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The protein metabolic response to HIV infection in young children
Farook Jahoor1, Stuart Abramson, William C Heird
1US Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA. fjahoor@bcm.tmc.edu
Insights
HIV infection in children impairs protein balance due to increased protein breakdown. The acute phase protein response shows elevated positive acute phase proteins (APPs) and normal negative APPs, indicating altered protein metabolism.
Area of Science:
- Pediatric Infectious Diseases
- Human Immunodeficiency Virus (HIV) Research
- Nutritional Biochemistry
Background:
- Growth failure in HIV-infected children may stem from poor protein deposition.
- The specific protein metabolic response to HIV in young children remains unclear.
Purpose of the Study:
- To compare whole-body and splanchnic protein kinetics in HIV-infected versus uninfected children.
- To assess the synthesis of acute phase proteins (APPs) in these groups.
Main Methods:
- Measured whole-body and splanchnic leucine kinetics in fed HIV-infected and control children.
- Quantified synthesis rates of positive and negative APPs.
Main Results:
- HIV-infected children had lower energy/protein intake and leucine balance.
- HIV-infected children exhibited faster leucine flux and splanchnic extraction.
- Elevated positive APPs and fibrinogen synthesis were observed in HIV-infected children, with lower negative APPs (albumin, HDL apoA-I) not linked to synthesis rates.
Conclusions:
- HIV infection in children, even without secondary infections, leads to negative protein balance by hindering protein catabolism downregulation.
- The acute phase protein response in HIV infection involves increased positive APPs and normal levels of some negative APPs.
Background:
Growth failure often precedes secondary infections in HIV-infected infants and children, suggesting that inadequate protein deposition may be an early manifestation of infection by the virus. However, the protein metabolic response elicited by the virus in young children is unknown.
Objective:
We compared children with HIV infection and age-matched children without HIV infection with regard to whole-body and splanchnic protein kinetics and synthesis of acute phase proteins (APPs).
Design:
Whole-body and splanchnic leucine kinetics and fractional and absolute synthesis rates of 2 positive and 4 negative APPs were measured in 6 asymptomatic, HIV-infected children (4 males and 2 females) aged 6-17 mo and 4 uninfected children (3 females and 1 male) aged 7-9 mo who were in the fed state.
Results:
Compared with the control children, the HIV-infected children had significantly lower dietary energy and protein intakes and leucine balance and significantly faster leucine flux and fractional splanchnic leucine extraction; there was no significant difference between the groups in leucine oxidation rates. The HIV-infected children also had significantly higher plasma concentrations and absolute synthesis rates of the positive APPs and a significantly higher fractional synthesis rate of fibrinogen. The concentrations of 2 of the 4 negative APPs, albumin and HDL apolipoprotein A-I, were significantly lower in the HIV-infected children but were not associated with slower synthesis rates.
Conclusions:
Children with HIV infection but without secondary infection have reduced protein balance because of an inability to down-regulate protein catabolism. Furthermore, the acute phase protein response elicited by HIV infection is characterized by higher concentrations and synthesis rates of positive APPs without lower concentrations of some negative APPs.