Anti-Ascaris IgE as a Risk Factor for Asthma Symptoms among 5-Year-Old Children in Rural Bangladesh with Even Decreased Ascaris Infection Prevalence.

BACKGROUND: Epidemiological studies have indicated that anti-Ascaris IgE enhances asthma and allergies under specific conditions although the association between them is still controversial. The association of anti-Ascaris IgE with increased asthma symptoms among children from a general population with a mild to moderate Ascaris infection prevalence was investigated. METHODS: A total of 126 children aged 5 years with wheezing during the previous year and 110 children who did not have wheezing were selected randomly from the rural service area of the International Centre for Diarrhoeal Disease Research, Bangladesh. Serum levels of total, anti-Ascaris, anti-Dermatophagoides pteronyssinus, and anti-cockroach IgEs were tested, and their risks for wheezing were analyzed. The wheezing children were then classified by hierarchical cluster analysis to investigate the contribution of anti-Ascaris IgE to wheezing. RESULTS: The anti-Ascaris IgE levels in wheezing and never-wheezing children were 1.07 and 0.65 UA/mL, and it contributed to 11% of wheezing in children. Anti-Ascaris IgE was significantly associated with wheezing (odds ratio [OR] per loge increment: 1.37 [95% CI: 1.01-1.87], p = 0.046). The ORs, which were adjusted for sex, parental asthma, pneumonia history, helminth infections, Haemophilus influenzae type B combination vaccination, antibiotic use during infancy, and total and specific IgE levels, increased even when only children with more specific symptoms of asthma were included in the analysis. Namely, the ORs for wheezing with sleep disturbance, four or more attacks, and wheezing with speech difficulties during the previous 1 year were OR = 1.44/loge increment [95% CI: 1.01-2.07], OR = 1.90/loge increment [95% CI: 1.11-3.25], and OR = 1.78/loge increment [95% CI: 1.01-3.14], respectively. CONCLUSIONS: The anti-Ascaris IgE levels in wheezing and never-wheezing children in the current study significantly decreased concurrently with Ascaris infection prevalence compared with their corresponding values in 2001. The contribution of anti-Ascaris IgE to wheezing also dropped from 26% in 2001 to 11% in the current study. Despite significant decreases in the levels and the seroprevalence and its contribution to wheezing, anti-Ascaris IgE remained significantly associated with increased risk of wheezing. Anti-Ascaris IgE significantly increased the risk of wheezing in a general population with a mild to moderate Ascaris infection prevalence, suggesting robustness as a risk factor and a possible dose-response relationship.

Risk factors for delay in starting age-appropriate vaccinations among infants in urban slums of Bangladesh.

Age-appropriate vaccination is crucial for infants, protecting them from vaccine-preventable diseases. Delaying in starting initial immunization may result in incomplete or non-vaccination in early life. However, limited vaccine coverage data are available regarding the starting age of vaccination. In this study, we determined the factors associated with the delay in infant immunization. We carried out a cross-sectional study at three maternal-child health clinics in Dhaka city. Mothers visited these clinics for their infant immunization were surveyed with structured questionnaires. A multivariate logistic regression model was used to estimate the significant influencing factors on untimely vaccination. A total of 548 mother-infant pairs were surveyed. 46.5% of mothers did not receive Tetanus (TT) vaccines, and mothers who had a previous pregnancy were less likely to receive TT-vaccine (p < .01). 41.2% of infants did not receive BCG vaccines within 1-week of birth. Mothers working outside the home showed a negative impact on BCG vaccination (p < .05). Among the infants' born in-clinic facilities, 39% were BCG unvaccinated, and 69% had c-section delivery. The median age of infants for starting vaccination was 6.57 wks (95% CI: 6.43-7.14); however, 17.3% infants received vaccination at ≥8 wks of age. Mother's schooling-years and infant normal body-weight positively associated with vaccination at <8 wks, whereas sickness after birth increased the age to start vaccination program recommended at 6 wks. Our analysis suggests the need for specific interventions based on potential maternal determinants, such as educating mothers about the timing and the importance of infant immunization, and addressing programmatic barriers to timely vaccination among infants in Bangladesh.

