Synthesis of polyfluoroalkyl sp2-iminosugar glycolipids and evaluation of their immunomodulatory properties towards anti-tumor, anti-leishmanial and anti-inflammatory therapies

Immunomodulatory glycolipids, among which α-galactosylceramide (KRN7000) is an iconic example, have shown strong therapeutic potential in a variety of conditions ranging from cancer and infection to autoimmune or neurodegenerative diseases. A main difficulty for those channels is that they often provoke a cytokine storm comprising both pro- and anti-inflammatory mediators that antagonize each other and negatively affect the immune response. The synthesis of analogues with narrower cytokine secretion-inducing capabilities is hampered by the intrinsic difficulty at controlling the stereochemical outcome in glycosidation reactions, particularly if targeting the α-anomer, which seriously hampers drug optimization strategies. Here we show that replacing the monosaccharide glycone by a sp-iminosugar glycomimetic moiety allows accessing N-linked sp-iminosugar glycolipids (sp-IGLs) with total α-stereocontrol in a single step with no need of protecting groups or glycosidation promotors. The lipid tail has been then readily tailored by incorporating polyfluoroalkyl segments of varied lengths in view of favouring binding to the lipid binding site of the master p38 mitogen activated protein kinase (p38 MAPK), thereby polarizing the immune response in a cell-context dependent manner. The compounds have been evaluated for their antiproliferative, anti-leishmanial and anti-inflammatory activities in different cell assays. The size of the fluorous segment was found to be critical for the biological activity, probably by regulating the aggregation and membrane-crossing properties, whereas the hydroxylation profile (gluco or galacto-like) was less relevant. Biochemical and computational data further support a mechanism of action implying binding to the allosteric lipid binding site of p38 MAPK and subsequent activation of the noncanonical autophosphorylation route. The ensemble of results provide a proof of concept of the potential of sp-IGLs as immunoregulators.This work was supported by grants from the Spanish Ministry of Economy and Competitiveness/Ministry of Science, Education and Universities: SAF2016-76083-R (MINECO-FEDER), RTI2018-097210-B-I00 (MINCIU-FEDER) to FG, CTQ2015-64425-C2-1-R (MINECO-FEDER) and RTI2018-097609-B-C21 (MINCIU-FEDER). JMP thanks the Spanish Government for financial support through project PGC2018-094503-B-C22 (MINCIU-/AEI/FEDER, UE). Technical assistance from the research support services of the University of Seville (CITIUS) is also acknowledged. A.I.A. supported this work by grants from Instituto de Salud Carlos III (PI18/01287) and Consejería de Salud de la Junta de Andalucía (PI-0123-2018). MAD supported this work by grants from Convocatoria de subvenciones para la financiación de la investigación y la innovación biomédica y en Ciencias de la Salud en el marco de la iniciativa territorial integrada 2014–2020 para la provincia de Cádiz, Fondos ITI-FEDER (PI-0029-2017) and from Instituto de Salud Carlos III (PI18/01287)