Objective: Pregnancy reduces the annualized relapse rate (ARR) in multiple sclerosis (MS). However it is temporarily increased at puerperium. The exact mechanism underlying this clinical observation remains unknown.
We aimed to explore the changes of the short-chain fatty acids (SCFAs) profiles in MS patients and healthy women (HCW) during pregnancy, and to assess any potential biomarker predicting the appearance of relapses during pregnancy and postpartum.
Methods: We included 53 pregnant MS patients and 21 HCW followed at Hospital Universitario Gregorio Marañón between 2007 and 2018. Patients were evaluated at every trimester of pregnancy and in the puerperium. Serum SCFAs were measured by liquid chromatography-mass spectrometry
Results: Seventeen patients (32%) experienced relapses during pregnancy or puerperium (ACT group) and 37(68%) did not (NO-ACT group). We did not found differences in clinical characteristics or treatment status between the two groups. We observed differences in the SCFAs profile between ACT:NO-ACT groups during pregnancy and puerperium. Acetate levels were higher during the pregnancy-puerperium period in MS patients, regardless of clinical activity, compared to HCW (p: 0.0001). Interestingly, levels of propionate and butyrate below 1,985 μM (1,283 - 3.55) and 0.515 μM (0.01-2.943) respectively during the first trimester were associated with relapses during the pregnancy-puerperium period (p: 0.0001). The ACT group had a lower ratio of propionate/acetate and butyrate/acetate during pregnancy compared to NO-ACT group (<0.0001). The ROC curve showed that a propionate/acetate ratio of 0.36 (AUC 0.96, sensitivity 94%, specificity 92%;) has an OR=165 [CI: 10.2-239.4], p <0.0001) to predict relapses during pregnancy-puerperium.
Conclusions: SCFA levels during pregnancy may be associated with clinical activity in MS, and that their measurement could be useful in predicting the occurrence of relapses during this pregnancy-puerperium period