Serum anti-flagellin and anti-lipopolysaccharide immunoglobulins as predictors of linear growth faltering in Pakistani infants at risk for environmental enteric dysfunction.
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ABSTRACT: Environmental Enteric Dysfunction (EED) in children from low-income countries has been linked to linear growth declines. There is a critical need to identify sensitive and early EED biomarkers.Determine whether levels of antibodies against bacterial components flagellin (flic) and lipopolysaccharide (LPS) predict poor growth.In a prospective birth cohort of 380 children in rural Pakistan blood and stool samples were obtained at ages 6 and 9 months. Linear mixed effects models were used to examine longitudinal associations between quartiles of anti-flic and anti-LPS antibodies and changes in LAZ, WAZ and WLZ scores. Spearman's correlations were measured between anti-flic and anti-LPS immunoglobulins with measures of systemic/enteric inflammation and intestinal regeneration.Anti-LPS IgA correlated significantly with CRP, AGP and Reg1 serum at 6mo and with MPO at 9mo. In multivariate analysis at 6mo of age, higher anti-LPS IgA levels predicted greater declines in LAZ scores over subsequent 18mo (comparing highest to lowest quartile, β (SE) change in LAZ score/year = -0.313 (0.125), p-value = 0.013). Anti-flic Ig A in the two highest quartiles measured at 9mo of age had declines in LAZ of -0.269 (0.126), p = 0.033; and -0.306 (0.129), p = 0.018 respectively, during the subsequent 18mo of life, compared to those in the lowest quartile of anti-flic IgA.Elevated anti-flic IgA and anti-LPS IgA antibodies at 6 and 9mo, predict declines in linear growth. Systemic and enteric inflammation correlated with anti-LPS IgA provides mechanistic considerations for potential future interventions.
Project description:BackgroundThe underperformance of oral vaccines in children of low- and middle-income countries is partly attributable to underlying environmental enteric dysfunction (EED).MethodologyWe conducted a longitudinal, community-based study to evaluate the association of oral rotavirus vaccine (Rotarix®) seroconversion with growth anthropometrics, EED biomarkers and intestinal enteropathogens in Pakistani infants. Children were enrolled between three to six months of their age based on their nutritional status. We measured serum anti-rotavirus immunoglobulin A (IgA) at enrollment and nine months of age with EED biomarkers and intestinal enteropathogens.ResultsA total of 391 infants received two doses of rotavirus (RV) vaccine. 331/391 provided paired blood samples. Of these 331 children, 45% seroconverted at 9 months of age, 35% did not seroconvert and 20% were seropositive at baseline. Non-seroconverted children were more likely to be stunted, wasted and underweight at enrollment. In univariate analysis, insulin-like growth factor (IGF) concentration at 6 months were higher in seroconverters, median (25th, 75th percentile): 26.3 (16.5, 43.5) ng/ml vs. 22.5 (13.6, 36.3) ng/ml for non-seroconverters, p-value = 0.024. At nine months, fecal myeloperoxidase (MPO) concentrations were significantly lower in seroconverters, 3050(1250, 7587) ng/ml vs. 4623.3 (2189, 11650) ng/ml in non-seroconverted children, p-value = 0.017. In multivariable logistic regression analysis, alpha-1 acid glycoprotein (AGP) and IGF-1 concentrations were positively associated with seroconversion at six months. The presence of sapovirus and rotavirus in fecal samples at the time of rotavirus administration, was associated with non-seroconversion and seroconversion, respectively.ConclusionWe detected high baseline RV seropositivity and impaired RV vaccine immunogenicity in this high-risk group of children. Healthy growth, serum IGF-1 and AGP, and fecal shedding of rotavirus were positively associated with RV IgA seroconversion following immunization, whereas the presence of sapovirus was more common in non-seroconverters.Trial registrationClinical Trials ID: NCT03588013.