Impact of Haemophilus influenzae type b combination vaccination on asthma symptoms and pneumonia in 5-year-old children in rural Bangladesh: a longitudinal study and comparison with a previous cross-sectional study.

BACKGROUND: Although the prevalence of bronchial asthma has been increasing worldwide since the 1970's, the prevalence among 5-year-old children was significantly lower in 2016 than in 2001 in rural Bangladesh. We aimed to determine whether the Haemophilus influenzae type b (Hib) combination vaccination (without booster) started in 2009 contributed to this decrease. METHODS: A case-control study was conducted among 1658 randomly selected 5-year-old children from Matlab, Bangladesh. Data on wheezing were collected using the International Study of Asthma and Allergies in Childhood questionnaire. The vaccination data were collected from the records of the Matlab Health and Demographic Surveillance System, while data on pneumonia were obtained from the clinical records of Matlab Hospital. Adjusted odds ratios (aORs) were calculated for the risk for wheezing. The reduction rate was calculated to determine the impact of the vaccination on pneumonia history between the present study and our previous study conducted in 2001 by using the following formula: (percentage of pneumonia cases in 2001 - percentage of pneumonia cases in 2016)/(percentage of pneumonia cases in 2001) times 100 (%). RESULTS: Hib combination vaccination was a protecting factor against wheezing (aOR: 0.50; p = 0.010), while pneumonia at 1, 2, 3-4 years of age were risk factors for wheezing (aOR: 2.86, 3.19, 2.86; p = 0.046, 0.030, 0.030, respectively). The history of pneumonia was significantly lower in the 2016 study participants than those in 2001 both in the overall cohort and the wheezing group (paired t-test: p = 0.012, p < 0.001, respectively). Whereas the history of pneumonia decreased when the children grew older in the 2001 overall cohort, it peaked at the age of 2 years in 2016 wheezing group. The reduction rate decreased when children grew older in both the overall cohort and the wheezing group, however, it decreased faster in the wheezing group. CONCLUSIONS: Hib combination vaccination was a protective factor against wheezing in 0-year-old children. However, the effects of vaccination might have attenuated at the ages of 1-4 years, because no booster dose was administered. The addition of a booster dose might further decrease the prevalence of asthma and wheezing.

Concurrent decreases in the prevalence of wheezing and Ascaris infection among 5-year-old children in rural Bangladesh and their regulatory T cell immunity after the implementation of a national deworming program.

INTRODUCTION: Epidemiological research on the prevalence of asthma and helminthic infections in various countries has led to the hypothesis that helminthic infections protect against asthma by suppressing the host's immune response. This study was conducted to elucidate whether decreased Ascaris infection following a national deworming program was associated with increased recurrent wheezing among rural Bangladeshi children and to test their anti-inflammatory immunity. METHODS: This nested case-control study was conducted from December 2015 to October 2016 in the rural service area of the International Centre for Diarrhoeal Disease Research, Bangladesh. Of the 1800 5-year old children randomly selected for the study, informed consent was obtained from the guardians of 1658 children. Data were collected using a semistructured questionnaire adopted from the International Study of Asthma and Allergies in Childhood and blood samples for the analysis of regulatory T (Treg) cell immune responses and the balance between Th1 and Th2 immunity in Ascaris infections. RESULTS: A total of 145 children were found to have wheezing, yielding a prevalence rate of 8.7%, which was significantly lower than the rate found in 2001 (16.2%, P < .001); Ascaris infection also decreased from 2001 to 2016. The 127 wheezing children who agreed to participate further were compared to 114 randomly selected never-wheezing children. Wheezing had a significant positive association with antibiotic use, history of pneumonia, parents' history of asthma, and Ascaris infection; children with Ascaris infection were twice as likely to have wheezing (adjusted odds ratio = 2.31, P = .053). Flow cytometry found no significant differences in the rates of Th1, Th2, and CD4 + CD25 + CD127low cells by the wheezing group. CONCLUSIONS: Ascaris infection had a positive rather than a negative association with wheezing and the rates of wheezing and Ascaris infections both decreased from 2001 to 2016. These findings undermines the hypothesis that such infections provide protection against asthma.

