Phenotypic upregulation of hexocylceramides and ether-linked phosphocholines as markers of human extreme longevity

Abstract

Centenarians and their relatives possess a notable survival advantage, with higher longevity and reduced susceptibility to major age-related diseases. To date, characteristic omics profiles of centenarians have been described, demonstrating that these individuals with exceptional longevity regulate their metabolism to adapt and incorporate more resilient biomolecules into their cells. Among these adaptations, the lipidomic profile stands out. However, it has not yet been determined whether this lipidomic profile is specific to centenarians or is the consequence of extreme longevity genetics and is also present in centenarians' offspring. This distinction is crucial for defining potential therapeutic targets that could help delay the aging process and associated pathologies. We applied mass-spectrometry-based techniques to quantify 569 lipid species in plasma samples from 39 centenarians, 63 centenarians' offspring, and 69 noncentenarians' offspring without familial connections. Based on this profile, we calculated different indexes to characterize the functional and structural properties of plasma lipidome. Our findings demonstrate that extreme longevity genetics (centenarians and centenarians' offspring) determines a specific lipidomic signature characterized by (i) an enrichment of hexosylceramides, (ii) a decrease of specific species of ceramides and sulfatides, (iii) a global increase of ether-PC and ether-LPC, and (iv) changes in the fluidity and diversity of specific lipid classes. We point out the conversion of ceramides to hexosylceramides and the maintenance of the levels of the ether-linked PC as a phenotypic trait to guarantee extreme longevity. We propose that this molecular signature is the result of an intrinsic adaptive program that preserves protective mechanisms and cellular identity.

Keywords: centenarians; cententarians' offspring; ether lipids; extreme longevity; hexocylceramides; lipidomics.

FIGURE 1

(a) Lipidomic workflow used for the study. (b) Principal Component Analysis using all the lipid species detected. (c) Biological interpretation: Biomarkers of centenarians: Those lipids that are significantly different between centenarian and noncentenarian (centenarians' offsprings and noncentenarians' offspring) individuals. Biomarkers of extreme longevity: Those lipids that are common in individuals with longevous genetic background (centenarians and centenarians offsprings) during life. Adaptive biomarkers of extreme longevity: (i) those biomarkers that are statistically different between control and centenarians' offsprings; and (ii) those biomarkers that are different between three groups, and the concentrations of these species in centenarians' offsprings are intermediate between control and centenarians. CO, Centenarians' offspring, Cent, Centenarians; NCO, Noncentenarians' offspring.

FIGURE 2

Heatmap representation of the lipid species that defines the lipidomic fingerprint of extreme longevity (a) and the functional and structural properties of the lipidome (b). FlI is calculated according to chain length and double bonds of their fatty acids. DvI represents the probability that two lipids randomly selected from a sample will belong to different species. Higher diversity values indicate higher diversity of lipids within the specified lipid class. AC, Aclycarnitines; ACL, Average Chain Length; CE, Cholesterol esters; Cent, Centenarians; Cer, Ceramides; CO, Centenarians' offspring; DBI, Double Bond Index; dhCer, Dihydroceramide; DvI, Diversity Index; FA, Fatty acids; FlI, Fluidity Index; Hex2Cer, Hexosyl2ceramides; Hex3Cer, Hexosyl3ceramides; HexCer, Hexosylceramides; LPC(O), Lysophosphatidylcholine(O); LPC(P), Lysophosphatidylcholine(P); LPC, Lysophosphatidylcholine; NCO, Noncentenarians' offspring; PC(O), Phosphatidylcholine(O); PC(P), Phosphatidylcholine(P); PC, Phosphatidylcholine; SAT, Saturation; TG, Triglycerides; Total_AC, Sum of the concentration of all AC species; Total_Hex2Cer, Sum of the concentration of all Hex2Cer species; Total_HexCer, Sum of the concentration of all HexCer species; Total_LPC(O), Sum of the concentration of all LPC(O) species.

FIGURE 3

Lipid species significantly associated with extreme longevity genotype (centenarians and centenarians offsprings) grouped by class. Line chart representing all the lipid species of each class. Total concentration of each class is represented by dot‐dashed lines. Only statistically different species are colored. The percentage of lipid species affected by extreme longevity with respect to total species detected as indicated for each class. Overrepresentation of lipids in each class is calculated using a hypergeometric test and overrepresented classes are framed in gray (Hex2Cer, LPC, and LPC(O)). AC, Aclycarnitines; CE, Cholesterol esters; Cent, Centenarians; Cer, Ceramides; CO, Centenarians' offspring; FA, Fatty acids; Hex2Cer, Hexosyl2ceramides; Hex3Cer, Hexosyl3ceramides; HexCer, Hexosylceramides; LPC(O), Lysophosphatidylcholine(O); LPC(P), Lysophosphatidylcholine(P); LPC, Lysophosphatidylcholine; NCO, Noncentenarians' offspring; PC(O), Phosphatidylcholine(O); PC(P), Phosphatidylcholine(P); PC, Phosphatidylcholine; TG, Triglycerides.

FIGURE 4

Functional properties of lipid species grouped by lipid class. Only the lipid classes that present statistically significant differences in Diversity Index (DvI) and/or Fluidity Index (FlI) between groups are selected. Biomarkers of centenarians are colored in red; biomarkers of extreme longevity in yellow and adaptive biomarkers of extreme longevity in gray. AC, Acylcarnitine; Cer, Ceramide; DG, Diglyceride; dhCer, Dihydroceramide; HexCer, HexosylCeramides; LPC, Lysophosphocholines; LPI, Lysophosphatidylinositol; PC(O), Phosphocholine(O); PC(P), Phosphocholine(P); PE(O), Phosphoethanolamine(O); PE, Phosphoethanolamine; PG, Phosphoglycerol; SM, Sphingomyeline; TG, Trygliceride. DvI represents the probability that two lipids randomly selected from a sample will belong to different species. Higher diversity values indicate higher diversity of lipids within the specified lipid class.

FIGURE 5

Hexosylceramide formation is favored in extreme longevity. FlI is calculated according to chain length and double bonds of their fatty acids. DvI represents the probability that two lipids randomly selected from a sample will belong to different species. Higher diversity values indicate higher diversity of lipids within the specified lipid class. Cent, Centenarians; Cer, Ceramide; CO, Centenarians' offspring; dhCer, Dihydroceramide; DvI, Diversity Index; FlI, Fluidity Index; Hex2Cer, Hexosyl2ceramides; Hex3Cer, Hexosyl3ceramides; HexCer, Hexosylceramides; NCO, Noncentenarians' offspring.

FIGURE 6

Ether‐linked phosphatidylcholines are increased in extreme longevity. FlI is calculated according to chain length and double bonds of their fatty acids. DvI represents the probability that two lipids randomly selected from a sample will belong to different species. Higher diversity values indicate higher diversity of lipids within the specified lipid class. Cent, Centenarians; CO, Centenarians' offspring; DG, Diglyceride; DvI, Diversity Index; FlI, Fluidity Index; LPC(O), Lysophosphatidylcholine(O); LPC, Lysophosphatidylcholine; NCO, Noncentenarians' offspring; PC(O), Phosphatidylcholine(O); PC(P), Phosphatidylcholine(P); PC, Phosphatidylcholine; PE, Phosphatidylethanolamine.