first articulated by the late Sir David Barker and as such coined the Barker Hypothesis. The term was then mutated to Fetal Origins of Adult Disease and finally broadened to developmental origins of adult health and disease (DOHaD) in recognition that the perinatal environment can shape both health and disease in resulting offspring. Developmental exposure to various factors, including stress, obesity, caloric-rich diets and environmental chemicals can lead to detrimental offspring health outcomes. However, less attention has been paid to date on measures that parents can take to promote the long-term health of their offspring. In essence, have we neglected to consider the ‘H’ in DOHaD? It is the ‘H’ component that should be of primary concern to expecting mothers and fathers and those seeking to have children. While it may not be possible to eliminate exposure to all pernicious factors, prevention/remediation strategies may tip the scale to health rather than disease. By understanding disruptive DOHaD mechanisms, it may also illuminate behavioral modifications that parents can adapt before fertilization and throughout the neonatal period to promote the lifelong health of their male and female offspring. Three possibilities will be explored in the current review: parental exercise, probiotic supplementation and breastfeeding in the case of mothers. The ‘H’ paradigm should be the focus going forward as a healthy start can indeed last a lifetime.

Bacillus Calmette-Guérin immunisation at birth and morbidity among Danish children: A prospective, randomised, clinical trial

BACKGROUND

Studies from low-income countries report positive non-specific effects of early Bacillus Calmette-Guérin (BCG) immunisation on childhood health and survival. Neonatal immunisation with BCG may prime the immune system and offer partial protection against other infectious and possibly allergic diseases. The potential clinical value of these non-specific effects has not yet been examined in a large randomised trial in high-income countries.

METHODS

The Danish Calmette Study is a multicentre randomised clinical trial conducted between October 2012 and November 2015. Within the first 7 days of life, infants were randomly assigned to intra-dermal vaccination with BCG or no intervention. At 3 and 13 months of age structured telephone interviews and clinical examinations of the children were conducted. In a subgroup of children blood samples were drawn and stool samples collected at age 4 days, 3 and 13 months. Thymus index was assessed by ultrasound in a subgroup at randomisation and at 3 months. The primary study outcome is hospitalisation within the first 15 months of life as assessed in Danish health registers. Secondary outcomes include infectious disease hospitalisations, wheezing, eczema, use of prescribed medication, growth, development, thymus index, T- and B-cell subpopulations assessed by flow cytometry, in vitro cytokine responses and specific antibody responses to other vaccines. Adverse reactions were registered.

DISCUSSION

With participation of 4184 families and more than 93% adherence to clinical follow-up at 3 and 13 months, this randomised clinical trial has the potential to create evidence regarding non-specific effects of BCG vaccination in a high-income setting.

Gene expression in the mammary gland of the tammar wallaby during the lactation cycle reveals conserved mechanisms regulating mammalian lactation

The tammar wallaby (Macropus eugenii), an Australian marsupial, has evolved a different lactation strategy compared with eutherian mammals, making it a valuable comparative model for lactation studies. The tammar mammary gland was investigated for changes in gene expression during key stages of the lactation cycle using microarrays. Differentially regulated genes were identified, annotated and subsequent gene ontologies, pathways and molecular networks analysed. Major milk-protein gene expression changes during lactation were in accord with changes in milk-protein secretion. However, other gene expression changes included changes in genes affecting mRNA stability, hormone and cytokine signalling and genes for transport and metabolism of amino acids and lipids. Some genes with large changes in expression have poorly known roles in lactation. For instance, SIM2 was upregulated at lactation initiation and may inhibit proliferation and involution of mammary epithelial cells, while FUT8 was upregulated in Phase 3 of lactation and may support the large increase in milk volume that occurs at this point in the lactation cycle. This pattern of regulation has not previously been reported and suggests that these genes may play a crucial regulatory role in marsupial milk production and are likely to play a related role in other mammals.

Breastfeeding and risk of infections at 6 years

BACKGROUND

Previous studies have shown that breastfeeding is associated with reductions in the risk of common infections among infants; however, whether breastfeeding confers longer term protection is inconclusive.

