Immunomodulatory role of Sphingosine Kinase 1 (SK1) on Triiodothyronine (T3)-matured Dendritic Cells (DC) and the driven adaptive response

NEGRETTI BORGA, DM; BLANCO A; TEIXEIRA MP; ALAMINO VA; SOLER MF; PUENTES EN; DONADIO AC; CLARK CJ; MONTESINOS MM; HANNUN Y; PELLIZAS CG

Mar del Plata

Congreso; LXVII Reunión Anual de la Sociedad de Investigación Clínica (SAIC); 2022

SAIC

Our group demonstrated that T3 generates adaptive proinflammatory and cytotoxic responses through DC activation, restraining regulatory signals. This protocol was successfully exploited in T3-stimulated DC (T3-DC)-based antitumor vaccines. T3 effects are mainly triggered by non-genomic mechanisms involving thyroid hormone receptor, Akt and NF-kB. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid produced by Sphingosine Kinase 1 (SK1) and 2. Although this pathway is involved in many proinflammatory conditions, little is known about its role in innate immune cells. We aim at evaluating the role of SK1 in T3-DC, and the driven adaptive immunity. Bone marrow DC were obtained from C57BL/6 WT or SK1KO mice and stimulated (or not) with T3 (10nM). PF-543 (SK1 inhibitor) was added, and 30 min later the T3 stimuli (PF-T3-DC). After 30 min, p-Akt/total Akt was analyzed by Western Blot. Allogenic splenocytes isolated from BALB/c mice were co-cultured with T3-DC (exposed to T3 for 18h), for 3 days. Viability and proliferation were evaluated by FACS. Cytokines were measured by FACS and ELISA. Statistical analysis: Two-way ANOVA/Tukey test, and paired t test. p<0.05, statistically significant. Results showed that intracellular IL-12 production was increased in T3-DC (18h T3 exposure) from SK1KO mice (vs WT, p< 0.0001). In accordance, IL-12 secretion was higher in PF-T3-DC (vs T3-DC, p< 0.005). Of note, DC viability was not modified by PF-543. In turn, SK1 inhibition reduced p-Akt in T3-DC (p< 0.005). IFN-γ and IL-17 production and secretion, as well as splenocytes proliferation, were modified in the co-culture with PF-T3-DC (vs. T3-DC, p<0.05). Our results revealed for the first time that the Sphingolipid intracellular pathway is involved in T3-DC activation. The immunomodulation exerted by SK1 on T3-DC and the driven adaptive response disclose a novel role of Sphingolipids in the immune-endocrine crosstalk. Further research would unveil the intimate signaling process.