Tryptophan depletion in context of the inflammatory and general nutritional status of a low-income South African HIV-infected population

• Published in: Journal of health, population and nutrition Vol. 35; no. 1; p. 5
• Main Authors: Bipath, Priyesh, Levay, Peter F, Viljoen, Margaretha
• Format: Journal Article
• Language: English
• Published: Bangladesh BioMed Central 17.02.2016
• Subjects: Acquired immune deficiency syndrome; Adult; AIDS; Amino acids; Antiretroviral Therapy, Highly Active; Biomarkers - blood; Black People; C-reactive protein; CD4 antigen; CD4 Lymphocyte Count; Comparative studies; Cross-Sectional Studies; Deficiency Diseases - ethnology; Deficiency Diseases - etiology; Deficiency Diseases - psychology; Depletion; Developed countries; Diet; Diet - adverse effects; Diet - ethnology; Diet - psychology; Dietary intake; Female; Food security; Food Supply - economics; Hemoglobin; HIV; HIV Infections - blood; HIV Infections - drug therapy; HIV Infections - immunology; HIV Infections - physiopathology; Hospitals, Public; Human immunodeficiency virus; Humans; Immune response; Income; Indicators; Induction; Infections; Inflammation; Insecurity; Interleukin 6; Interleukins; Low income groups; Male; Middle Aged; Neopterin; Neopterin - blood; Nutritional Status; Outpatient Clinics, Hospital; Oxidation; Patients; Poverty Areas; Proteins; Public health; South Africa; Suburban Health Services; Tryptophan; Tryptophan - blood; Tryptophan - deficiency; Tryptophan 2,3-dioxygenase; South Africa
• ISSN: 2072-1315; 1606-0997; 2072-1315
• DOI: 10.1186/s41043-016-0042-4

The essential amino acid tryptophan cannot be synthesised in the body and must be acquired through dietary intake. Oxidation of tryptophan, due to immune induction of the enzyme indoleamine 2,3-dioxygenase (IDO), is considered to be the main cause of tryptophan depletion in HIV infection and AIDS. We examined plasma tryptophan levels in a low-income sub-Saharan HIV-infected population and compared it to that of developed countries. Tryptophan levels were further examined in context of the general nutritional and inflammatory status. This cross-sectional study included 105 HIV-positive patients recruited from the Kalafong Hospital in Pretoria, South Africa, and 60 HIV-negative controls. Patient tryptophan levels were in general markedly lower than those reported for developed countries. In contrast to reports from developed countries that showed tryptophan levels on average to be 18.8 % lower than their control values, tryptophan levels in our study were 44.1 % lower than our controls (24.4 ± 4.1 vs. 43.6 ± 11.9 μmol/l; p < 0.001). Tryptophan levels correlated with both CD4 counts (r = 0.341; p = 0.004) and with pro-inflammatory activity as indicated by neopterin levels (r = -0.399; p = 0.0001). Nutritional indicators such as albumin and haemoglobin correlated positively with tryptophan and negatively with the pro-inflammatory indicators neopterin, interleukin 6 and C-reactive protein. The most probable causes of the lower tryptophan levels seen in our population are food insecurity and higher levels of inflammatory activity. We contend that inflammation-induced tryptophan depletion forms part of a much wider effect of pro-inflammatory activity on the nutritional profile of HIV-infected patients.