Serum Levels of Interleukins 6 and 8 in Malnourished Children With Acute Diarrhea

Acute gastroenteritis remains a common health problem among children worldwide with significant morbidity, mortality, and economic burden. Diarrheal diseases account for more than half-million deaths of children under 5 years old every year, most of which take place in low- and middle-income countries (LMICs). Moreover, diarrheal diseases are a leading cause of emergency visits and hospitalization. According to the WHO, acute diarrhea is classified into acute watery diarrhea, acute bloody diarrhea (dysentery), persistent diarrhea, and diarrhea with severe malnutrition. Acute watery diarrhea is the most common category in both high and LMICs. Viral infections (e.g., rotavirus, norovirus, adenovirus) are the leading causes of acute watery diarrhea in children (up to 90% of cases), while bacteria (e.g., shigella, salmonella, Campylobacter, enterotoxigenic E. coli) and parasites (e.g., Cryptosporidium, Giardia, and E. histolytica) account for the remainder of cases.

Cytokines can be used as markers of acute infections, including acute gastroenteritis. Interleukin-6 (IL-6) is produced by lymphoid and non-lymphoid cells and plays important role in regulation of immunity, acute-phase response, and hematopoiesis; IL-6 has a well-known role in the defense mechanism in acute gastroenteritis. Interleukin-8 (IL-8) functions in chemotaxis of inflammatory cells, such as neutrophils and lymphocytes, to the site of inflammation, Both IL-6 and IL-8 are critical for immunity against mucosal infections; they are released from the epithelial cells of the gastrointestinal tract to mount its inflammatory responses to infectious agents at local and systemic levels.

Some studies investigated the role of IL-6 and IL-8 as biomarkers for acute diarrhea in children. Results showed significantly increased serum levels of IL-6 and IL-8 in children with acute GE compared with healthy controls. Moreover, IL-6 is significantly elevated in bacterial gastroenteritis in comparison to viral gastroenteritis. However, none of these studies included children with severe acute malnutrition.

Severe acute malnutrition (SAM) is a severe form of malnutrition resulting from inadequate or poor quality dietary intake. This is a serious public health problem, particularly in developing countries. SAM can be classified into marasmus, characterized by overt loss of subcutaneous fat and muscle mass, and Kwashiorkor, characterized by bilateral pitting edema of lower limbs.

Malnutrition is one of the most common causes of impaired immune function in children. Malnutrition leads to defects of phagocytosis, chemotactic function of neutrophils and monocytes, complement system and opsonization, and the function of antigen presenting cells.