Does the production of NF-ĸβ, IRF3, and IFN-β after LOS/LPS exposures in naive-HIV dendritic cells depend on TLR4-MD2 receptor pathway? In vitro and in silico study

Lipopolysaccharide (LPS) and lipooligosaccharide (LOS) are inflammatory response inducers triggering downstream inflammatory signals by binding to the TLR4-MD2 complex. LPS/LOS exposure through TLR4 receptor on dendritic cells (DC) causes an increase in interferon (IFN)-β expression via an increase in interferon regulatory factor (IRF)3 expression and a decrease in nuclear factor (NF)-ĸβ, which result in HIV replication inhibition. This study aimed to compare the binding affinity between Escherichia coli LPS and Neisseria gonorrhoeae LOS toward TLR4-MD2 in silico and the production of NF-ĸβ, IRF3, and IFN-β from naive-HIV monocyte-derived dendric cells (MDDCs) after LPS and LOS exposure in vitro, to find a deeper understanding of host immune response, disease pathogenesis, and trends of drug development in the future. Molecular docking and dynamics were analyzed using AutoDock Vina and YASARA, respectively. The naive-HIV DC culture was exposed to LPS at 50, 100, and 200 ng/mL, or LOS at concentrations of 2.5, 5, and 10% for 24-h. Levels of NF-ĸβ, IRF3, and IFN- β were measured by Enzyme-linked Immunosorbent Assay (ELISA). The results showed that LOS demonstrated higher binding affinity to TLR4-MD2 complex than LPS, although the docking between LOS and TLR4-MD2 complex involved fewer amino acids. Inversely, LPS exposure significantly increased IRF3 and IFN-β production (P < 0.01). Production of IFN-β was significantly increased with higher doses of LOS (P < 0.01). Different doses of LPS induced significant differences in NF-ĸβ and IFN-β levels (P < 0.01 and P < 0.05, respectively). Despite LOS showing higher binding affinity to TLR4-MD2 complex, LPS exposure induced higher production of IRF3 and IFN-β from MDDCs. These findings provided information for deeper apprehension of immune responses and disease pathogenesis during HIV co-infections.