Project description:Childhood diarrhea in low-resource settings has been variably linked to linear growth shortfalls. However, the association between etiology-specific diarrhea and growth has not been comprehensively evaluated. We tested diarrheal stools collected from the Performance of Rotavirus and Oral Polio Vaccines in Developing Countries study from 2011 to 2013 in Dhaka, Bangladesh, by quantitative polymerase chain reaction for a broad range of enteropathogens to characterize diarrhea etiology and examine the association between etiology-specific diarrhea and linear growth and systemic inflammation. Pathogen-specific burdens of diarrhea were determined using attributable fractions. Linear regression was used to examine associations of pathogen-specific diarrhea with length-for-age z scores (LAZ) and serum C-reactive protein. There was no relationship between all-cause diarrhea and length at 12 months (change in 12-month LAZ per episode, -0.01, 95% confidence interval (CI): -0.06, 0.03). However, Cryptosporidium (change in 12-month LAZ per attributable episode, -0.23, 95% CI: -0.50, 0.03), Campylobacter jejuni/coli (change of -0.16, 95% CI: -0.32, -0.01), and Shigella/enteroinvasive Escherichia coli diarrhea (change of -0.12, 95% CI: -0.26, 0.03) were associated with linear growth deficits. Diarrhea attributable to C. jejuni/coli and Shigella/enteroinvasive E. coli were associated with elevated C-reactive protein. The association between diarrhea and linear growth appears to be pathogen-specific, reinforcing the need for pathogen-specific interventions.
Project description:BackgroundAntibodies to LPS and flagellin have been described as indirect measures of increased gastrointestinal permeability and may be markers of environmental enteric dysfunction (EED), which is a condition associated with poor child growth.ObjectiveWe assessed whether LPS- and flagellin-specific immunoglobulin (Ig) concentrations were associated with poor growth in young Tanzanian children at risk of EED.DesignBlood samples were obtained from 590 children at 6 wk, 6 mo, and 12 mo of age. Serum LPS- and flagellin-specific Ig concentrations (IgA and IgG) were measured with the use of an ELISA. Growth was measured on a monthly basis for 18 mo.ResultsAnti-LPS and anti-flagellin IgA and IgG concentrations increased over the first year of life and were higher than concentrations (measured at 9 mo of age) in healthy controls. Children with anti-flagellin IgA, anti-LPS IgA, anti-flagellin IgG, and anti-LPS IgG concentrations in the highest quartile at 6 wk of age were 2.02 (95% CI: 1.11, 3.67), 1.84 (95% CI: 1.03, 3.27), 1.94 (95% CI: 1.04, 3.62), and 2.31 (95% CI: 1.25, 4.27) times, respectively, more likely to become underweight (weight-for-age z score <-2) after adjustment for covariates (P-trend < 0.05) than were children with Ig concentrations in the lowest quartile. Children with increased concentrations of anti-flagellin IgA were also more likely to become wasted; however, there was no association between any of the markers and subsequent stunting.ConclusionSerologic measures of increased intestinal permeability to bacterial components are associated with subsequent poor growth and could help identify children who may benefit most from preventive interventions. This trial was registered at clinicaltrials.gov as NCT00421668.
Project description:The associations between enteric pathogenic parasites and growth in infants in São Tomé were explored using a refined anthropometric approach to recognize early growth faltering. A birth cohort study was conducted with follow-up to 24 months of age. Microscopic examination for protozoa and soil-transmitted helminths was performed. Anthropometric assessments included: z-scores for weight-for-length (WLZ), length-for-age (LAZ), weight (WAVZ) and length velocities (LAVZ), length-for-age difference (LAD), and wasting and stunting risk (?-1 SD). Generalized additive mixed effects regression models were used to explore the associations between anthropometric parameters and enteric parasitic infections and cofactors. A total of 475 infants were enrolled, and 282 completed the study. The great majority of infants were asymptomatic. Giardia lamblia was detected in 35.1% of infants in at least one stool sample, helminths in 30.4%, and Cryptosporidium spp. in 14.7%. Giardia lamblia and helminth infections were significantly associated with mean decreases of 0.10 in LAZ and 0.32 in LAD, and of 0.16 in LAZ and 0.48 in LAD, respectively. Cryptosporidium spp. infection was significantly associated with a mean decrease of 0.43 in WAVZ and 0.55 in LAVZ. The underestimated association between subclinical parasitic enteric infections and mild growth faltering in infants should be addressed in public health policies.
