Validation of the Micronutrient and Environmental Enteric Dysfunction Assessment Tool and evaluation of biomarker risk factors for growth faltering and vaccine failure in young Malian children

Abstract

Environmental enteric dysfunction (EED) is an intestinal disorder common among children in low-resource settings and is associated with increased risk of growth stunting, cognitive deficits, and reduced oral vaccine immunogenicity. The Micronutrient and EED Assessment Tool (MEEDAT) is a multiplexed immunoassay that measures biomarkers previously associated with child growth faltering and/or oral vaccine immunogenicity: intestinal fatty acid-binding protein (I-FABP), soluble CD14 (sCD14), insulin-like growth factor 1 (IGF-1), and fibroblast growth factor 21 (FGF21). MEEDAT also measures systemic inflammation (α1-acid glycoprotein, C-reactive protein), ferritin, soluble transferrin receptor, retinol binding protein 4, thyroglobulin, and Plasmodium falciparum antigenemia (histidine-rich protein 2). The performance of MEEDAT was compared with commercially available enzyme-linked immunosorbent assays (ELISAs) using 300 specimens from Malian infant clinical trial participants. Regression methods were used to test if MEEDAT biomarkers were associated with seroconversion to meningococcal A conjugate vaccine (MenAV), yellow fever vaccine (YFV), and pentavalent rotavirus vaccine (PRV) after 28 days, or with growth faltering over 12 weeks. The Pearson correlations between the MEEDAT and ELISA results were 0.97, 0.86, 0.80, and 0.97 for serum I-FABP, sCD14, IGF-1, and FGF21, respectively. There were significant associations between I-FABP concentration and the probability of PRV IgG seroconversion and between IGF-1 concentration and the probability of YFV seroconversion. In multivariable models neither association remained significant, however there was a significant negative association between AGP concentration and YFV seroconversion. GLP-2 and sCD14 concentrations were significantly negatively associated with 12-week change in weight-for-age z-score and weight-for-height z-score in multivariable models. MEEDAT performed well in comparison to commercially-available ELISAs for the measurement of four analytes for EED and growth hormone resistance. Adoption of MEEDAT in low-resource settings could help accelerate the identification of interventions that prevent or treat child stunting and interventions that boost the immunogenicity of child vaccinations.

Fig 1. The 11-plex Micronutrient and EED Assessment Tool.

(A) Schematic of placement of assays in each test well. (B) Images of developed signal in wells of a MEEDAT plate, with varying concentration of each analyte. (C) Images of Q-View Imager LS in use.

Fig 2. Study design flow chart: Grey shading denotes specimens tested with MEEDAT and ELISAs, and inclusion in tests of biomarker associations with growth and parenteral vaccine seroconversion (YFV, MenAV). Bold text denotes inclusion in Case-Control study.

Abbreviations: GI, gastrointestinal; PRV, pentavalent rotavirus vaccine. ⁰ includes n = 152 tested with the GLP-2 ELISA. ¹ includes n = 133 tested with the GLP-2 ELISA who did not experience GI symptoms and IgG or IgA titer rise.

Fig 3. Bland-Altman plots comparing MEEDAT to ELISA for I-FABP, sCD14, IGF-1, and FGF21 in 300 pediatric specimens from Mali.

Abbreviations: FGF21, fibroblast growth factor 21; I-FABP, intestinal fatty acid–binding protein; IGF-1, insulin-like growth factor 1; sCD14, soluble cluster of differentiation 14. ⁰ n = 230 in range of the I-FABP ELISA. ¹ n = 298 valid results for the sCD14 ELISA. ² n = 235 in range of the IGF-1 ELISA and MEEDAT. ³ n = 282 in range of the FGF21 ELISA and MEEDAT.