METHODS

We linked data from the 2005-2007 IFPS II (Infant Feeding Practices Study II) and follow-up data collected when the children were 6 years old. Multivariable logistic regression was used, controlling for sociodemographic variables, to examine associations of initiation, duration, exclusivity of breastfeeding, timing of supplementing breastfeeding with formula, and breast milk intensity (proportion of milk feedings that were breast milk from age 0-6 months) with maternal reports of infection (cold/upper respiratory tract, ear, throat, sinus, pneumonia/lung, and urinary) and sick visits in the past year among 6-year-olds (N = 1281).

RESULTS

The most common past-year infections were colds/upper respiratory tract (66%), ear (25%), and throat (24%) infections. No associations were found between breastfeeding and colds/upper respiratory tract, lung, or urinary tract infections. Prevalence of ear, throat, and sinus infections and number of sick visits differed according to breastfeeding duration, exclusivity, and timing of supplementing breastfeeding with formula (P < .05). Among children ever breastfed, children breastfed for ≥9 months had lower odds of past-year ear (adjusted odds ratio [aOR]: 0.69 [95% confidence interval (95% CI): 0.48-0.98]), throat (aOR: 0.68 [95% CI: 0.47-0.98]), and sinus (aOR: 0.47 [95% CI: 0.30-0.72]) infections compared with those breastfed >0 to <3 months. High breast milk intensity (>66.6%) during the first 6 months was associated with lower odds of sinus infection compared with low breast milk intensity (<33.3%) (aOR: 0.53 [95% CI: 0.35-0.79]).

CONCLUSIONS

This prospective longitudinal study suggests that breastfeeding may protect against ear, throat, and sinus infections well beyond infancy.

The immune system in children with malnutrition--a systematic review

BACKGROUND

Malnourished children have increased risk of dying, with most deaths caused by infectious diseases. One mechanism behind this may be impaired immune function. However, this immune deficiency of malnutrition has not previously been systematically reviewed.

OBJECTIVES

To review the scientific literature about immune function in children with malnutrition.

METHODS

A systematic literature search was done in PubMed, and additional articles identified in reference lists and by correspondence with experts in the field. The inclusion criteria were studies investigating immune parameters in children aged 1-60 months, in relation to malnutrition, defined as wasting, underweight, stunting, or oedematous malnutrition.

RESULTS

The literature search yielded 3402 articles, of which 245 met the inclusion criteria. Most were published between 1970 and 1990, and only 33 after 2003. Malnutrition is associated with impaired gut-barrier function, reduced exocrine secretion of protective substances, and low levels of plasma complement. Lymphatic tissue, particularly the thymus, undergoes atrophy, and delayed-type hypersensitivity responses are reduced. Levels of antibodies produced after vaccination are reduced in severely malnourished children, but intact in moderate malnutrition. Cytokine patterns are skewed towards a Th2-response. Other immune parameters seem intact or elevated: leukocyte and lymphocyte counts are unaffected, and levels of immunoglobulins, particularly immunoglobulin A, are high. The acute phase response appears intact, and sometimes present in the absence of clinical infection. Limitations to the studies include their observational and often cross-sectional design and frequent confounding by infections in the children studied.

CONCLUSION

The immunological alterations associated with malnutrition in children may contribute to increased mortality. However, the underlying mechanisms are still inadequately understood, as well as why different types of malnutrition are associated with different immunological alterations. Better designed prospective studies are needed, based on current understanding of immunology and with state-of-the-art methods.

