Cardiac Fibroblast Functionality Under the Influence of TH2 Cytokines

Undergraduate #13
Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology

Jelonia Rumph - Florida Memorial University
Co-Author(s): William Bracamonte-Baran and Daniela Cihakova, Johns Hopkins University, Baltimore, MD

Background: Recent studies have found that the cytokine IL-33 activates Th2 response via Innate Lymphoid Cells (ILCs). IL-33 also induces eosinophilic pericarditis and is involved in the pathology of autoimmune myocarditis. Furthermore, exogenous IL-33 induces its endogenous production by cardiac fibroblast (CFs). However, CFs do not have ST2, which is the surface receptor for IL-33. Aims/Hypothesis: This project aimed to investigate the role of CFs and innate lymphoid cells in a pro-inflammatory loop involved in pericarditis and myocarditis. In this loop we hypothesize: CF-derived IL-33 activates ILC type 2, resulting in the release of cytokines that can further activate CFs; in turn creating a pro-inflammatory cycle. Methods/Results: Sca1+ CFs were FACS sorted from mice hearts (WT Balb/c) and cultured in vitro for 6 days with focal ILC type 2-derived cytokines: IL5, IL9 and IL13. The readout of IL33 production was determined by ELISA, and the phenotype of CFs were analyzed through flow cytometry. A constitutive expression of IL33 by Sca1 CFs (27.55±1.35 pg/mL) was found. The production of IL-33 was not enhanced by IL5, IL9 or IL13 (29.30±1.20; 28.25±1.65; 33.2±2.90 pg/mL, respectively). Conclusion: The project showed that stimulation by IL-5, IL-9 and IL-13 were not the direct source of the release of IL-33 by CFs. As consequence, further investigation is required to determine if other ILC2-derived cytokine can stimulate CFs, or if another ST2+ cell, like mast cells, can mediate the ILC-CFs cross-talk.

Funder Acknowledgement(s): NHLBI RO1HL 118183; NHLBI RO1HL 113008; Catalyst Award JHU; American Autoimmune Related Diseases Association Inc.

Faculty Advisor: Marilyn Sherman, msherman@fmuniv.edu

Role: I performed the entire project on my own, but was overseen by William Bracamonte-Baran. My duties included sacrificing the mice by injecting them with an anesthetic and cervical dislocation. I also harvested and purified the heart and liver (centrifugation and lysis of RBCs) until pure cardiac fibroblasts were obtained. I then stained the samples with antibodies. I was also responsible for running the samples through flow cytometry and analyzing the results.