Stool biomarkers as measures of enteric pathogen infection in infants from Addis Ababa informal settlements

Abstract

Frequent enteric infections in children may be an important cause of growth faltering; however, we do not fully understand the mechanisms by which pathogen infections and the physiological responses to these infections result in poorer growth. Commonly used protein fecal biomarkers (anti-alpha trypsin, neopterin, and myeloperoxidase) provide broad immunological information on an inflammatory response; however, they do not provide information on non-immune processes (e.g., gut integrity) that may be important indicators of chronic end states such as environmental enteric dysfunction (EED). To explore how additional biomarkers will better inform which physiological pathways (both immune and non-immune) are impacted by pathogen exposure we added to the traditional panel of 3 protein fecal biomarkers 4 novel fecal mRNA transcript biomarkers (sucrase isomaltase, caudal homeobox 1, S100A8, and mucin 12) and analyzed stool samples from infants living in informal settlements in Addis Ababa, Ethiopia. To test how this expanded biomarker panel captures distinct pathogen exposure processes we used two different scoring systems. First, we used a theory-based approach to assign each biomarker to specific physiological attributes based on prior understanding of each biomarker. Second, we used data reduction methods to categorize biomarkers and then assign physiological attributes to those categories. We used linear models to examine the association between the derived biomarker scores (based on mRNA and protein levels) and stool pathogen gene counts to determine pathogen specific effects on gut physiology and immune responses. Inflammation scores were positively associated with Shigella and enteropathogenic E.Coli (EPEC) infection, while gut integrity scores were negatively associated with Shigella, EPEC and, shigatoxigenic E.coli (STEC) infection. Our expanded panel of biomarkers hold promise as tools to measure systemic outcomes of enteric pathogen infection. mRNA biomarkers complement established protein biomarkers by providing important cell-specific physiological and immunological consequences of pathogen carriage that can lead to chronic end states such as EED.

Multiscalar Evaluation of the Water Distribution System and Diarrheal Disease Risk in Addis Ababa, Ethiopia

“…28 For stool collection, 12 households from each community were randomly selected from the large study sample and asked to provide stool samples. 28 Of the 144 targeted, 136 agreed to participate in this substudy. 28 The collection containers were picked up in the late afternoon and stored at 4 °C prior to processing the following day.…”

“…28 Of the 144 targeted, 136 agreed to participate in this substudy. 28 The collection containers were picked up in the late afternoon and stored at 4 °C prior to processing the following day.…”

“…If more than 5% of rerun samples had CVs higher than 15%, the entire 96-well plate from which the samples were selected from was rerun. 28 Data from the ddPCR analysis is deposited in Dryad under the unique digital object identifier (DOI): doi:10.5061/dryad.7pvmcvdwq. 34 Survey Analysis.…”

“…28 Data from the ddPCR analysis is deposited in Dryad under the unique digital object identifier (DOI): doi:10.5061/dryad.7pvmcvdwq. 34 Survey Analysis. The two outcomes for the survey analysis were two-week diarrheal prevalence and pathogen diversity.…”

“…Within each community, health extension workers identified all households with infants aged 6–23 months and compiled them into a list. Every second or third household was then systematically selected …”