Is Lipopolysaccharide-Induced Lipid Metabolism Disorder in Testis of Rats a Consequence of Plasma Lipid Changes?

Abstract

Purpose

The systemic infection and inflammation can result in testes injury, whereas the exact mechanism is unknown. The lipid metabolism has a dual impact on controlling metabolism and inflammation, which is a potential pathway. The objective of this study was to determine if changes in plasma lipids during lipopolysaccharide (LPS)-induced systemic inflammation affect the dysregulation of testes lipid metabolism.

Materials and Methods

LPS (5 mg/kg) was used to induce systemic inflammation in rats after a single intraperitoneal injection. After 4 weeks, the rats were sacrificed, and the serum and testes were used for laboratory measurements and histology examination. Plasma and testis were used for lipidomics analysis based the liquid chromatography-mass spectrometry. Spearman rank correlation analysis was used to compare the correlation of differential lipids in phospholipids, glycerolipids, and sphingolipids between testis and plasma.

Results

LPS raised the levels of cytokines in serum and testis, decreased the activities of antioxidant enzymes, increased the levels of lipid peroxidation products, and damaged testis tissue. In testis and plasma, 146 and 401 differential lipids, mostly phosphatidylcholine, phosphatidylethanolamine an so on, were found in comparison to the control group. Correlation analysis produced a total of 2528 correlation coefficients, 1150 of which were P<0.05 and accounted for 45.49%.

Conclusion

The changes of lipid composition and content in the testis are related to cytokine overload and oxidative stress. Testis lipid metabolism disorders caused by LPS-induced systemic inflammation are lack of a correlation with plasma lipid changes, and are likely owing to interference with the testis itself.

Keywords:

• systemic inflammation
• infertility
• lipidomics
• oxidative stress
• correlation analysis

Abbreviations

ROS, reactive oxygen species; TLRs, Toll-like receptors; LPS, Lipopolysaccharide; PI (4,5) P2, phosphatidylinositol 4,5-bisphosphate; LC-MS, Liquid chromatography-mass spectrometry; PCA, Principal component analysis; OPLS-DA, Orthogonal projections to Latent Structures-discriminant analysis; VIP, variable influence on projection; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PI, phosphatidylinositol; SM, sphingomyelin; DG, diglyceride; TG, triglyceride; Cer, Ceramides; Hex2cer, dihexosylceramides; LPC, lysophosphatidylcholine; LPE, lysophosphatidylethanolamine; LPG, lysophosphatidylglycerol; MG, monoglyceride; PG, phosphatidylglycerol; PS, phosphatidylserine.

Data Sharing Statement

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Ethics Approval for Animal Study

The experiment was authorized by the Experimental Animal Ethics Committee of East Region Military Command General Hospital (Jinling Hospital) and carried out according to the National Institutes of Health protocol to laboratory animal care and use.

Author Contributions

All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; agreed to submit to the current journal; gave final approval of the version to be published; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (NO. 81771646).