Thymic size correlates with cord blood zinc levels in low-birth-weight newborns

Thymus is essential for immunity as it provides environment for T cell differentiation and maturation. There is limited information on various factors which determine thymic size at birth. We studied the influence of cord blood zinc and copper levels and maternal and neonatal nutritional status on thymic size in term low-birth-weight (LBW) newborns. A prospective observational study on 44 term LBW (<2,500 g) newborns (cases) and 71 gestational age-matched newborns weighing ≥2,500 g (controls). Sonographically determined thymic index was correlated to cord blood zinc and copper levels and maternal and neonatal nutritional status. Thymic index measured 3.74 ± 1.57 cm(3) in LBW newborns compared to 4.90 ± 2.33 cm(3) in normal-birth-weight newborns. Thymic index was significantly correlated to cord blood zinc levels but not to cord blood copper levels and had linear relationship to the maternal body mass index and midarm circumference and neonatal anthropometric parameters.

CONCLUSION

Thymic index is linearly related to cord blood zinc levels and maternal and neonatal nutritional status. Compared to thymic size in the Western newborns, the thymus is less than half in size in Indian newborns of normal birth weight. Reduced thymic size in Indian newborns in general and LBW infants in particular may have consequences for their immune competence and the risk of infections. Improving nutrition of pregnant women, particularly zinc nutriture might favorably influence thymic size in their offspring.

Disproportionate early fetal growth predicts postnatal thymic size in humans

Prenatal events can affect neonatal thymus size and adult immune function. The causal insults are unknown, although fetal nutrient restriction is suspected. We used ultrasound at three time points during pregnancy (14, 19 and 30 weeks) to measure the growth of six fetal dimensions in rural Bangladeshi women participating in the Maternal and Infant Nutrition Interventions, Matlab study. Postnatal ultrasound was used to calculate thymic index (TI) at birth, 2, 6 and 12 m. Of the 3267 women recruited, 2861 participated by providing data at least at one fetal biometry and one TI time point. Patterns of fetal growth were summarized using principal components calculated from fetal dimension z-scores. Random effects regression, controlling for infant size and season of measurement were used to relate these patterns to TI. We found that smaller leg length relative to head circumference, characteristic of head-sparing growth restriction, was predictive of lower TI. This association was significant at all time points but strongest in earlier pregnancy. Each standard deviation increase in leg-head proportion was associated with an increase in TI of ∼5%. We conclude that growth patterns typical of poor fetal nutrition are associated with poor thymic development. The greater strength of this association in the first trimester is consistent with a period of vulnerability during the early ontogeny of the thymus and suggests that preventative intervention would need to be given in early pregnancy.

Formula-feeding is associated with shift towards Th1 cytokines

PURPOSE

Breast-feeding (BF) versus formula-feeding (FF) may be a factor for the development and differentiation of T-cell subsets and cytokine production in infancy and childhood. We therefore investigated T-cell subpopulations and their cytokine production by flow cytometry as well as cytokine levels in serum samples in breast-fed versus formula-fed infants and children.

METHODS

Heparinised blood was taken from 191 healthy infants and children. Peripheral blood mononuclear cells were stimulated with phorbol-mystriate-acetate and ionomycin in the presence of brefeldin. T-cell subsets and cytokines were determined by flow cytometry. Furthermore, serum concentrations of IFNγ and IL4 were measured using ELISA. An IFNγ/IL4 ratio was calculated to estimate the Th1/Th2 balance.

RESULTS

Children who were formula-fed show higher numbers of memory T and T helper cells. After stimulation, the number of IFNγ-positive memory T-cells was increased up to the age of 6 years. Breast-fed infants show higher percentages of IL4-positive T helper cells. At ELISA determination, formula-fed children showed higher IFNγ levels than breast-fed children, while IL4 levels did not differ. The IFNγ/IL4 ratio (FACS and ELISA) was elevated in formula-fed infants and children.

CONCLUSION

This systematic analysis of cytokine profiles during childhood in dependency of BF allows a better understanding of immune maturation and demonstrates the influence of early feeding on immune function throughout childhood, even after cessation of BF. FF induces a shift towards Th1 cytokines in children. This may have an influence on the development of autoimmune disease in later life.

