3.3 Critical lipids screening through Venn Diagram and Pathway
analysis
We identified 44 lipids differentially expressed both in the mild and
severe ICP group compared with the control group (Fig 3A). Detailed
information regarding the 44 differential lipids was shown in Table 2.
To screen critical lipids that are associated with ICP, we combined the
previously published ICP plasma lipidomics data for further
analysis23. In the previously reported data, Sun et al
revealed differentially expressed plasma lipids in ICP patients, and we
identified three differential lipids co-expressed both in ICP placenta
and ICP plasma (Fig 3A). These three lipids are
SM
(d42:1), SM (d18:1/24:1) and PC (17:0/18:2), and their expression level
in the ICP placenta is significantly altered (Fig 3C). Based on the
identified 44 differential lipids, we conducted a pathway analysis to
reveal possible metabolic pathways involved in ICP onset. The results of
the pathway analysis show that the significantly altered lipids were
enriched in autophagy regulation, glycerophospholipid metabolism and
GPI-anchor biosynthesis (Fig 3B). It was reported autophagy is closely
related to ICP pathogenesis14, 25, 26, we further
analyzed the individual autophagy pathways and found 5 PE lipids are
closely in correlation with autophagy (Fig S1), including PE
(16:0/18:1), PE (16:0/20:2), PE (18:1/20:3), PE (18:1/20:4), exhibited
increased level in ICP placenta, while PE (18:0/22:4) exhibited
decreased expression level (Fig 3C), indicate these lipids may play a
pivotal role in the occurrence and development of ICP.