The role of long noncoding RNAs (lncRNAs) in sepsis and systemic inflammation

• Applicant: Dr. Roland Elling
• Subject Area: Pediatric and Adolescent Medicine ; Immunology
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257463003

Sepsis remains to be a major threat to children both in developed and resource-poor countries. Despite recent advances, our pathophysiological picture of this complex syndrome is far from complete. The innate immune system is known to be the most important driver of the systemic inflammation during sepsis. Yet, the molecular networks balancing this potentially harmful inflammatory response are poorly defined. Recently, the group of Katherine Fitzgerald could identify long noncoding RNAs (lncRNAs) as novel regulatory elements for the innate inflammatory response. LncRNAs are non-protein coding molecules that have emerged as major regulators of gene expression. They are involved in a broad number of biological processes and human diseases. The group could demonstrate that pathogen recognition through germline-encoded receptors such as Toll-like-receptors (TLRs) induces numerous lncRNAs. Among these, lncRNA-Cox2 was identified as a key regulator of the innate inflammatory response in vitro, regulating a wide range of immune genes including cytokines like interleukin-6, chemokines like RANTES and various interferon-stimulated genes. Of note, lncRNA-Cox2 mediates both gene activation and repression and thereby controls the inflammatory response in a very versatile manner. However, the biological role of the molecule in vivo remains to be elucidated.In this grant proposal, I aim to test the hypothesis that lncRNA-Cox2 regulates the innate immune response during systemic inflammation and sepsis. In the first step, I will perform a whole-transcriptome analysis (RNA-Seq) in mouse wildtype macrophages and macrophages where lncRNA-Cox2 has been silenced by RNA interference after stimulation with S.pneumoniae in vitro. This will allow to characterize the profile of macrophage lncRNAs induced by pneumococci and will allow to define target genes of lncRNA-Cox2 during pneumococcal infection. Moreover, I will characterize the macrophage phenotype after knockdown of lncRNA-Cox2 to understand whether lncRNA-Cox2 regulates the effector functions of these myeloid cells. Following that, I will characterize the phenotype and function of lncRNA-Cox2 during sterile inflammation (endotoxin shock model) and in a model of pneumococcal pneumonia-induced sepsis in vivo. I will analyze the temporal as well as spatial expression pattern of lncRNA-Cox2 and other pneumococci-induced lncRNAs in the innate immune compartment in both models. Moreover, I will generate a bone marrow chimeric mouse model with tetracycline-inducible lncRNA-Cox2 knockdown. With the help of this model, I will characterize the biological role of the regulatory RNA during pneumococcal sepsis and endotoxin shock in vivo. Taken together, these experiments will help to understand the contribution of lncRNAs to the pathogenesis of sepsis. This could ultimately lead to the development of novel diagnostic tools and therapeutic concepts in sepsis.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professorin Dr. Katherine A. Fitzgerald, Ph.D.