Polymeric mannosides prevent DC-SIGN-mediated cell-infection by cytomegalovirus.

Human cytomegalovirus (HCMV) is a beta-herpesvirus with a high prevalence in the population. HCMV is asymptomatic for immunocompetent adults but is a leading cause of morbidity for new born and immunocompromised patients. It was recently shown that the envelope glycoprotein B (gB) of HCMV interacts with the Dendritic Cell-Specific ICAM-3 Grabbing Non integrin (DC-SIGN) to infect the host. In this work we developed a set of DC-SIGN blockers based on mono-, di-, tetra and polyvalent mannosides. The multivalent mannosides were designed to interact with the carbohydrate recognition domains of DC-SIGN in a chelate or bind and recapture process, and represent the first chemical antiadhesives of HCMV reported so far. Polymeric dextrans coated with triazolylheptylmannoside (THM) ligands were highly potent, blocking the gB and DC-SIGN interaction at nanomolar concentrations. The compounds were further assessed for their ability to prevent the DC-SIGN mediated HCMV infection of dendritic cells. A dextran polymer coated with an average of 902 THM ligands showed an outstanding effect in blocking the HCMV trans-infection with IC50 values down to the picomolar range (nanomolar when expressed in THM concentration). Each THM moiety on the polymer surpassed the antiadhesive effect of the methylmannoside reference by more than four orders of magnitude. The compound proved non-cytotoxic at the high concentration of 2 mM and therefore represents an interesting antiadhesive candidate against HCMV and potentially against other virus hijacking dendritic cells to infect the host.

Second generation of thiazolylmannosides, FimH antagonists for E. coli-induced Crohn's disease.

The anti-adhesive strategy, consisting of disrupting bacterial attachment to the host cells, is widely explored as an alternative to antibiotic therapies. Recently, thiazolylmannosides (TazMans) have been identified as strong anti-adhesives of E. coli strains implied in the gut inflammation of patients with Crohn's disease. In this work, we developed a second generation of TazMans with improved chemical stability. The anomeric nitrogen was substituted by short linkers and the compounds were assessed against the bacterial adhesin FimH and the clinically isolated LF82 E. coli strain in four in vitro assays. The results obtained on the FimH adhesin alone and the whole bacteria enabled the identification of a candidate for further in vivo evaluations.

Inhibition profiles of mono- and polyvalent FimH antagonists against 10 different Escherichia coli strains.

Mono- and polyvalent ligands with strong affinities for the mannose-binding adhesin FimH were synthesised, and their anti-adhesive properties against ten E. coli strains were compared in two cell-based assays. The compounds were assessed against the non-pathogenic E. coli K12 and nine strains isolated by coproculture or from patients with osteoarticular infections (OIs), Crohn's disease (CD) and urinary tract infections (UTIs). The results showed that the compounds could inhibit the whole set of bacterial strains but with marked differences in terms of effective concentrations. The relative inhibitory potency of the monovalent compounds was also conserved for the ten strains and in the two assays. These results clearly suggest that a potent monovalent anti-adhesive assessed on a single E. coli strain will probably be effective on a broad range of strains and may treat diverse E. coli infections (OIs, CD and UTIs). In contrast, the polyvalent compounds showed a significant strain-dependancy in preventing E. coli attachment to intestinal cells. The multivalent antiadhesive effect may therefore vary depending on the E. coli strain tested.