The role of epigenetics in respiratory health in urban populations in low and middle-income countries.

Nicole M Robertson,William Checkley,Bruce Kirenga,Trishul Siddharthan,Christine Ladd-Acosta,Alex Kayongo,Suzanne L Pollard,Jose Gomez Villalobos

doi:10.1017/gheg.2019.7

Abstract

As urbanization increases in low- and middle-income countries (LMICs), urban populations will be increasingly exposed to a range of environmental risk factors for non-communicable diseases. Inadequate living conditions in urban settings may influence mechanisms that regulate gene expression, leading to the development of non-communicable respiratory diseases. We conducted a systematic review of the literature to assess the relationship between respiratory health and epigenetic factors to urban environmental exposures observed in LMICs using MEDLINE, PubMed, EMBASE, and Google Scholar searching a combination of the terms: epigenetics, chronic respiratory diseases (CRDs), lung development, chronic obstructive airway disease, and asthma. A total of 2835 articles were obtained, and 48 articles were included in this review. We found that environmental factors during early development are related to epigenetic effects that may be associated with a higher risk of CRDs. Epigenetic dysregulation of gene expression of the histone deacetylase (HDAC) and histone acetyltransferase gene families was likely involved in lung health of slum dwellers. Respiratory-related environmental exposures influence HDAC function and deoxyribonucleic acid methylation and are important risk factors in the development of CRD. Additional epigenetic research is needed to improve our understanding of associations between environmental exposures and non-communicable respiratory diseases.

Highlights

In 2014, 881 million people in low- and middle-income countries (LMICs) lived in urban slums, and this number is expected to grow on average by 9 million people each year [1, 2]
We aim to focus on the current knowledge of epigenetic markers related to human environmental exposures that affect lung health and relate this to urban residents, but slum dwellers, in LMICs as a measure of the impact of urbanization in chronic illness
Studies that presented results not conducted in LMICs or that could not be applied to LMIC settings were excluded

Summary

Introduction

In 2014, 881 million people in low- and middle-income countries (LMICs) lived in urban slums, and this number is expected to grow on average by 9 million people each year [1, 2]. In sub-Saharan Africa, the United Nations Habitat estimated that a majority of urban populations, at about 56%, live in slums [2, 5]. Urbanization, the migration of residents from rural to urban areas often for the economic opportunities offered by urban development, has further contributed to the increase in urban poverty in LMICs [3]. This rapid urbanization has been accompanied by significant shifts in health patterns, increasing the prevalence of non-communicable diseases (NCDs). Lung disease is known as a leading cause of mortality in LMICs, where it is reported to account for 15% of all deaths [7]

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