Project description:BACKGROUND:Moderate-to-severe diarrhea (MSD) in the first 2?years of life can impair linear growth. We sought to determine risk factors for linear growth faltering and to build a clinical prediction tool to identify children most likely to experience growth faltering following an episode of MSD. METHODS:Using data from the Global Enteric Multicenter Study of children 0-23?months old presenting with MSD in Africa and Asia, we performed log-binomial regression to determine clinical and sociodemographic factors associated with severe linear growth faltering (loss of ??0.5 length-for-age z-score [LAZ]). Linear regression was used to estimate associations with ?LAZ. A clinical prediction tool was developed using backward elimination of potential variables, and Akaike Information Criterion to select the best fit model. RESULTS:Of the 5902 included children, mean age was 10?months and 43.2% were female. Over the 50-90-day follow-up period, 24.2% of children had severe linear growth faltering and the mean ?LAZ over follow-up was -?0.17 (standard deviation [SD] 0.54). After adjustment for age, baseline LAZ, and site, several factors were associated with decline in LAZ: young age, acute malnutrition, hospitalization at presentation, non-dysenteric diarrhea, unimproved sanitation, lower wealth, fever, co-morbidity, or an IMCI danger sign. Compared to children 12-23?months old, those 0-6?months were more likely to experience severe linear growth faltering (adjusted prevalence ratio [aPR] 1.97 [95% CI 1.70, 2.28]), as were children 6-12?months of age (aPR 1.72 [95% CI 1.51, 1.95]). A prediction model that included age, wasting, stunting, presentation with fever, and presentation with an IMCI danger sign had an area under the ROC (AUC) of 0.67 (95% CI 0.64, 0.69). Risk scores ranged from 0 to 37, and a cut-off of 21 maximized sensitivity (60.7%) and specificity (63.5%). CONCLUSION:Younger age, acute malnutrition, MSD severity, and sociodemographic factors were associated with short-term linear growth deterioration following MSD. Data routinely obtained at MSD may be useful to predict children at risk for growth deterioration who would benefit from interventions.
Project description:BackgroundChronic malnutrition, termed stunting, is defined as suboptimal linear growth, affects one third of children in developing countries, and leads to increased mortality and poor developmental outcomes. The causes of childhood stunting are unknown, and strategies to improve growth and related outcomes in children have only had modest impacts. Recent studies have shown that the ecosystem of microbes in the human gut, termed the microbiota, can induce changes in weight. However, the specific changes in the gut microbiota that contribute to growth remain unknown, and no studies have investigated the gut microbiota as a determinant of chronic malnutrition.ResultsWe performed secondary analyses of data from two well-characterized twin cohorts of children from Malawi and Bangladesh to identify bacterial genera associated with linear growth. In a case-control analysis, we used the graphical lasso to estimate covariance network models of gut microbial interactions from relative genus abundances and used network analysis methods to select genera associated with stunting severity. In longitudinal analyses, we determined associations between these selected microbes and linear growth using between-within twin regression models to adjust for confounding and introduce temporality. Reduced microbiota diversity and increased covariance network density were associated with stunting severity, while increased relative abundance of Acidaminococcus sp. was associated with future linear growth deficits.ConclusionsWe show that length growth in children is associated with community-wide changes in the gut microbiota and with the abundance of the bacterial genus, Acidaminococcus. Larger cohorts are needed to confirm these findings and to clarify the mechanisms involved.
Project description:BACKGROUND:HIV-exposed uninfected (HEU) children experience increased mortality compared with their HIV-unexposed uninfected (HUU) peers. It is unclear whether HEU children are also at increased risk for undernutrition, a modifiable risk factor for mortality. METHODS:We conducted a cross-sectional, population-based survey of children <5 years of age in 5 health districts in Botswana. Linear mixed-effects models were used to assess continuous outcomes, and generalized estimating equations were used to estimate relative risks of stunting, wasting, and underweight between HEU (n = 396) and HUU (n = 1109) children. Secondary analyses examined potential mediation by low birth weight. RESULTS:The association between maternal HIV exposure and child stunting varied significantly by child age (P < 0.01). HEU children <1 and ?2 years of age had 1.85 [95% confidence interval (CI): 1.03 to 3.31; P = 0.04] and 1.41 (95% CI: 1.06 to 1.88; P = 0.02) times the risk of stunting compared with HUU children after multivariate adjustment, respectively. During the period of 1-2 years of age, when breastfeeding cessation occurred among HUU children, HUU children had increased risk of stunting compared with HEU children who were predominantly formula fed (relative risk: 1.56; 95% CI: 1.05 to 2.32; P = 0.03). A mediation analysis estimated that 67% of the excess risk of stunting among HEU children ?2 years was attributable to low birth weight (P = 0.02). There was no difference in risk of wasting or underweight. CONCLUSION:HEU children are at increased risk of stunting compared with their HUU peers; however, interventions to increase birth weight may significantly ameliorate this excess risk. Interventions to support optimal growth during weaning are needed for all breast-fed children.