Comparisons of the effect of naturally acquired maternal pertussis antibodies and antenatal vaccination induced maternal tetanus antibodies on infant's antibody secreting lymphocyte responses and circulating plasma antibody levels.

The goal of this study was to explore the effects of trans-placental tetanus toxoid (TT) and pertussis (PT) antibodies on an infant's response to vaccination in the context of antenatal immunization with tetanus but not with pertussis. 38 mothers received a single dose of TT vaccine during pregnancy. Infants received tetanus and pertussis vaccines at 6, 10 and 14 wk of age. TT and PT anti-IgG secretion by infant lymphocytes was measured at 15 wk. Plasma antibodies were measured at 6 wk (pre-vaccination), 15 wk and 1 y of age. Prior to vaccination, TT and PT antibody were detected in 94.6% and 15.2% of infants. At 15 wk anti-TT-IgG and anti-PT-IgG in plasma was increased by 7-9 fold over pre-vaccination levels, while at 1 y plasma anti-TT-IgG was decreased by approximately 5-fold from the peak and had returned to near the pre-vaccination level. At 1 y plasma anti-PT-IgG was decreased by 2-fold 1 yfrom the 15 wk level. However, 89.5% and 82.3% of infants at 1 y had protective levels of anti-TT and anti-PT IgG, respectively. Pre-vaccination plasma IgG levels were associated with lower vaccine-specific IgG secretion by infant lymphocytes at 15 wk (p < 0.10). This apparent inhibition was seen for anti-TT-IgG at both 15 wk (p < 0.05) and t 1 y (p < 0.10) of age. In summary, we report an apparent inhibitory effect of passively derived maternal antibody on an infants' own antibody response to the same vaccine. However, since the cut-off values for protective titers are low, infants had protective antibody levels throughout infancy.

Maternal zinc supplementation improves hepatitis B antibody responses in infants but decreases plasma zinc level.

PURPOSE: The World Health Report identifies zinc deficiency as one of the major causes of disease in developing countries, and infants are at particular risk. We aimed to investigate the effect of maternal zinc supplementation on the infant's immune function in a population at risk of deficiency. METHODS: In a randomized, double-blind placebo-controlled trial, mothers were supplemented either with 20 mg/day of elemental zinc (n = 20) or placebo (n = 19) at the beginning of second trimester, which continued until 6 months postpartum. Indicators of the infants' immune function measured included interleukin (IL)-7, thymic size and response to hepatitis B vaccination. RESULTS: Infants born from mothers receiving zinc supplements during pregnancy and postpartum had significantly lower plasma zinc (p < 0.05) but marginally higher IL-7 and antibody responses to hepatitis B vaccination (p < 0.10) than infants born from mothers not receiving zinc. Maternal zinc supplementation showed no negative impact on copper status of mothers or their infants. Maternal zinc supplementation did not influence infant thymic size, but cord blood IL-7 was found positively associated with thymus size at 1 month of age (r = 0.392) and with hepatitis B vaccine response at 6 months of age (r = 0.386). CONCLUSION: Prenatal and postnatal zinc supplementation marginally improved T cell-dependent antibody responses in infants along with IL-7, a cytokine involved in human T cell development and maintaining homeostasis.

The effect of postpartum vitamin A supplementation on breast milk immune regulators and infant immune functions: study protocol of a randomized, controlled trial.

