Periodic Reporting for period 1 - InRegen (Fine-tuning the inflammatory response following cardiac injury to promote cardiac regeneration)
Reporting period: 2021-03-15 to 2023-03-14
Myocardial infarction-related heart failure is a major cause of high mortality. Innate immunity, specifically macrophages and neutrophils, plays a crucial role in heart injury, scar regression, and regeneration. Neutrophils are among the first immune cells recruited to the site of injury, where they clear debris and release molecules that attract macrophages. Macrophages are also involved clearing dead cells, promoting angiogenesis and tissue repair, and contributing to fibrotic tissue formation. Macrophages communicate with other cells through various secreted molecules, including cytokines, chemokines, and extracellular vesicles, which influence recipient cell behaviour. Achieving a balance between innate immunity activation and resolution is crucial for cardiac tissue repair and preventing excessive inflammation and tissue damage. Zebrafish, known for its regenerative abilities, provides a model for studying heart regeneration. Upon heart injury, zebrafish exhibit a controlled inflammatory response involving macrophages and neutrophils, which clear damaged tissue and promote regeneration. Understanding the mechanisms underlying heart regeneration in zebrafish may provide insights for potential therapeutic strategies heart failure.
Therefore we established a cross-species platform in which we can investigate the impact of macrophages and neutrophils from non-regenerative mammals on the zebrafish heart regeneration abilities. We isolate macrophages or neutrophils from mouse and polarize them into pro-inflammatory (M1/N1) or pro-regenerative (M2/N2) states in vitro. We then incubate the conditioned media from these cells with ex vivo regenerating zebrafish hearts and analysed the effects of the conditioned media on cell proliferation. When we incubated zebrafish hearts with neutrophils conditioned media, we did not observe any effect on cell proliferation. However, M1 conditioned media decreased cell proliferation, while M2 conditioned media increased it. Through secretome analysis of M1 and M2 conditioned media; we discovered distinct patterns of molecular expression. These patterns suggest their roles in immune function, scarring, gene expression control, and cellular processes related to cell proliferation, structural rearrangements, and morphological adaptations.
Our study investigates the impact of innate immunity from non-regenerative mammals on zebrafish heart regeneration. Our findings indicate that pro-inflammatory and pro-regeneration macrophages have differential effects on cell proliferation during zebrafish heart regeneration. This study provides insights into the molecular cues involved in heart regeneration and may contribute to the development of therapeutic strategies for promoting heart regeneration in humans.