Understanding the role of the gut in undernutrition: what can technology tell us?

Abstract

Gut function remains largely underinvestigated in undernutrition, despite its critical role in essential nutrient digestion, absorption and assimilation. In areas of high enteropathogen burden, alterations in gut barrier function and subsequent inflammatory effects are observable but remain poorly characterised. Environmental enteropathy (EE)—a condition that affects both gut morphology and function and is characterised by blunted villi, inflammation and increased permeability—is thought to play a role in impaired linear growth (stunting) and severe acute malnutrition. However, the lack of tools to quantitatively characterise gut functional capacity has hampered both our understanding of gut pathogenesis in undernutrition and evaluation of gut-targeted therapies to accelerate nutritional recovery. Here we survey the technology landscape for potential solutions to improve assessment of gut function, focussing on devices that could be deployed at point-of-care in low-income and middle-income countries (LMICs). We assess the potential for technological innovation to assess gut morphology, function, barrier integrity and immune response in undernutrition, and highlight the approaches that are currently most suitable for deployment and development. This article focuses on EE and undernutrition in LMICs, but many of these technologies may also become useful in monitoring of other gut pathologies.

Transcutaneous fluorescence spectroscopy: development and characterization of a compact, portable, and fiber-optic sensor

“…These disadvantages-in conjunction with the lack of understanding of the role of the gut in the above conditions and diseases-demonstrate the need for noninvasive and reliable diagnostic tools to provide improved assessment and monitoring of intestinal permeability (and other aspects of gut function). [7][8][9] Recent clinical and preclinical studies have demonstrated that transcutaneous "through-theskin" fluorescence spectroscopy of orally ingested fluorescent contrast agents has the potential for noninvasive monitoring of gut permeability and other GI functions. [10][11][12][13][14][15] This approach entails subjects receiving an oral dose of a fluorescent contrast agent and a fluorescence sensing probe being placed on the skin to detect the permeation of that agent from the gut into the blood stream.…”

A compact fluorescence sensor for low-cost non-invasive monitoring of gut permeability in undernutrition

“…Furthermore, the specialized facilities required to perform the above-mentioned techniques and to analyze the collected samples are often unavailable in low-and middle-income countries (LMICs). As a result, improved diagnostic tools that provide noninvasive and reliable measurements of intestinal permeability (and other aspects of gut function) have the potential to introduce considerable clinical benefits [5,6].…”

Protein status in relation to linear growth faltering and environmental enteropathy

“…To emphasize the importance of environmental enteropathy, the adverse functional impact (local or systemic) of environmental enteropathy, termed as environmental enteric dysfunction (EED), needs to be measured or identified. Although multiple domains of EED have been associated with biomarkers or functional tests of function [2], biomarkers and tests lack consistency and repeatability in different settings and the relationship to growth failure is uncertain [3]. This points towards considerable variation in EED phenotype and underlines the difficulty in defining EED without biopsies.…”