BACKGROUND: Because of limited impact on infant morbidity, mortality, and vitamin A status, the new guideline of the World Health Organization (WHO) does not recommend postpartum vitamin A supplementation (VAS) as a public health intervention in developing countries. However, breast milk contains numerous immune-protective components that are important for infant immune development, and several of these components are regulated by vitamin A. METHODS/DESIGN: Postpartum women are being enrolled within 3 days (d) of delivery at a maternity clinic located in a slum area of Dhaka city and randomized to one of four postpartum VAS regimens (32/group, total 128). The regimens are as follows: Group 1: 200,000 IU VAS at <3 d and placebo at 6 weeks postpartum; Group 2: placebo at <3 d and 200,000 IU VAS at 6 weeks postpartum; Group 3: 200,000 IU VAS, both at <3 d and 6 weeks postpartum; Group 4: placebo, both at <3 d and 6 weeks postpartum. Breast milk samples at <3 d (before supplementation) and 4 months postpartum will be used to measure vitamin A and bioactive compounds. Infant blood samples at 2 and 4 months of age will be used to measure vitamin A, as well as innate and vaccine-specific immune responses. Dietary, anthropometric, and morbidity data are also being collected. DISCUSSION: This is the first placebo-controlled randomized clinical trial of postnatal vitamin A supplementation to investigate the key bioactive compounds in breast milk, important for infant immunity, in relation to dose and time point of postpartum supplementation and whether such maternal supplementation improves infant immune status during the critical period of early infancy. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02043223 , 5 December 2013.

On birth single dose live attenuated OPV and BCG vaccination induces gut cathelicidin LL37 responses at 6 week of age: a natural experiment.

In a cross sectional study, we show that infants who received single dose of live attenuated OPV and BCG vaccines within 48h of birth, have higher excretion of human cathelicidin LL37 (p<0.05) in stool at 6wk of age. This response remained unchanged in multivariate analysis after adjusting for sex, mode of delivery, infant age, mother age birth weight and breast milk feeding pattern. This analysis also reveals that irrespective of vaccination, girl infants have higher human-beta-defencin2 (HBD2) and exclusively breastfed infants have higher total and anti-polio specific IgA to all three subtypes in stool (p<0.05). However, vaccination induces anti-polio IgA responses only to infants who are exclusively breastfed. Thus on-birth live attenuated vaccination may provide non-specific beneficial effect against infections while exclusive breastfeeding enhance protection by boosting vaccine induced IgA. The result also suggests that in polio endemic area, exclusive breastfeeding may be sufficient for mucosal anti-polio responses during early infancy.

The effect of newborn vitamin A supplementation on infant immune functions: trial design, interventions, and baseline data.

In recent years, neonatal vitamin A supplementation is considered as an essential infant-survival intervention but the evidence is not conclusive. This randomized controlled clinical trial was conducted to evaluate the effect of vitamin A on immune competence in early infancy. Results would provide a mechanistic basis for understanding the effect of this intervention on infant survival. Within 2 days of birth, infants born at one maternity clinic located in a poor slum area of Dhaka city were supplemented with either 50,000 IU vitamin A or placebo. Live attenuated oral polio vaccine (OPV) and BCG vaccine were provided after supplementation. Infants also receive diphtheria, pertussis, tetanus (TT), hepatitis B (HBV) and Haemophilus influenzae B vaccines (pentavalent combination) along with OPV at 6, 10 and 14 weeks of age. Infant thymus size, anthropometry, feeding practice and morbidity data were collected at regular interval. Infant blood samples were collected to determine T-cell-receptor excision circle (TREC), total, naïve and memory T cells and mucosal targeting lymphocytes including Treg cells. TT-, HBV-, BCG- and OPV-specific T cell blastogenic, cytokine and plasma cell antibody responses were also measured. In 16 mo enrollment period, 306 newborns, equal number of boys and girls, were enrolled. ~95% completed the 4-month follow-up period. Baseline characteristics are presented here. Anthropometry and immune assays with fresh blood samples were completed immediately while stored samples were analyzed in single batches at the end of the trial. Connecting different aspects of immunological data in early infancy will help elucidate immune competence for protecting infection. Trial registration ClinicalTrials.gov: NCT01583972.

Antibody avidity in humoral immune responses in Bangladeshi children and adults following administration of an oral killed cholera vaccine.