Project description:Noroviruses are enteric pathogens causing significant morbidity, mortality, and economic losses worldwide. Secretory immunoglobulins (sIg) are a first line of mucosal defense against enteric pathogens. They are secreted into the intestinal lumen via the polymeric immunoglobulin receptor (pIgR), where they bind to antigens. However, whether natural sIg protect against norovirus infection remains unknown. To determine if natural sIg alter murine norovirus (MNV) pathogenesis, we infected pIgR knockout (KO) mice, which lack sIg in mucosal secretions. Acute MNV infection was significantly reduced in pIgR KO mice compared to controls, despite increased MNV target cells in the Peyer's patch. Natural sIg did not alter MNV binding to the follicle-associated epithelium (FAE) or crossing of the FAE into the lymphoid follicle. Instead, naive pIgR KO mice had enhanced levels of the antiviral inflammatory molecules interferon gamma (IFN-?) and inducible nitric oxide synthase (iNOS) in the ileum compared to controls. Strikingly, depletion of the intestinal microbiota in pIgR KO and control mice resulted in comparable IFN-? and iNOS levels, as well as MNV infectious titers. IFN-? treatment of wild-type (WT) mice and neutralization of IFN-? in pIgR KO mice modulated MNV titers, implicating the antiviral cytokine in the phenotype. Reduced gastrointestinal infection in pIgR KO mice was also observed with another enteric virus, reovirus. Collectively, our findings suggest that natural sIg are not protective during enteric virus infection, but rather, that sIg promote enteric viral infection through alterations in microbial immune responses.IMPORTANCE Enteric virus, such as norovirus, infections cause significant morbidity and mortality worldwide. However, direct antiviral infection prevention strategies are limited. Blocking host entry and initiation of infection provides an established avenue for intervention. Here, we investigated the role of the polymeric immunoglobulin receptor (pIgR)-secretory immunoglobulin (sIg) cycle during enteric virus infections. The innate immune functions of sIg (agglutination, immune exclusion, neutralization, and expulsion) were not required during control of acute murine norovirus (MNV) infection. Instead, lack of pIgR resulted in increased IFN-? levels, which contributed to reduced MNV titers. Another enteric virus, reovirus, also showed decreased infection in pIgR KO mice. Collectively, our data point to a model in which sIg-mediated microbial sensing promotes norovirus and reovirus infection. These data provide the first evidence of the proviral role of natural sIg during enteric virus infections and provide another example of how intestinal bacterial communities indirectly influence MNV pathogenesis.
Project description:Globally, 149 million children under 5 years of age are estimated to be stunted (length more than 2 standard deviations below international growth standards)1,2. Stunting, a form of linear growth faltering, increases the risk of illness, impaired cognitive development and mortality. Global stunting estimates rely on cross-sectional surveys, which cannot provide direct information about the timing of onset or persistence of growth faltering-a key consideration for defining critical windows to deliver preventive interventions. Here we completed a pooled analysis of longitudinal studies in low- and middle-income countries (n = 32 cohorts, 52,640 children, ages 0-24 months), allowing us to identify the typical age of onset of linear growth faltering and to investigate recurrent faltering in early life. The highest incidence of stunting onset occurred from birth to the age of 3 months, with substantially higher stunting at birth in South Asia. From 0 to 15 months, stunting reversal was rare; children who reversed their stunting status frequently relapsed, and relapse rates were substantially higher among children born stunted. Early onset and low reversal rates suggest that improving children's linear growth will require life course interventions for women of childbearing age and a greater emphasis on interventions for children under 6 months of age.
Project description:Background: Previous studies in the UK and Denmark found no significant association between low socioeconomic status (SES) and weight faltering. However, to our knowledge, there are no studies from other developed countries. We examined the association between parental SES and weight faltering in infants up to 1.5 years of age, and investigated whether the inequalities changed between 2001 and 2010 in Japan. Methods: We used data from two Japanese population-based birth cohorts started in 2001 (n = 34,594) and 2010 (n = 21,189). Parental SES was assessed as household income and parental education when the infant was 6 months old. Weight faltering was defined as the slowest weight gaining in 5% of all children in each cohort. Logistic regression analyses were conducted with adjustment for covariates. The relative index of inequality was used to assess relative impact of parental SES on weight faltering. Results: Infants in the lowest quartile of household income were 1.29 (95% confidence interval [CI]: 1.10, 1.52) and 1.27 (95% CI: 1.03, 1.56) times more likely to experience weight faltering than those in the highest income quartile both in the 2001 and 2010 cohorts, respectively. The relative index of inequality for household income was 1.66 (95% CI: 1.36, 1.96) in 2001 and 1.86 (95% CI: 1.42, 2.31) in 2010. Conclusions: Infants from lower income families have a greater risk of weight faltering in Japan. Additionally, the income-related inequalities in weight faltering did not change between the two cohorts. Social policies to address maldistribution of weight faltering due to household income are needed.