Immunomodulatory Effects of the Water-soluble Lectin from Moringa oleifera Seeds (WSMoL) on Human Peripheral Blood Mononuclear Cells (PBMC).

BACKGROUND: Moringa oleifera is used in traditional medicine as well as in food, cosmetic, and pharmaceutical industries. Water-soluble M. oleifera lectin (WSMoL) is an anionic protein isolated from the seeds of this tree. Until now, immune responses promoted by this lectin in human PBMC have not been investigated. OBJECTIVE: The main objective of this study was to investigate the immunomodulatory effects of WSMoL on human PBMC through measurement of lymphocytes subsets, cytokine and nitric oxide levels. METHODS: Human peripheral blood mononuclear cells (PBMC) were isolated through Ficoll technique, were incubated with WSMoL (10 µg/mL) for 24, 48 and 72 hours, and was performed immunophenotyping assay of lymphocytes and monocytes. Culture supernatants were used to determined cytokine and nitric oxide levels. Assays with cells subsets and cytokine production were performed through cytometry. Nitric oxide release assay was determinate by spectrophotometry. RESULTS: WSMoL induced the release of the cytokines TNF-α, IL-2, IL-6, IL-10 as well as nitric oxide. Incubation of PBMC with this lectin also led to activation of CD8+ T lymphocytes. CONCLUSION: WSMoL promotes immunomodulation in human PBMC inducing a potential wound healing profile and, in future in vivo assays, can be evaluated as adjuvant in immunosuppressive diseases and wound repair.

Lectin from inflorescences of ornamental crop Alpinia purpurata acts on immune cells to promote Th1 and Th17 responses, nitric oxide release, and lymphocyte activation.

Alpinia purpurata is an ornamental crop known as a source of bioactive molecules. This is the first study to report isolation of a lectin (carbohydrate-binding protein) from A. purpurata inflorescences (ApuL). The immunomodulatory potential of ApuL was evaluated by investigating its effects on the production of cytokines and release of nitric oxide by human peripheral blood mononuclear cells (PBMCs). In addition, the differentiation and activation of lymphocytes treated with ApuL was evaluated by immunophenotyping assays. ApuL is an acidic and oligomeric protein with native molecular mass of 34kDa. The hemagglutinating activity (HA) of ApuL was inhibited by the glycoproteins fetuin and ovalbumin, was resistant to heating at 100°C and stimulated in the presence of calcium and magnesium ions. ApuL showed highest HA at pH 7.5 but failed to agglutinate erythrocytes at pH 8.0 and 9.0. ApuL induced the release of cytokines belonging to Th1 (IFN-γ, TNF-α, and IL-6) and Th17 (IL-17A) profiles as well as of nitric oxide, stimulating a pro-inflammatory environment. Moreover, ApuL also stimulated the production of IL-10, an anti-inflammatory cytokine with regulatory role. Incubation with lectin resulted in differentiation and activation of both T CD8+ and CD4+ subsets of lymphocytes, as evident from the expression of the CD28 costimulatory molecule. In conclusion, A. purpurata inflorescence is a source of an immunomodulatory lectin with potential immunoregulatory application, thereby adding biotechnological value to this ornamental crop.

Microgramma vacciniifolia (Polypodiaceae) fronds contain a multifunctional lectin with immunomodulatory properties on human cells.

In this study, we report the purification and characterization of a multifunctional lectin (MvFL) from Microgramma vacciniifolia fronds as well as its immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). MvFL (pI 4.51; 54kDa) is a glycoprotein able to inhibit trypsin activity and that has sequence similarities (32% coverage) with a plant RNA-binding protein. Hemagglutinating activity of MvFL was not altered by heating at 100°C for 30min, but was reduced in alkaline pH (8.0 and 9.0). Fluorimetric analyses showed that this lectin did not undergo marked conformational changes when heated. However, the MvFL conformation changed depending on the pH. MvFL at 6.25-25µg/mL was not cytotoxic to lymphocytes present among PBMCs. The PBMCs incubated for 24h with the lectin (12.5µg/mL) showed increased TNF-α, IFN-γ, IL-6, IL-10, and nitric oxide production. MvFL also stimulated T lymphocytes from PBMCs to differentiate into CD8+ cells. The activation (indicated by CD28 expression) of these cells was also stimulated. In conclusion, MvFL is a heat-stable and multifunctional protein, with both lectin and trypsin inhibitor activities, and capable of inducing predominantly a Th1 response in human PBMCs as well as activation and differentiation of T lymphocytes.