METABOLOMIC PROFILING AND PROGNOSTICATION IN COVID-19-RELATED ARDS

SESSION TITLE: Late Breaking Posters in Critical Care SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/18/2022 01:30 pm - 02:30 pm PURPOSE: The majority of deaths in COVID-19 are due to acute respiratory distress syndrome (ARDS). We recently identified two subphenotypes among patients with COVID-19 related ARDS (C-ARDS) with divergent outcomes and responses to therapies. However, the precise biological processes that distinguish the subphenotypes, remain to be fully elucidated. High-resolution profiling of the metabolome can be used to gain precise insights into disease pathogenesis. The purpose of this study was to use precise, metabolomic profiling at the onset of C-ARDS to identify metabolic alterations and predict hospital mortality. METHODS: This was a retrospective, matched cohort study. Participants were adults with COVID-19 who met Berlin criteria for ARDS on the initial day of mechanical ventilation. All participants had prospectively banked plasma samples collected within one week of intubation. Twenty-five survivors to 90-days were matched on age, sex, and ethnicity to 25 patients who died within 28 days of intubation. Untargeted and targeted metabolomic analysis was performed using mass spectrometry and compared between survivors and non-survivors. Statistical analyses were performed with conditional logistic regression modeling with Bayesian inference. Compounds associated with mortality were identified using a cut-off of Bayes Factor (BF) > 3. Biological clustering analysis was performed using ChemRICH. Competitive modeling by four machine learning models—LASSO, adaptive LASSO, Random Forest, and XGBoost—was used to predict mortality. Three sets of predictors were explored: all metabolites, metabolites with BF > 1, and metabolites with BF > 3. RESULTS: Targeted and untargeted metabolomics of metabolic analytes yielded data for 30 bile acids, 340 biogenic amines, 522 complex lipids, 83 oxylipins, and 133 primary metabolites. Twenty-five compounds were identified with significant differences between survivors and non-survivors. Five compounds had increased levels associated with mortality, and 20 had decreased levels associated with mortality. Biological clustering analysis on these compounds identified four key clusters of compounds—unsaturated and saturated lysophosphatidylcholines, plasmalogens, and saturated ceramides—that were decreased amongst non-survivors. A machine learning-derived signature reflecting these metabolites showed excellent discrimination in predicting mortality, with the best model demonstrating area-under-the-receiver-operating-characteristic curve of 0.91. CONCLUSIONS: Metabolomic analysis identified differential enrichment of lipid metabolites in C-ARDS survivors compared to non-survivors. A machine learning model was able to accurately predict mortality from C-ARDS based on metabolomic profiles. CLINICAL IMPLICATIONS: Improved characterization of the metabolomic derangements in COVID-19 ARDS may lead to an enhanced understanding of drivers of mortality and improve prognostication and precision therapy. DISCLOSURES: No relevant relationships by Thomas Briese No relevant relationships by Xiaoyu Che No relevant relationships by Matthew Cummings No relevant relationships by Oliver Fiehn No relevant relationships by David Furfaro No relevant relationships by Wenhao Gou no disclosure on file for Walter Lipkin;no disclosure on file for Nischay Mishra;No relevant relationships by Max O'Donnell

Formation of eicosanoids and other oxylipins in human macrophages.

In this review it is attempted to summarize current studies about formation of eicosanoids and other oxylipins in different human macrophages. There are several reports on M1 and M2 cells, also other phenotypes have been described. The eicosanoids formed in the largest amounts are the COX products TxB₂ and PGE₂. Thus shortlived bioactive TxA₂ is a dominating product both in M1- and in M2-lineages, one exception seems to be M_{GM-CSF, TGFß} cells. 5-LOX products are produced in both M1 and M2 macrophages, as well as in not fully polarized cells of both lineages. M_M-CSF as well as M2 macrophages produced LTC₄ more readily compared to M1 lineage cells. In M_{GM-CSF, TGFß} cells LTB₄ is a major eicosanoid, in line with high expression of LTA₄ hydrolase. Recent reports described increased formation of leukotrienes in macrophages subjected to trained immunity with inflammatory transcriptional reprogramming. Also in macrophages derived from monocytes collected from post-COVID-19 patients. 15-LOX-1 is strongly upregulated in CD206⁺ M2 cells (M2a), differentiated in presence of IL-4. These macrophages also express 15-LOX-2. In incubations with pathogenic E. coli as well as other stimuli 15(S)-HETE and 17(S)-HDHA were major oxylipins formed. Also, the SPM precursor 5,15-diHETE and the SPM RvD5 were produced in considerable amounts, while other SPMs were less abundant. In M2 macrophages incubated with E. coli or S. aureus the cytosolic 15-LOX-1 enzyme accumulated to punctuate structures in a Ca²⁺ dependent manner with a relatively slow time course, leading to formation of mediators from endogenous substrate. Chalcones, flavone-like anti-inflammatory natural products, induced translocation of 15-LOX-1 in M2 cells, with high formation of 15-LOX derived oxylipins.

