RESUMO
Bovine lactoferrin (bLf) confers significant functional benefits for human health, but low concentrations in milk and high cost of commercial production limit availability and thus product application. Precision fermentation offers a solution to increase availability of biosimilar recombinant bLf (rbLf) thereby opening new opportunities for this high-value ingredient. To comply with regulatory requirements, we aimed to establish that rbLf from K. phaffii is substantially similar to native bLf in structure and key functions. Intact mass analysis showed a molecular weight of 84 kDa for rbLf, comparable to 82-83 kDa of bLf. LC-MS N-linked glycan profiling revealed predominantly high-mannose-based glycans on rbLf, similar to ~50% of bLf glycans. The isoelectric point and core amino acid sequence of rbLf and bLf are identical. rbLf retains the functional ability to bind and release iron, bind to intestinal Lf receptors, increase epithelial cell growth (>120% of control, P < 0.0001), reduce EPEC growth (>50% reduction, P < 0.0001), bind LPS (+4 fold, P < 0.001) and antagonize LPS-induced TLR4 activity (>40% reduction, P < 0.0001). These results demonstrate similarity of rbLf in structure and function to native bLf, supporting the effective application for expanded market opportunities for infant and adult health.
RESUMO
On arrested neutrophils a focal adhesive cluster of ~200 high affinity (HA) ß2-integrin bonds under tension is sufficient to trigger Ca2+ flux that signals an increase in activation in direct proportion to increments in shear stress. We reasoned that a threshold tension acting on individual ß2-integrin bonds provides a mechanical means of transducing the magnitude of fluid drag force into signals that enhance the efficiency of neutrophil recruitment and effector function. Tension gauge tethers (TGT) are a duplex of DNA nucleotides that rupture at a precise shear force, which increases with the extent of nucleotide overlap, ranging from a tolerance of 54pN to 12pN. TGT annealed to a substrate captures neutrophils via allosteric antibodies that stabilize LFA-1 in a high- or low-affinity conformation. Neutrophils sheared on TGT substrates were recorded in real time to form HA ß2-integrin bonds and flux cytosolic Ca2+, which elicited shape change and downstream production of reactive oxygen species. A threshold force of 33pN triggered consolidation of HA ß2-integrin bonds and triggered membrane influx of Ca2+, whereas an optimum tension of 54pN efficiently transduced activation at a level equivalent to chemotactic stimulation on ICAM-1. We conclude that neutrophils sense the level of fluid drag transduced through individual ß2-integrin bonds, providing an intrinsic means to modulate inflammatory response in the microcirculation.