Lactobacillus paracasei CBA L74 metabolic products and fermented milk for infant formula have anti-inflammatory activity on dendritic cells in vitro and protective effects against colitis and an enteric pathogen in vivo

The rapid expansion of commercially available fermented food products raises important safety issues particularly when infant food is concerned. In many cases, the activity of the microorganisms used for fermentation as well as what will be the immunological outcome of fermented food intake is not known. In this manuscript we used complex in vitro, ex-vivo and in vivo systems to study the immunomodulatory properties of probiotic-fermented products (culture supernatant and fermented milk without live bacteria to be used in infant formula).

We found in vitro and ex-vivo that fermented products of Lactobacillus paracasei CBA L74 act via the inhibition of proinflammatory cytokine release leaving anti-inflammatory cytokines either unaffected or even increased in response to Salmonella typhimurium. These activities are not dependent on the inactivated bacteria but to metabolic products released during the fermentation process. We also show that our in vitro systems are predictive of an in vivo efficacy by the fermented products. Indeed CBA L74 fermented products (both culture medium and fermented milk) could protect against colitis and against an enteric pathogen infection (Salmonella typhimurium). Hence we found that fermented products can act via the inhibition of immune cell inflammation and can protect the host from pathobionts and enteric pathogens. These results open new perspectives in infant nutrition and suggest that L. paracasei CBA L74 fermented formula can provide immune benefits to formula-fed infants, without carrying live bacteria that may be potentially dangerous to an immature infant immune system.

Considerations in the pharmacologic treatment and prevention of neonatal sepsis

The management of neonatal sepsis is challenging owing to complex developmental and environmental factors that contribute to inter-individual variability in the pharmacokinetics and pharmacodynamics of many antimicrobial agents. In this review, we describe (i) the changing epidemiology of early- and late-onset neonatal sepsis; (ii) the pharmacologic considerations that influence the safety and efficacy of antibacterials, antifungals, and immunomodulatory adjuvants; and (iii) the recommended dosing regimens for pharmacologic agents commonly used in the treatment and prevention of neonatal sepsis. Neonatal sepsis is marked by high morbidity and mortality, such that prompt initiation of antimicrobial therapy is essential following culture collection. Before culture results are available, combination therapy with ampicillin and an aminoglycoside is recommended. When meningitis is suspected, ampicillin and cefotaxime may be considered. Following identification of the causative organism and in vitro susceptibility testing, antimicrobial therapy may be narrowed to provide targeted coverage. Therapeutic drug monitoring should be considered for neonates receiving vancomycin or aminoglycoside therapies. For neonates with invasive fungal infections, the development of new antifungal agents has significantly improved therapeutic outcomes in recent years. Liposomal amphotericin B has been found to be safe and efficacious in patients with renal impairment or toxicity caused by conventional amphotericin B. Antifungal prophylaxis with fluconazole has also been reported to dramatically reduce rates of neonatal invasive fungal infections and to improve long-term neurodevelopmental outcomes among treated children. Additionally, several large multicenter studies are currently investigating the safety and efficacy of oral lactoferrin as an immunoprophylactic agent for the prevention of neonatal sepsis.

Thymus development and infant and child mortality in rural Bangladesh

BACKGROUND

Data from West Africa indicate that a small thymus at birth and at 6 months of age is a strong and independent risk factor for infection-related mortality up to 24 and 36 months of age, respectively. We investigated the association between thymus size (thymic index, TI) in infancy and subsequent infant and child survival in a contemporary South Asian population.

METHODS

The study focused on the follow-up of a randomized trial of prenatal nutritional interventions in rural Bangladesh (ISRCTN16581394), with TI measured longitudinally in infancy (at birth and weeks 8, 24 and 52 of age) and accurate recording of mortality up to 5 years of age.

