BACKGROUND: MicroRNA-19a (miR-19a), an oncogenic microRNA, has been recently reported to target CD22 in B cell lymphoma cell lines, but its role in inflammatory response is unclear. CD22 is a negative regulator for BCR signaling, and we hypothesize that miR-19a regulates B cell response by targeting CD22 in sepsis.

MATERIAL AND METHODS: In order to determine whether miR-19a-CD22 pathway was involved in sepsis, and what role it played in the regulatory mechanisms, we detected the levels of miR-19a in B cells obtained from patients with sepsis, and measured the levels of miR-19a and CD22 expression in B cells activated by LPS in vitro. Additionally, we investigated the correlation between miR-19a and CD22, as well as the influence of this pathway on BCR signaling, in transfected B cells.

RESULTS: We found that septic patients displayed up-regulated miR-19a in B cells. In vitro, miR-19a was increased in activated B cells, with CD22 expression initially enhanced but subsequently decreased. Moreover, overexpression of miR-19a resulted in an amplified BCR signaling, while overexpression of CD22 attenuated the effect of miR-19a and increased its expression.

CONCLUSIONS: Our study demonstrated that miR-19a and CD22 comprised a feedback loop for B cell response in sepsis, providing a potential therapeutic target to recover the immune homeostasis.

Keywords: B-Lymphocytes - immunology, Analysis of Variance, Blotting, Western, DNA Primers - genetics, Feedback, Physiological, In Vitro Techniques, MicroRNAs - immunology, Real-Time Polymerase Chain Reaction, Sepsis - immunology, Sialic Acid Binding Ig-like Lectin 2 - immunology