Hemodialysis and Plasma Oxylipin Biotransformation in Peripheral Tissue

Effect of cardiopulmonary bypass on plasma and erythrocytes oxylipins

BACKGROUND

Oxylipins, the oxidative metabolites of polyunsaturated fatty acids (PUFAs), serve as key mediators of oxidative stress, inflammatory responses, and vasoactive reactions in vivo. Our previous work has established that hemodialysis affects both long chain fatty acids (LCFAs) and oxylipins in plasma and erythrocytes to varying degrees, which may be responsible for excess cardiovascular complications in end-stage renal disease. In this study, we aimed to determine changes in blood oxylipins during cardiopulmonary bypass (CPB) in patients undergoing cardiac surgery to identify novel biomarkers and potential metabolites of CPB-related complications. We tested the hypothesis that CPB would differentially affect plasma oxylipins and erythrocytes oxylipins.

METHODS

We conducted a prospective observational study of 12 patients undergoing elective cardiac surgery with expected CPB procedure. We collected venous and arterial blood samples before CPB, 15 and 45 min after the start of CPB, and 60 min after the end of CPB, respectively. Oxylipins profiling in plasma and erythrocytes was achieved using targeted HPLC-MS mass spectrometry.

RESULTS

Our results revealed that most venous plasma diols and hydroxy- oxylipins decreased after CPB initiation, with a continuous decline until the termination of CPB. Nevertheless, no statistically significant alterations were detected in erythrocytes oxylipins at all time points.

CONCLUSIONS

CPB decreases numerous diols and hydroxy oxylipins in blood plasma, whereas no changes in erythrocytes oxylipins are observed during this procedure in patients undergoing cardiac surgery. As lipid mediators primarily responsive to CPB, plasma diols and hydroxy oxylipins may serve as potential key biomarkers for CPB-related complications.

Oxylipins as Biomarkers for Aromatase Inhibitor-Induced Arthralgia (AIA) in Breast Cancer Patients

Aromatase inhibitor-induced arthralgia (AIA) presents a major problem for patients with breast cancer but is poorly understood. This prospective study explored the inflammatory metabolomic changes in the development of AIA. This single-arm, prospective clinical trial enrolled 28 postmenopausal women with early-stage (0-3) ER+ breast cancer starting adjuvant anastrozole. Patients completed the Breast Cancer Prevention Trial (BCPT) Symptom Checklist and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) at 0, 3, and 6 months. The plasma levels of four polyunsaturated fatty acids (PUFAs) and 48 oxylipins were quantified at each timepoint. The subscores for WOMAC-pain and stiffness as well as BCPT-total, hot flash, and musculoskeletal pain significantly increased from baseline to 6 months (all p < 0.05). PUFA and oxylipin levels were stable over time. The baseline levels of 8-HETE were positively associated with worsening BCPT-total, BCPT-hot flash, BCPT-musculoskeletal pain, WOMAC-pain, and WOMAC- stiffness at 6 months (all p < 0.05). Both 9-HOTrE and 13(S)-HOTrE were related to worsening hot flash, and 5-HETE was related to worsening stiffness (all p < 0.05). This is the first study to prospectively characterize oxylipin and PUFA levels in patients with breast cancer starting adjuvant anastrozole. The oxylipin 8-HETE should be investigated further as a potential biomarker for AIA.

Detoxification Cytochrome P450s (CYPs) in Families 1-3 Produce Functional Oxylipins from Polyunsaturated Fatty Acids

This manuscript reviews the CYP-mediated production of oxylipins and the current known function of these diverse set of oxylipins with emphasis on the detoxification CYPs in families 1-3. Our knowledge of oxylipin function has greatly increased over the past 3-7 years with new theories on stability and function. This includes a significant amount of new information on oxylipins produced from linoleic acid (LA) and the omega-3 PUFA-derived oxylipins such as α-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). However, there is still a lack of knowledge regarding the primary CYP responsible for producing specific oxylipins, and a lack of mechanistic insight for some clinical associations between outcomes and oxylipin levels. In addition, the role of CYPs in the production of oxylipins as signaling molecules for obesity, energy utilization, and development have increased greatly with potential interactions between diet, endocrinology, and pharmacology/toxicology due to nuclear receptor mediated CYP induction, CYP inhibition, and receptor interactions/crosstalk. The potential for diet-diet and diet-drug/chemical interactions is high given that these promiscuous CYPs metabolize a plethora of different endogenous and exogenous chemicals.