RESULTS

A total of 3267 infants were born into the Maternal and Infant Nutrition Interventions, Matlab study; data on TI were available for 1168 infants at birth, increasing to 2094 infants by 52 weeks of age. TI in relation to body size was largest at birth, decreasing through infancy. For infants with at least one measure of TI available, there were a total of 99 deaths up to the age of 5 years. No association was observed between TI and subsequent mortality when TI was measured at birth. However, an association with mortality was observed with TI at 8 weeks of age [odds ratio (OR) for change in mortality risk associated with 1 standard deviation change in TI: all deaths: OR = 0.64, 95% confidence interval (CI) 0.41, 0.98; P = 0.038; and infection-related deaths only: OR = 0.32, 95% CI 0.14, 0.74; P = 0.008]. For TI when measured at 24 and 52 weeks of age, the numbers of infection-related deaths were too few (3 and 1, respectively) for any meaningful association to be observed.

CONCLUSION

These results confirm that thymus size in early infancy predicts subsequent survival in a lower mortality setting than West Africa. The absence of an effect at birth and its appearance at 8 weeks of age suggests early postnatal influences such as breast milk trophic factors.

Normal Thymic Size and Low Rate of Infections in Human Donor Milk Fed HIV-Exposed Uninfected Infants from Birth to 18 Months of Age

Objective. To evaluate the immune function in HIV-exposed uninfected (HIV-EU) infants fed human donor milk. Methods. Ultrasound-obtained thymic index (Ti), T-lymphocyte subsets, and the number of infections were examined from birth to 18 months of age in 18 HIV-EU infants. The infants were compared to a cohort of 47 term, HIV-unexposed breastfed or formula-fed infants. Results. The thymic size at 12 months of age was not significantly different between the HIV-EU group and the control infants (P = 0.56). At 4 months of age, the HIV-EU infants had significantly fewer infections than the control infants (P < 0.001). Furthermore, in the control group, the infants exclusively breastfed at 4 months of age had significantly fewer infections at 8 months when compared to age-matched formula-fed infants (P = 0.001). Conclusion. HIV-EU infants fed human donor milk have normal growth of thymus and contract fewer infections than other healthy infants. This finding along with fewer infections in exclusively breastfed infants compared to formula-fed infants supports the beneficial effect of human milk on the immune system. We suggest, when breastfeeding is not possible, that providing human donor milk to vulnerable groups of infants will be beneficial for their maturing immune system.

Infant growth and the thymus: data from two South American native societies

The thymus plays an important role in the development of the immune system, yet little is known about the patterns and sources of variation in postnatal thymic development. The aim of this study is to contribute cross-cultural data on thymus size in infants from two South American native populations, the Tsimane of Bolivia and the Pumé of Venezuela. Thymic ultrasonography was performed and standard anthropometric measures collected from 86 Tsimane and Pumé infants. Patterns of infant growth and thymus size were compared between the two populations and the relationship between nutritional status and thymus size was assessed. Despite nearly identical anthropometric trajectories, Tsimane infants had larger thymuses than Pumé infants at all ages. Population, infant age, and infant mid-upper arm circumference were significant predictors of thymus area in the Tsimane and Pumé infants. This finding reveals a cross-cultural difference in thymus size that is not driven by nutritional status. We suggest that future studies focus on isolating prenatal and postnatal environmental factors underlying cross-cultural variation in thymic development.

Low thymic size in preterm infants in the neonatal intensive care unit, a possible marker of infection? A prospective study from birth to 1 year of age

AIM

To study the growth of the thymus in preterm infants.

METHODS

Ultrasonographic thymic size (Ti) was studied in 80 preterm infants (gestational age 24-36 weeks) from birth to discharge from the neonatal intensive care unit (NICU). Thirty-three of these infants were followed to 1 year of age.

RESULTS

At birth, the median Ti was 5.2 compared with 11.8 in term infants. At discharge, the median Ti was 10.0 and not significantly different from Ti in term infants at birth (p = 0.22). The size of the thymus was significantly associated with postmenstrual age and weight (both p < 0.01). Infections during admission were negatively associated with the size of the thymus (p < 0.01). During the first 3 months after discharge, preterm infants had a significantly higher frequency of infections than did term infants (p = 0.002); hereafter, the preterm infants had significantly fewer infections than term infants (p = 0.002). The median Ti in preterm infants and term infants at 1 year of age was 21.1 and 17.3, respectively. This difference was not statistically significant (p = 0.41).

