ArtinM Cytotoxicity in B Cells Derived from Non-Hodgkin's Lymphoma Depends on Syk and Src Family Kinases.

Receptors on the immune cell surface have a variety of glycans that may account for the immunomodulation induced by lectins, which have a carbohydrate recognition domain (CRD) that binds to monosaccharides or oligosaccharides in a specific manner. ArtinM, a D-mannose-binding lectin obtained from Artocarpus heterophyllus, has affinity for the N-glycans core. Immunomodulation by ArtinM toward the Th1 phenotype occurs via its interaction with TLR2/CD14 N-glycans on antigen-presenting cells, as well as recognition of CD3γ N-glycans on murine CD4+ and CD8+ T cells. ArtinM exerts a cytotoxic effect on Jurkat human leukemic T-cell line and human myeloid leukemia cell line (NB4). The current study evaluated the effects of ArtinM on murine and human B cells derived from non-Hodgkin's lymphoma. We found that murine B cells are recognized by ArtinM via the CRD, and the ArtinM stimulus did not augment the proliferation rate or production of IL-2. However, murine B cell incubation with ArtinM augmented the rate of apoptosis, and this cytotoxic effect of ArtinM was also seen in human B cell-lines sourced from non-Hodgkin's lymphoma Raji cell line. This cytotoxic effect was inhibited by the phosphatase activity of CD45 on Lck, and the protein kinases of the Src family contribute to cell death triggered by ArtinM.

Saline extract from Malpighia emarginata DC leaves showed higher polyphenol presence, antioxidant and antifungal activity and promoted cell proliferation in mice splenocytes.

Currently, the research of new natural compounds with biological potential demonstrates great ethnopharmacological importance. In this study, we evaluated the biological properties promoted by saline extract from Malpighia emarginata DC leaves, whose objective is to evaluate the antioxidant, antimicrobial and cytotoxicity potential. Phytochemical characterization was performed by UPLC-MS chromatography to identify the chemical compounds. For the antioxidant potential, DPPH, ATT and FRAP methods were used. The antibacterial and antifungal tests were performed evaluating the MIC50, MIC90, CMB and CMF parameters. Moreover, antibiofilm action was evaluated. Cytotoxicity and proliferation were performed using splenocytes from Balb/c mice and were evaluated by cytometry. We found a list of phenolic compounds among other bioactive compounds in the M. emarginata saline extract. In addition, higher antioxidant profile and antifungal activity against different strains of Candida spp. was promoted by the saline extract. Splenocytes showed greater cell viability (more than 90%) and showed higher proliferate index in 24 and 48 hours of incubation with the extract. Saline extract from Malpighia emarginata DC has potential action like antioxidant and antifungal agent without promote animal cell damage.

Protein Arginylation Is Regulated during SARS-CoV-2 Infection.

BACKGROUND: In 2019, the world witnessed the onset of an unprecedented pandemic. By February 2022, the infection by SARS-CoV-2 has already been responsible for the death of more than 5 million people worldwide. Recently, we and other groups discovered that SARS-CoV-2 infection induces ER stress and activation of the unfolded protein response (UPR) pathway. Degradation of misfolded/unfolded proteins is an essential element of proteostasis and occurs mainly in lysosomes or proteasomes. The N-terminal arginylation of proteins is characterized as an inducer of ubiquitination and proteasomal degradation by the N-degron pathway. RESULTS: The role of protein arginylation during SARS-CoV-2 infection was elucidated. Protein arginylation was studied in Vero CCL-81, macrophage-like THP1, and Calu-3 cells infected at different times. A reanalysis of in vivo and in vitro public omics data combined with immunoblotting was performed to measure levels of arginyl-tRNA-protein transferase (ATE1) and its substrates. Dysregulation of the N-degron pathway was specifically identified during coronavirus infections compared to other respiratory viruses. We demonstrated that during SARS-CoV-2 infection, there is an increase in ATE1 expression in Calu-3 and Vero CCL-81 cells. On the other hand, infected macrophages showed no enzyme regulation. ATE1 and protein arginylation was variant-dependent, as shown using P1 and P2 viral variants and HEK 293T cells transfection with the spike protein and receptor-binding domains (RBD). In addition, we report that ATE1 inhibitors, tannic acid and merbromine (MER) reduce viral load. This finding was confirmed in ATE1-silenced cells. CONCLUSIONS: We demonstrate that ATE1 is increased during SARS-CoV-2 infection and its inhibition has potential therapeutic value.

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.