ANA BELEN ARROYO RODRIGUEZ¹, Eva Bastida Bastida Martínez², Antonio J Monera Girona², Joaquín Cantón Sandoval¹, Diana García Moreno¹, Montserrat Elías Arnanz², Victoriano Mulero Méndez¹

(1) INMUNIDAD, INFLAMACIÓN Y CÁNCER, IMIB-Arrixaca, España
(2) Departamento de Genética y Microbiología, Área de Genética, Facultad de Biología, Universidad de Murcia, España (Región de Murcia)

Plasmalogens (Pls) are glycerophospholipids with a hallmark vinyl ether bond that confers unique properties. Pls are present in numerous tissues, being abundant in the nervous, immune, and cardiovascular systems. Membrane organization, signaling, and antioxidant functions are attributed to these lipids. However, Pl functions remain enigmatic and are likely to be tissue and developmental stage specific. We recently discovered that Tmem189 is the long-sought enzyme responsible for incorporating the vinyl ether bond in a late step in Pl biosynthesis and demonstrated this activity for the two paralogs existing in zebrafish (1). This finding allows direct studies on Pls and their cellular functions in health and disease, which have thus far relied on targeting genes involved earlier in the biosynthetic pathway. Thus, we aim to evaluate the effects of tmem189 suppression in zebrafish embryos under normal and inflammatory conditions focusing on neutrophil activity.

Genetic inhibition of tmen189 was performed using CRISPR/Cas9 technology. The reduction of Pls levels was confirmed by mass spectrometry. Spint1a-/- zebrafish was used as a chronic skin inflammation model, which is characterized by neutrophil dispersion and skin aggregates. A tail wound was done as model of acute inflammation in both, spint1a-/- and WT larvae. Neutrophils dispersion and recruitment was evaluate by using tg(lyz:dsred) reporter at 3 and 5 days post-fertilization (dpf) and at 1, 3 and 6 hours post-wound (hpw), respectively.

Under normal conditions (WT larvae), Pls synthesis inhibition led to more neutrophil dispersion at 3 and 5dpf. Similarly, under chronic inflammation (spint1a-/- larvae), suppression of tmen189 increased neutrophil dispersion and worsened skin condition at both times points evaluated. In addition, the acute inflammation model revealed that the lack of Pls accelerated migration and recruitment of neutrophils to the injury site in a time-dependent manner.

Overall, our results suggest an important role of Pls in neutrophil biology and highlight the potential anti-inflammatory properties of these unique lipids. References 1. A. Gallego-Garcia et al., A bacterial light response reveals an orphan desaturase for human plasmalogen synthesis. Science 366, 128-132 (2019).