CONCLUSIONS

Growth of thymus was not compromised by preterm birth. Ti is negatively associated with the frequency of infections in preterm neonates submitted to NICU.

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.

Interleukin 7 from maternal milk crosses the intestinal barrier and modulates T-cell development in offspring

Background

Breastfeeding protects against illnesses and death in hazardous environments, an effect partly mediated by improved immune function. One hypothesis suggests that factors within milk supplement the inadequate immune response of the offspring, but this has not been able to account for a series of observations showing that factors within maternally derived milk may supplement the development of the immune system through a direct effect on the primary lymphoid organs. In a previous human study we reported evidence suggesting a link between IL-7 in breast milk and the thymic output of infants. Here we report evidence in mice of direct action of maternally-derived IL-7 on T cell development in the offspring.

Methods and Findings

We have used recombinant IL-7 labelled with a fluorescent dye to trace the movement in live mice of IL-7 from the stomach across the gut and into the lymphoid tissues. To validate the functional ability of maternally derived IL-7 we cross fostered IL-7 knock-out mice onto normal wild type mothers. Subsets of thymocytes and populations of peripheral T cells were significantly higher than those found in knock-out mice receiving milk from IL-7 knock-out mothers.

Conclusions/Significance

Our study provides direct evidence that interleukin 7, a factor which is critical in the development of T lymphocytes, when maternally derived can transfer across the intestine of the offspring, increase T cell production in the thymus and support the survival of T cells in the peripheral secondary lymphoid tissue.

US assessment of estrogen-responsive organ growth among healthy term infants: piloting methods for assessing estrogenic activity

BACKGROUND

A mother's circulating estrogen increases over the third trimester, producing physiological effects on her newborn that wane postnatally. Estrogenization might be prolonged in newborns exposed to exogenous estrogens, such as isoflavones in soy formula.

OBJECTIVE

We evaluated ultrasonography for monitoring growth of multiple estrogen-responsive organs in healthy infants and developed organ-growth trajectories.

MATERIALS AND METHODS

We studied 38 boys (61 visits) from birth to age 6 months and 41 girls (96 visits) from birth to age 1 year using a partly cross-sectional, partly longitudinal design. We measured uterus and ovaries in girls, testes and prostate in boys, and kidneys, breasts, thymus, and thyroid in all children. We imaged all organs from the body surface in one session of < 1 h.

RESULTS

Uterine volume decreased from birth (P < 0.0001), whereas ovarian volume increased sharply until age 2 months and then decreased (P < 0.001). Testicular volume increased with age (P < 0.0001), but prostatic volume showed minimal age trend. Breast bud diameter showed no age trend in girls but declined from birth in boys (P = 0.03).

CONCLUSION

US examination of multiple estrogen-responsive organs in infants in a single session is feasible and yields volume estimates useful for assessing potential endocrine disruptor effects on organ growth.

Age-dependent clinical problems in a Norwegian national survey of patients with the 22q11.2 deletion syndrome

Patients with the 22q11.2 deletion syndrome display a wide phenotypic variation that is important for clinical follow-up. In this national survey of 60 patients (ages 1 to 54 years) diagnosed by Fluorescence in situ hybridization test, data were collected from medical records, a physical examination, and a semistructured interview. Ultrasound investigation of the kidneys was also performed. In addition, multiplex ligation probe amplification assay was performed to detect deletion size. Phenotypic features leading to the genetic diagnosis were noted. The patients showed a variety of organ malformations including 39 with heart anomalies. Only 20 individuals had been diagnosed with 22q11.2 DS in the first year of life. Four patients had renal and five males had genital malformations. The increased infection susceptibility (excluding otitis media) and most feeding difficulties subsided during early childhood. Speech difficulties started early and were a major problem for many patients at least until 10 years of age. Ten patients developed kyphoscoliosis in late childhood. In teenagers and adults, abnormal social behavior, learning disabilities, and psychiatric symptoms dominated. Our study which also includes adult patients emphasizes a marked change in challenges in individuals with the 22q11.2 deletion syndrome with increasing age.

