Progressive Changes in the Plasma Metabolome during Malnutrition in Juvenile Pigs

Severe acute malnutrition (SAM) is one of the leading nutrition-related causes of death in children under five years of age. The clinical features of SAM are well documented, but a comprehensive understanding of the development from a normal physiological state to SAM is lacking. Characterizing the temporal metabolomic change may help to understand the disease progression and to define nutritional rehabilitation strategies. Using a piglet model we hypothesized that a progressing degree of malnutrition induces marked plasma metabolite changes. Four-week-old weaned pigs were fed a nutrient-deficient maize diet (MAL) or nutritionally optimized reference diet (REF) for 7 weeks. Plasma collected weekly was subjected to LC-MS for a nontargeted profiling of metabolites with abundance differentiation. The MAL pigs showed markedly reduced body-weight gain and lean-mass proportion relative to the REF pigs. Levels of eight essential and four nonessential amino acids showed a time-dependent deviation in the MAL pigs from that in the REF. Choline metabolites and gut microbiomic metabolites generally showed higher abundance in the MAL pigs. The results demonstrated that young malnourished pigs had a profoundly perturbed metabolism, and this provides basic knowledge about metabolic changes during malnourishment, which may be of help in designing targeted therapeutic foods for refeeding malnourished children

Comparison of temporal changes in electrolytes and hemoglobin (means ± SEM).

<p>Weekly measurements of electrolytes and hemoglobin levels in pig groups: MAIZE (n = 12), AGE-REF (n = 12). Differences in means *(p<0.05), ** (p<0.01), *** (p<0.001).</p

Comparison of temporal changes in plasma proANP, creatinine and urea (means ± SEM).

<p>Weekly measurements from pig groups: MAIZE (n = 12), AGE-REF (n = 12). Differences in means *(p<0.05), ** (p<0.01), *** (p<0.001).</p

Body and heart dimensions at the end of the experiment^*.

<p><b>*</b> Differences reported here for all pigs are also seen among the subsample of pigs used in echocardiography.</p><p>Data are (means ± sd).</p><p>^a,b,c Means not sharing a superscript are different (p<0.05).</p><p>Body and heart dimensions at the end of the experiment^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140472#t002fn001" target="_blank">*</a>}.</p

Myocardial Performance Index (MPI) derived by color tissue Doppler echocardiography.

<p><i>Top</i>: Apical left 4-chamber view in end-systole showing the position of M-mode line used for measurement of cardiac intervals. <i>Bottom</i>: Colour diagram of the tissue Doppler imaging M-mode of the anterior mitral leaflet. a = interval from mitral valve closing to opening; b = ejection time. Myocardial performance index = (a—b)/ b = 355 ms– 236 ms/236 ms = 0.50.</p

Intestinal proteins identified with differential expression between the AB and the untreated pigs (p<0.05).

a<p>Spot number consistent with those indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044929#pone-0044929-g003" target="_blank"><b>Figure 3</b></a>.</p>b<p>GI ID: Genbank identifier.</p>c<p>Protein score indicating the confidence of identification.</p>d<p>Expression quantity defined as the sum of optical density for each pixel of spot area (mean ± SEM, ×10⁴).</p

Macronutrient composition of experimental diets^*.

<p><b>*</b> Diet composition is listed in detail elsewhere [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140472#pone.0140472.ref027" target="_blank">27</a>].</p><p>Macronutrient composition of experimental diets^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140472#t001fn001" target="_blank">*</a>}.</p

Echocardiography results^*.

<p><b>*</b> Data are (means ± sd).</p><p>^a,b,c Means not sharing a superscript are different (p<0.05).</p><p>Echocardiography results^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140472#t003fn001" target="_blank">*</a>}.</p

Western-blot.

<p><b><i>Panel A</i></b>: Laminin receptor. <b><i>Panel B:</i></b> pyrophosphatase 1. <b><i>Panel C:</i></b> HSPB1. <b><i>Panel D:</i></b> haptoglobin. Expression levels are presented as mean±SEM. * p<0.05 in AB <i>vs</i> untreated pigs.</p

Intestinal proteins identified with differential expression between the AB and the untreated pigs (p<0.05).

a<p>Spot number consistent with those indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044929#pone-0044929-g003" target="_blank"><b>Figure 3</b></a>.</p>b<p>GI ID: Genbank identifier.</p>c<p>Protein score indicating the confidence of identification.</p>d<p>Expression quantity defined as the sum of optical density for each pixel of spot area (mean ± SEM, ×10⁴).</p