Antibody avidity for antigens following disease or vaccination increases with affinity maturation and somatic hypermutation. In this study, we followed children and adults in Bangladesh for 1 year following oral cholera vaccination and measured the avidity of antibodies to the T cell-dependent antigen cholera toxin B subunit (CTB) and the T cell-independent antigen lipopolysaccharide (LPS) in comparison with responses in other immunological measurements. Children produced CTB-specific IgG and IgA antibodies of high avidity following vaccination, which persisted for several months; the magnitudes of responses were comparable to those seen in adult vaccinees. The avidity of LPS-specific IgG and IgA antibodies in vaccinees increased significantly shortly after the second dose of vaccine but waned rapidly to baseline levels thereafter. CTB-specific memory B cells were present for only a short time following vaccination, and we did not find significant memory B cell responses to LPS in any age group. For older children, there was a significant correlation between CTB-specific memory T cell responses after the second dose of vaccine and CTB-specific IgG antibody avidity indices over the subsequent year. These findings suggest that vaccination induces a longer-lasting increase in the avidity of antibodies to a T cell-dependent antigen than is measured by a memory B cell response to that antigen and that early memory T cell responses correlate well with the subsequent development of higher-avidity antibodies.

Study of avidity of antigen-specific antibody as a means of understanding development of long-term immunological memory after Vibrio cholerae O1 infection.

The avidity of antibodies to specific antigens and the relationship of avidity to memory B cell responses to these antigens have not been studied in patients with cholera or those receiving oral cholera vaccines. We measured the avidity of antibodies to cholera toxin B subunit (CTB) and Vibrio cholerae O1 lipopolysaccharide (LPS) in Bangladeshi adult cholera patients (n = 30), as well as vaccinees (n = 30) after administration of two doses of a killed oral cholera vaccine. We assessed antibody and memory B cell responses at the acute stage in patients or prior to vaccination in vaccinees and then in follow-up over a year. Both patients and vaccinees mounted CTB-specific IgG and IgA antibodies of high avidity. Patients showed longer persistence of these antibodies than vaccinees, with persistence lasting in patients up to day 270 to 360. The avidity of LPS-specific IgG and IgA antibodies in patients remained elevated up to 180 days of follow-up. Vaccinees mounted highly avid LPS-specific antibodies at day 17 (3 days after the second dose of vaccine), but the avidity waned rapidly to baseline by 30 days. We examined the correlation between antigen-specific memory B cell responses and avidity indices for both antigens. We found that numbers of CTB- and LPS-specific memory B cells significantly correlated with the avidity indices of the corresponding antibodies (P < 0.05; Spearman's ρ = 0.28 to 0.45). These findings suggest that antibody avidity after infection and immunization is a good correlate of the development and maintenance of memory B cell responses to Vibrio cholerae O1 antigens.

Differential host immune responses to epidemic and endemic strains of Shigella dysenteriae type I.

Shigella dysenteriae type 1 causes devastating epidemics in developing countries with high case-fatality rates in all age-groups. The aim of the study was to compare host immune responses to epidemic (T2218) and endemic strains of S. dysenteriae type 1. Shigellacidal activity of serum from rabbits immunized with epidemic or endemic strains, S. dysenteriae type 1-infected patients, and healthy adult controls from Shigella-endemic and non-endemic regions was measured. Immunogenic cross-reactivity of antibodies against Shigella antigens was evaluated by Western blot analysis. Oxidative burst and phagocytic responses of monocytes and neutrophils to selected S. dysenteriae type 1 strains were assessed by flow cytometry. Rabbit antisera against epidemic strain were less effective in killing heterologous bacteria compared to endemic antisera (p=0.0002). Patients showed an increased serum shigellacidal response after two weeks of onset of diarrhoea compared to the acute stage (3-4 days after onset) against their respective homologous strains; the response against T2218 and heterologous endemic S. dysenteriae type 1 strains was not significant. The serum shigellacidal response against all the S. dysenteriae type 1 strains was similar among healthy controls from endemic and non-endemic regions and was comparable with the acute stage response by patients. Compared to endemic strains of S. dysenteriae type 1, T2218 was significantly resistant to phagocytosis by both monocytes and neutrophils. No obvious differences were obtained in the induction of oxidative burst activity and cathelicidin-mediated killing. Cross-reactivity of antibody against antigens present in the epidemic and endemic strains showed some differences in protein/peptide complexity and intensity by Western blot analysis. In summary, epidemic T2218 strain was more resistant to antibody-mediated defenses, namely phagocytosis and shigellacidal activity, compared to endemic S. dysenteriae type 1 strains. Part of this variation may be attributed to the differential complexity of protein/peptide antigens.