Early-life nutritional and environmental determinants of thymic size in infants born in rural Bangladesh

Aim:

The aim was to assess the impact of nutritional status and environmental exposures on infant thymic development in the rural Matlab region of Bangladesh.

Methods:

In a cohort of N_max 2094 infants born during a randomized study of combined interventions to improve maternal and infant health, thymic volume (thymic index, TI) was assessed by ultrasonography at birth and at 8, 24 and 52 weeks of age. Data on birth weight, infant anthropometry and feeding status were also collected.

Results:

At all ages, TI was positively associated with infant weight and strongly associated with the month of measurement. Longer duration of exclusive breastfeeding resulted in a larger TI at 52 weeks. TI at birth and at 8 weeks correlated positively with birth weight, but by 24 and 52 weeks and when adjusted for infant weight this effect was no longer present. Thymic size was not affected by pre-natal maternal supplementation or by socioeconomic status but was correlated to arsenic exposure during pregnancy.

Conclusion:

In this population of rural Bangladeshi infants, thymic development is influenced by both nutritional and environmental exposures early in life. The long-term functional implications of these findings warrant further investigation.

Thymus size at 6 months of age and subsequent child mortality

OBJECTIVE

To examine determinants of thymus size at age 6 months and investigate whether thymus size at this age is a determinant of subsequent mortality.

STUDY DESIGN

Thymus size was measured by transsternal sonography in 923 6-month-old children participating in a measles vaccination trial in Guinea-Bissau.

RESULTS

Thymus size was strongly associated with anthropometric measurements. Boys had larger thymuses than girls, controlling for anthropometry. Crying during sonography made the thymus appear smaller. Children who were not vaccinated with Bacille Calmette-Guérin (BCG) or were vaccinated with BCG in the preceding 4 weeks before inclusion into the study had larger thymuses. Children who had malaria or had been treated with chloroquine or Quinimax in the previous week before inclusion had smaller thymuses. Controlled for background factors associated with thymus size and mortality, small thymus size remained a strong and independent risk factor for mortality (hazard ratio = 0.31; 95% confidence interval = 0.18 to 0.52).

CONCLUSIONS

Small thymus size at age 6 months is a strong risk factor for mortality. To prevent unnecessary deaths, it is important to identify preventable factors predisposing to small thymus size.

Antiinfective properties of human milk

The unfavorable effects of neonatal immunodeficiency are limited by some naturally occurring compensatory mechanisms, such as the introduction of protective and immunological components of human milk in the infant. Breast-feeding maintains the maternal-fetal immunological link after birth, may favor the transmission of immunocompetence from the mother to her infant, and is considered an important contributory factor to the neonatal immune defense system during a delicate and crucial period for immune development. Several studies have reported that breast-feeding, because of the antimicrobial activity against several viruses, bacteria, and protozoa, may reduce the incidence of infection in infants. The protection from infections may be ensured either passively by factors with antiinfective, hormonal, enzymatic, trophic, and bioactive activity present in breast milk, or through a modulator effect on the neonatal immune system exerted by cells, cytokines, and other immune agents in human milk.

Undernutrition, infection and immune function

Undernutrition and infection are the major causes of morbidity and mortality in the developing world. These two problems are interrelated. Undernutrition compromises barrier function, allowing easier access by pathogens, and compromises immune function, decreasing the ability of the host to eliminate pathogens once they enter the body. Thus, malnutrition predisposes to infections. Infections can alter nutritional status mediated by changes in dietary intake, absorption and nutrient requirements and losses of endogenous nutrients. Thus, the presence of infections can contribute to the malnourished state. The global burden of malnutrition and infectious disease is immense, especially amongst children. Childhood infections impair growth and development. There is a role for breast-feeding in protection against infections. Key nutrients required for an efficient immune response include vitamin A, Fe, Zn and Cu. There is some evidence that provision of the first three of these nutrients does improve immune function in undernourished children and can reduce the morbidity and mortality of some infectious diseases including measles, diarrhoeal disease and upper and lower respiratory tract infections. Not all studies, however, show benefit of single nutrient supplementation and this might be because the subjects studied have multiple nutrient deficiencies. The situation regarding Fe supplementation is particularly complex. In addition to immunization programmes and improvement of nutrient status, there are important roles for maternal education, improved hygiene and sanitation and increased supply of quality water in the eradication of infectious diseases.