Plasma Oxylipins and Their Precursors Are Strongly Associated with COVID-19 Severity and with Immune Response Markers.

COVID-19 is characterised by a dysregulated immune response, that involves signalling lipids acting as mediators of the inflammatory process along the innate and adaptive phases. To promote understanding of the disease biochemistry and provide targets for intervention, we applied a range of LC-MS platforms to analyse over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). The second publication in a series reports the results of quantitative LC-MS/MS profiling of 63 small lipids including oxylipins, free fatty acids, and endocannabinoids. Compared to samples taken from ward patients, intensive care unit (ICU) patients had 2-4-fold lower levels of arachidonic acid (AA) and its cyclooxygenase-derived prostanoids, as well as lipoxygenase derivatives, exhibiting negative correlations with inflammation markers. The same derivatives showed 2-5-fold increases in recovering ward patients, in paired comparison to early hospitalisation. In contrast, ICU patients showed elevated levels of oxylipins derived from poly-unsaturated fatty acids (PUFA) by non-enzymatic peroxidation or activity of soluble epoxide hydrolase (sEH), and these oxylipins positively correlated with markers of macrophage activation. The deficiency in AA enzymatic products and the lack of elevated intermediates of pro-resolving mediating lipids may result from the preference of alternative metabolic conversions rather than diminished stores of PUFA precursors. Supporting this, ICU patients showed 2-to-11-fold higher levels of linoleic acid (LA) and the corresponding fatty acyl glycerols of AA and LA, all strongly correlated with multiple markers of excessive immune response. Our results suggest that the altered oxylipin metabolism disrupts the expected shift from innate immune response to resolution of inflammation.

Diet and Lifestyle Guidelines for Immunomodulation with Reference to Corona Virus Pandemic: A Scientific Statement of the International College of Nutrition

The immune system is comprised of lymph glands, lymph nodes, thymus gland, spleen, bone marrow, lymphocytes, and molecules such as antibodies and cytokines. It has a vast array of functionally different cells such as T and B lymphocytes, macrophages, neutrophils and mast cells. The ontogenesis of the immune system is comprised of the innate immune cells and the adaptive immune cells, where innate immune cells are the first defense mechanisms to respond to pathogenic environmental factors. There are multiple components of the adaptive immune cells, including immunoglobulins (Igs), T-cell receptors (TCR), and major histocompatibility complex (MHC) responsible for adaptive immunity. However, many elements of both the innate and adaptive immune systems are conserved in our bodies. The adaptive immunity is a type of immunity that develops when a person’s immune cells respond to a pathogen such as microorganism or vaccination. Environmental factors such as pathogenic bacteria or viruses, solar exposure, age, exercise, stress, diet, sleep quality and air pollutants can influence the immune system. There may be marked decline in the immune function due to attack of COVID-19. Most patients with mild COVID-19 develop an appropriate immune response that culminates with viral clearance. However, severe disease manifestations have been linked to lymphopenia and immune hyper-responsiveness leading to cytokine storm. It has been observed that in COVID-19, alveolar macrophages are epigenetically altered after inflammation, leading to long-term lung immune-paralysis. Western diets are known to have adverse effects on the immune function. However, Mediterranean-type diets rich in short-and long-chain polyunsaturated fatty acids (PUFA), vegetables, nuts and fruits, dairy products and fish and red wine, due to high content of vitamins, minerals and flavonoids may be useful in boosting immunity. Moderate physical activity may also cause an extensive increase in numerous and varied lipid super-pathway metabolites, including oxidized derivatives called oxylipins. Emerging evidence suggests that dietary supplements containing flavonoids, carotenoids, coenzyme Q10 (CoQ10), vitamins, minerals and antioxidants modulate gene and protein expression and thereby modify endogenous metabolic pathways, and consequently enhance the immunity. Mediterranean-type diet and multiple bioactive nutrients, fatty acids, amino acids, vitamins and minerals as well as moderate physical activity may be crucial for enhancing immunomodulation.