LincRNA-EPS and lincRNA-Cox2 regulate expression of KC, IL-6 and CCL5 in macrophages and mice treated with TLR2 and TLR4 agonists or during K. pneumoniae infection, but are dispensable for endotoxin tolerance

Abstract

Abstract Long non-coding RNAs (lncRNAs) are critical regulators of immune responses, but their role in sepsis is largely unknown. During sepsis, TLR sensing of microbes triggers the “cytokines storm”, disseminated intravascular coagulation and organ damage. Patients surviving systemic inflammatory response syndrome develop profound immunosuppression that resembles TLR tolerance and often succumb to secondary infections. To study the sepsis-associated “cytokine storm”, we used in vivo exposure of mice to LPS (endotoxemia) and Pam3Cys, while endotoxin tolerization of macrophages in vitro was employed to examine features of sepsis-associated immunosuppression. This study showed that LPS-treated macrophages decreased expression of lincRNA-EPS while upregulating lincRNA-Cox2 levels. Using knockout mice, we demonstrated that lincRNA-EPS acts to restrain KC, IL6 and CCL5 expression in the serum, spleen, lungs and liver of LPS or Pam3Cys-treated mice. Infection of lincRNA-EPS−/− macrophages with Klebsiella pneumoniae led to increased expression of IL-6 and CCL5 compared to wild-type cells. K. pneumoniae-infected wild-type and lincRNA-EPS−/− macrophages exhibited similar levels of TNF-α and bacterial 16S RNA. Compared to wild-type animals, pulmonary K. pneumoniae infection of lincRNA-EPS−/− mice resulted in higher levels of serum and lung IL-6 but decreased lung TNF-α. Finally, we showed that lincRNA-EPS and lincRNA-Cox2 are not required for LPS tolerance induction in macrophages. Thus, lincRNA-EPS and lincRNA-Cox2 shape macrophage-elicited cytokine induction upon exposure to microbial agonists and regulate host responses to K. pneumoniae.