Distinct Plasma LPC Signatures Differentiate COVID-19 Sepsis from Other Sepsis Aetiologies

<b>Background/Objectives:</b> Low levels of lysophosphatidylcholine (LPC) in the blood can be used as a diagnostic marker for sepsis. SARS-CoV-2 infection, a more recent cause of sepsis, shares similarities with non-SARS-CoV-2 sepsis but also exhibits distinct features. We have recently shown that plasma cholesteryl ester levels are higher in patients with SARS-CoV-2 infection than in patients without, and this study analysed whether this may extend to differences in LPC, a bioactive constituent of lipoproteins. <b>Methods:</b> The plasma levels of 13 LPC species were measured by flow injection analysis tandem mass spectrometry (FIA-MS/MS) in 157 patients with systemic inflammatory response syndrome (SIRS), sepsis or septic shock. Of these patients, 24 had SARS-CoV-2 infection. <b>Results:</b> Patients with SIRS exhibited higher plasma levels of the minor LPC species LPC 15:0 and 22:4 compared to those with sepsis or septic shock. Five LPC species were also reduced in the plasma of 31 patients with liver cirrhosis; therefore, patients with cirrhosis or SIRS were excluded from subsequent analyses. Compared to 76 non-COVID-19 patients with sepsis or septic shock, SARS-CoV-2 infection in 21 patients was associated with significantly higher plasma levels of ten individual LPC species and total LPC concentration. In patients with sepsis/septic shock, LPC species showed negative correlations with procalcitonin and interleukin-6, and positive correlations with gamma-glutamyltransferase and cholesteryl ester levels. In contrast, no significant associations were observed between LPC levels and C-reactive protein, aminotransferases, or free cholesterol. <b>Conclusions:</b> Differential LPC levels, despite comparable disease severity, may serve as metabolic biomarkers to distinguish SARS-CoV-2 sepsis from other causes of sepsis and inform targeted therapeutic approaches.