Effects of short- and long-term glucocorticoid-induced osteoporosis on plasma metabolome and lipidome of ovariectomized sheep

Abstract

Background: Understanding the metabolic and lipidomic changes that accompany bone loss in osteoporosis might provide insights about the mechanisms behind molecular changes and facilitate developing new drugs or nutritional strategies for osteoporosis prevention. This study aimed to examine the effects of short- or long-term glucocorticoid-induced osteoporosis on plasma metabolites and lipids of ovariectomized (OVX) sheep.

Methods: Twenty-eight aged ewes were divided randomly into four groups: an OVX group, OVX in combination with glucocorticoids for two months (OVXG2), and OVX in combination with five doses of glucocorticoids (OVXG5) to induce bone loss, and a control group. Liquid chromatography-mass spectrometry untargeted metabolomic analysis was applied to monthly plasma samples to follow the progression of osteoporosis over five months.

Results: The metabolite profiles revealed significant differences in the plasma metabolome of OVX sheep and OVXG when compared with the control group by univariate analysis. Nine metabolites were altered, namely 5-methoxytryptophan, valine, methionine, tryptophan, glutaric acid, 2-pyrrolidone-5-carboxylic acid, indole-3-carboxaldehyde, 5-hydroxylysine and malic acid. Similarly, fifteen lipids were perturbed from multiple lipid classes such as lysophoslipids, phospholipids and ceramides.

Conclusion: This study showed that OVX and glucocorticoid interventions altered the metabolite and lipid profiles of sheep, suggesting that amino acid and lipid metabolisms are potentially the main perturbed metabolic pathways regulating bone loss in OVX sheep.

Keywords: Lipidome; Metabolome; OVX sheep; Osteoporosis.

Fig. 1

Overview of the study design and specific statistical analyses. Short-term study: Plasma metabolite and lipid profiles of 28 sheep, control group n = 10, OVX group n = 12, OVXG n = 6, were analyzed by multivariate and univariate analyses from baseline to two months. Long-term study: Plasma metabolite and lipid profiles of 17 sheep, control group n = 5, OVX group n = 6, OVXG2 n = 3, OVXG5 n = 3, were analyzed by multivariate and univariate analyses from baseline (month zero) to five months

Fig. 2

Heatmap showing the longitudinal response for each metabolite in the short-term approach. Data were calculated using a linear mixed model and mean of the relative intensities of the different treatment groups (control group (n = 10), OVX group (n = 12) and OVXG (n = 6)). Blue and yellow indicate decreased and increased relative intensities, respectively

Fig. 3

Heatmap showing the longitudinal response for each metabolite in the long-term approach. Data were calculated using a linear mixed model and mean of the relative intensities of the different treatment groups (control group (n = 5), OVX group (n = 6), OVXG2 (n = 3) and OVXG5 (n = 3)). Blue and yellow indicate decreased and increased relative intensities, respectively

Fig. 4

Heatmap showing the longitudinal response for each lipid in the short-term approach. Data were calculated using a linear mixed model and mean of the relative intensities of the different treatment groups (control group (n = 10), OVX group (n = 12) and OVXG (n = 6)). PG = phosphatidylglycerol, CL = cardiolipin, PI = phosphatidylinositol. Blue and yellow indicate decreased and increased relative intensities, respectively

Fig. 5

Heatmap showing the longitudinal response for each lipid in the long-term approach. Data were calculated using a linear mixed model and mean of the relative intensities of the different treatment groups (control group (n = 5), OVX group (n = 6), OVXG2 (n = 3) and OVXG5 (n = 3). CL = cardiolipin, CerP = ceramide 1-phosphates, PI = phosphatidylinositol, PA = phosphatidic acid, lysoPE = lysophosphatidylethanolamines, PS = phosphatidylserines, PG = phosphatidylglycerol. Blue and yellow indicate decreased and increased relative intensities, respectively