A lectin from Heliantus Annus recongizes GP120 from HIV-1 and promotes an inflammatory phenotype in dendritic cells

Abstract

Background: Helja is a mannose-binding lectin that is isolated fromsunflower seeds. HIV-1 envelope glycoprotein (gp120) containshigh-mannose and complex N-glycans. The aim of this study wasto analyze whether Helja recognizes gp120 and induces maturationand pro-inflammatory cytokine transcription in dendritic cells (BMDCs).Methods: Helja was purified from Helianthus annuus seedsusing D-mannose-agarose affinity chromatography. Molecular interactionsbetween Helja and recombinant gp120 were evaluatedby dot and ligand blot approaches using anti-Helja antibodies. BMDCswere cultured in complete RPMI medium supplemented withFLT3-L. Cell phenotype was evaluated in Helja-treated BMDCs bymeasuring membrane proteins (CD86, CD40, MHCII, CD11c, CD80,Clec9a, Ly6G, SIPRα, CD103 and SiglecH) by FACS. BMDCs cytokineprofiles were analyzed using RT-qPCR (il-6, tnf-α, il-12, inf-αtgf-b, and il-10). Results: Helja-gp120 interactions were measuredby immunodetection and confirmed by ligand blot assays. A signaldot was observed at a MW of 95 kDa. Next, BMDCs were stimulatedwith Helja (10 μg/ml) to evaluate cell activation. The lectin induced amarked upregulation of MHCII, MHCI, CD80, CD40 and CD86 (n=3,**p<0.01 Helja-treated BMDCs vs control, *p<0.05 Helja+LPS-treatedBMDCs vs LPS control). No changes in Clec9a, Ly6G, SIRPα,CD103 and SiglecH were detected. Finally, Helja also induced thetranscriptional activity of pro-inflammatory and antiviral cytokines(il-6, tnf-α, il-12 and inf-α (n=3, *p<0,05, **p<0,01, ***p<0,001 vscontrol) resulting in an additive effect with LPS. No increase in anti-inflammatory cytokines (tgf-b, il-10) was observed. Conclusions:Helja recognizes specific glycosidic residues and arrangements ofgp120 in HIV-1, which induces dendritic cell maturation. This promotesimmune activation, leading to the release of proinflammatorycytokines by BMDCs. These results suggest that this lectin has potentialbiomedical applications as an antiviral agent.