Molecular mechanisms underlying application of serum procalcitonin and stool miR-637 in prognosis of acute ischemic stroke.

We and others have reported that the serum procalcitonin (PCT) level has a demonstrative role in predicting the long-term mortality after acute ischemic stroke (AIS) in Chinese population. Nevertheless, the underlying mechanisms remain ill-defined. In the current study, we further detected a close association of stool microRNA-637 (miR-637) levels with the long-term mortality after AIS in Chinese population. Moreover, the serum PCT and stool miR-637 levels appeared to be inversely correlated. AIS patients with lower levels of stool miR-637 appeared to predict more severe mortality in the long-term. Since PCT has been shown to be mainly produced by the neuroendocrine cells in the intestine, we used an intestine neuroendocrine cell line to study the relationship between miR-637 and PCT. Bioinformatics analyses showed that miR-637 targeted the 3'-UTR of PCT mRNA to inhibit its translation, and thus the levels of PCT protein production and secretion, which was proved by luciferase reporter assay. Together, our data reveal that the molecular mechanisms underlying application of serum PCT and stool miR-637 in prognosis of AIS, in which miR-637 in intestine neuroendocrine cells may be reduced during AIS to allow more PCT to be released into serum to be detected.