Zinc influences innate immune responses in children with enterotoxigenic Escherichia coli-induced diarrhea.

Information is limited on the effect of zinc on immune responses in children with diarrhea due to enterotoxigenic Escherichia coli (ETEC), the most common bacterial pathogen in children. We studied the immunological effect of zinc treatment (20 mg/d) and supplementation (10 mg/d) in children with diarrhea due to ETEC. A total of 148 children aged 6-24 mo were followed up for 9 mo after a 10-d zinc treatment (ZT; n = 74) or a 10-d zinc treatment plus 3-mo supplementation (ZT+S; n = 74), as well as 50 children with ETEC-induced diarrhea that were not treated with zinc (UT). Fifty control children (HC) of the same age group from the same location were also studied. Serum zinc concentrations were higher in both the ZT (P < 0.001) and ZT+S groups (P < 0.001) than in the UT group but did not differ from the HC group. We found higher serum complement C3 immediately after zinc administration in both ZT (P < 0.001) and ZT+S (P < 0.001) groups than in the UT group. Phagocytic activity in children in both ZT (P < 0.01) and ZT+S (P < 0.01) groups was greater than in the UT group. However, oxidative burst capacity was lower in zinc-receiving groups (ZT, P < 0.001 and ZT+S, P < 0.001) than in the UT group. The naïve:memory T cell ratio in both ZT (P < 0.05) and ZT+S (P < 0.01) groups was higher than in the UT group from d 2 to 15. Increased responses, including complement C3, phagocytic activity, and changes in T cell phenotypes, suggest that zinc administration enhances innate immunity against ETEC infection in children.

Low birth weight is associated with altered immune function in rural Bangladeshi children: a birth cohort study.

BACKGROUND: Low birth weight is generally an outcome of a fetal insult or nutritional insufficiency. Recent studies have shown that such exposure early in life may have long-term implications for later immunocompetence and susceptibility to infectious diseases. OBJECTIVE: We aimed to investigate the effect of birth weight on immune function in preschool-age children. DESIGN: A birth cohort cross-sectional study was conducted in children (n = 132) aged 60.8 +/- 0.32 mo who were born in Matlab, a rural area of Bangladesh, and whose weight and length were measured within 72 h of birth. The outcome measures were thymopoiesis, T cell turnover, acute phase response, and percentage of lymphocytes. RESULTS: Children born with low birth weight (<2500 g; LBW group, n = 66) had significantly higher concentrations of T cell receptor excision circles in peripheral blood mononuclear cells-a biomarker for thymopoiesis-and significantly higher serum bactericidal activity and C-reactive protein concentrations than did children born with normal birth weight (>or=2500 g; NBW group, n = 66) (P < 0.05 for both). The LBW group children had significantly lower concentrations of interleukin 7 in plasma (P = 0.02), shorter telomere length in peripheral blood mononuclear cells (P = 0.02), and a lower percentage of CD3 T cells (P = 0.06) than did the NBW group children. CONCLUSIONS: Greater peripheral T cell turnover (shorter telomeres and lower CD3 concentrations) due to immune activation (elevated C-reactive protein concentrations and bactericidal activity) may have resulted in a greater need for replenishment from the thymus (higher T cell receptor excision circles); these events may cause lower immune functional reserve in preschool-age children born with LBW. Thus, LBW has implications for immunocompetence and increased vulnerability to infectious diseases in later life.