Reduced thymic size and numbers of splenic CD4+ and CD8+ cells in artificially reared mouse pups

The effect of early nutrition on the development of the immune tissue and T cells of mouse pups was examined. Newborn mice were divided into three experimental groups: mother-reared (MR) pups, pups that were fed on a milk substitute from the first day (AR-0), and the third day (AR-2), using a hand-feeding system. The average thymic size of the AR-2 pups was respectively significantly larger and smaller than that of the AR-0 and MR pups. In contrast, the splenic sizes of the AR-0 and AR-2 pups were greater than that of the MR pups. The numbers of CD4+CD8- and CD4-CD8+ cells in the spleen of the MR pups were significantly higher than those in the AR-0 pups. These results indicate that early nutrition affected the sizes of the thymus and spleen and the composition of CD4+CD8- or CD4-CD8+ T cells in the spleen.

Atopic eczema. What has caused the epidemic in industrialised countries and can early intervention modify the natural history of atopic eczema?

Atopic eczema (AE) has a lifetime prevalence of between 15 and 20% in industrialized countries, but a very low prevalence in rural Africa. The 'atopic eczema epidemic' has developed in industrialized countries within the last four decades. The disease has a strong genetic influence, so environmental factors must be responsible for the dramatic increase in disease prevalence. It is therefore fair to consider what interventions may change its prevalence. In this article, several factors are considered: the increased number of doctors in industrialized countries, the development of drugs like topical steroids and emollients, the 'demanding parents' and 'old mother' syndromes, introduction of vaccination programmes, allergen exposure, breastfeeding and the possible beneficial effects of probiotics. In 90% of children with AE, onset is before the age of 5. Its course runs over years. Approximately two out of three outgrow the disease between 7 and 12 years of age. Although its cause is unknown, type I allergic reactions are common and allergen avoidance has been attempted in many studies as a preventive measure in atopic dermatitis. However, results are rather disappointing. The use of probiotics, i.e. daily intake of Lactobacillus, has proven effective in preventing, or at least delaying, the development of atopic eczema. So has breastfeeding, although some studies cannot confirm its beneficial effect. Therapeutic interventions using antihistamines, desensitisation and control of skin inflammation using topical steroids have not proven successful in shortening the course of atopic eczema, although controlled studies are lacking. The use of emollients has, however, a documented effect in up to one of three children with mild atopic eczema. It will be interesting to observe if the new topical immuno-modulators, tacrolimus and pimecrolimus, may be able to shorten the natural course of the disease.

Effect of a fermented formula on thymus size and stool pH in healthy term infants

To investigate the effects of fermented formula (FF) with Bifidobacterium breve C50 and Streptococcus thermophilus 065 on thymus size and stool pH of healthy term infants, ultrasound examinations and evaluations of thymus sizes and thymus indices (TI) and measurements of stool pH were performed in the same 90 term neonates on the 3rd d of life and on the 1st, 2nd, 3rd, and 4th mo of life. Thirty newborns were exclusively breast-fed while the remaining 60 were randomly assigned to receive either a FF or a standard formula (SF). The fecal pH of the breast-fed group was lower than the SF group (p < 0.05), although it was similar to that of the FF group on the third postnatal day, persisting for the entire 4 mo of the study. The difference in TI was statistically significant over repeated measurements among the groups. The FF infants showed a TI similar to the breast-fed newborns. Probiotic fermentation products have effects comparable to those of the bacteria composing the intestinal microflora supporting the idea that intestinal bacterial balance plays an important role in improving host immune responses.