Yie Hou Lee1, Joan Xiaohui Yang2, John Carson Allen3, Chuen Seng Tan4, Bernard Su Min Chern5, Tse Yeun Tan6, Heng Hao Tan7, Citra Nurafah Zaini Mattar8, Jerry Kok Yen Chan7. 1. KK Research Centre, KK Women's and Children's Hospital, Singapore; OBGYN-Academic Clinical Program, Duke-NUS Medical School, Singapore. Electronic address: gmsleeyh@nus.edu.sg. 2. Division of Obstetrics and Gynecology, KK Women's and Children's Hospital, Singapore. 3. Centre for Quantitative Medicine, Duke-NUS Medical School, Singapore. 4. Saw Swee Hock School of Public Health, National University of Singapore, Singapore. 5. OBGYN-Academic Clinical Program, Duke-NUS Medical School, Singapore; Division of Obstetrics and Gynecology, KK Women's and Children's Hospital, Singapore. 6. Department of Reproductive Medicine, KK Women's and Children's Hospital, Singapore. 7. OBGYN-Academic Clinical Program, Duke-NUS Medical School, Singapore; Department of Reproductive Medicine, KK Women's and Children's Hospital, Singapore. 8. Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Abstract
OBJECTIVE: To characterize the peritoneal fluid (PF) sphingolipid profile in endometriosis-associated infertility (EAI), and to assess the plausible functional role(s) of ceramides in oocyte maturation potential. DESIGN: Retrospective case-control study and in vitro mouse oocyte study. SETTING: University-affiliated hospital and university laboratory. SUBJECTS: Twenty-seven infertile patients diagnosed with endometriosis and 20 infertile patients who did not have endometriosis; BALB/c female mice. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): PF sphingolipid concentrations. Number of metaphase II (MII) mouse oocytes. RESULT(S): Liquid chromatography-tandem mass spectrometry revealed 11 significantly elevated PF sphingolipids in infertile women with severe endometriosis compared with infertile women without endometriosis (change >50%, false discovery rate ≤10%). Logistic regression analysis identified three very-long-chain ceramides potentially associated with EAI. Functional studies revealed that very-long-chain ceramides may compromise or induce murine MII oocyte maturation. The oocyte maturation effects induced by the very long-chain ceramides were triggered by alterations in mitochondrial superoxide production in a concentration-dependent manner. Scavenging of mitochondrial superoxide reversed the maturation effects of C24:0 ceramide. CONCLUSION(S): EAI is associated with accumulation of PF very-long-chain ceramides. Mouse studies demonstrated how ceramides affect MII oocyte maturation, mediating through mitochondrial superoxide. These results provide an opportunity for direct functional readout of pathophysiology in EAI, and future therapies targeted at this sphingolipid metabolism may be harnessed for improved oocyte maturation.
OBJECTIVE: To characterize the peritoneal fluid (PF) sphingolipid profile in endometriosis-associated infertility (EAI), and to assess the plausible functional role(s) of ceramides in oocyte maturation potential. DESIGN: Retrospective case-control study and in vitro mouse oocyte study. SETTING: University-affiliated hospital and university laboratory. SUBJECTS: Twenty-seven infertilepatients diagnosed with endometriosis and 20 infertilepatients who did not have endometriosis; BALB/c female mice. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): PF sphingolipid concentrations. Number of metaphase II (MII) mouse oocytes. RESULT(S): Liquid chromatography-tandem mass spectrometry revealed 11 significantly elevated PF sphingolipids in infertilewomen with severe endometriosis compared with infertilewomen without endometriosis (change >50%, false discovery rate ≤10%). Logistic regression analysis identified three very-long-chain ceramides potentially associated with EAI. Functional studies revealed that very-long-chain ceramides may compromise or induce murine MII oocyte maturation. The oocyte maturation effects induced by the very long-chain ceramides were triggered by alterations in mitochondrial superoxide production in a concentration-dependent manner. Scavenging of mitochondrial superoxide reversed the maturation effects of C24:0 ceramide. CONCLUSION(S): EAI is associated with accumulation of PF very-long-chain ceramides. Mouse studies demonstrated how ceramides affect MII oocyte maturation, mediating through mitochondrial superoxide. These results provide an opportunity for direct functional readout of pathophysiology in EAI, and future therapies targeted at this sphingolipid metabolism may be harnessed for improved oocyte maturation.