Oral administration of insulin receptor-interacting lectins leads to an enhancement in the hematopoietic stem and progenitor cell pool of mice

Lectins form an important constituent of our daily diet, and thus, it is essential that their effect(s) on various tissues be examined systematically in order to assess whether they are beneficial or detrimental to human health. We examined the effect of oral administration of two dietary lectins that were isolated from banana (BL) and garlic (GL)-two quite commonly consumed food items-on the hematopoiesis of mice. Balb/c mice were fed weekly with lectins and their marrow mononuclear cells (MNCs) were subjected to various hematopoietic stem/progenitor (HSPC)-specific phenotypic and functional assays. It was observed that the lectin-fed mice harbored a considerably increased HSPC pool in their marrow. Marrow-derived MNCs isolated from these lectin-fed mice gave rise to large-sized colony-forming unit-fibroblast (CFU-F) colonies indicating that the lectins had a salutary effect on the stromal compartment. The molecular mechanisms involved in the process were examined by using a stromal cell line model, M210B4. The lectins pulled down pro-insulin and insulin receptors in an immunoprecipitation experiment and activated extracellular signal-regulated kinase (ERK) signaling in the treated cells, in a manner comparable to insulin, both in terms of kinetics as well as extent. M210B4 cells incubated with BL, GL, or insulin showed reduced levels of reactive oxygen species, suggesting that perhaps the lectins protected the stem cell pool of mice by activating ERK signaling and reducing the oxidative stress in the niche. Our data suggest that these lectins may serve as micronutrients for therapeutic purposes in hematological deficiencies