IL-17 Induction by ArtinM is Due to Stimulation of IL-23 and IL-1 Release and/or Interaction with CD3 in CD4+ T Cells

Adjuvant ArtinM favored the host immunity against Cryptococcus gattii infection in C57BL/6 mice

Aim: Cryptococcus gattii causes a severe fungal infection with high mortality rate among immunosuppressed and immunocompetent individuals. Due to limitation of current antifungal treatment, new immunotherapeutic approaches are explored. Methods: This study investigated an immunization strategy utilizing heat-inactivated C. gattii with ArtinM as an adjuvant. C57BL/6 mice were intranasally immunized with heat-killed C. gattii and ArtinM was administrated either before immunization or along with HK-C. gattii. Mice were infected with C. gattii and the efficacy of the immunization protocol was evaluated. Results: Mice that received ArtinM exhibited increased levels of IL-10 and relative expression of IL-23 in the lungs, reduced fungal burden and preserved tissue integrity post-infection. Conclusion: Adjuvant ArtinM improved immunization against C. gattii infection in C57BL/6 mice.

Nematicidal effect of a lectin preparation from Artocarpus heterophyllus (Moraceae) on larvae and adults of Haemonchus contortus

Haemonchus contortus is a hematophagous parasite that causes damage to ruminant production worldwide. This study reported the in vitro nematicidal effect of a lectin preparation (LP) isolated from Artocarpus heterophyllus seeds on larvae and adults of H. contortus. The protein extraction was in phosphate-buffered saline followed by protein precipitation with ammonium sulfate 70% and dialysis. The dialyzed protein fraction was chromatographed to obtain isolated LP. The LP was characterized by hemagglutinating activity (HA) assays, protein dosage and polyacrylamide gel electrophoresis. The motility index of H. contortus in the third larval stage (unsheathed L3 larvae) and adult stage was evaluated. The HA inhibition of LP by mannose and galactose as well as the electrophoretic profile indicated the presence of the lectins ArtinM and Jacalin. The motility index of H. contortus was significantly reduced (p < 0.001) during the first 8 h of LP exposure, both in larvae (lowest index 8.3% with LP at 1 mg mL-1) and female adults (lowest index 20% with LP at 500 μg mL-1; index 40% with LP at 1 mg mL-1). This research revealed that the LP has potential for being utilized in the development of natural nematicides.

Jackfruit (Artocarpus heterophyllus Lam.) in health and disease: a critical review

Artocarpus heterophyllus Lam. (Family Moraceae), is a tropical tree, native to India and common in Asia, Africa, and several regions in South America. The fruit is commonly known as jackfruit which is one of the largest edible fruits in the world. Jackfruits comprises a wide range of nutrients, including minerals, carbohydrates, volatile compounds, proteins, and vitamins. The fruit, bark, leaves, and roots are endowed with therapeutic attributes and are utilized in the many traditional medicinal systems for the management of various ailments. Fruit and seeds are commonly used to prepare various food items, including sauce, ice creams, jams, jellies, and marmalades. Due to unique texture, jackfruit is becoming a popular meat substitute. Based on preclinical studies, jackfruit exhibits antimicrobial, antioxidant, anti-melanin, antidiabetic, anti-inflammatory, immunomodulatory, antiviral, anthelmintic, wound-healing, and antineoplastic activities. Clinical studies reveal that the leaves possess antidiabetic action in healthy and insulin-independent diabetic individuals. Despite numerous health benefits, regrettably, jackfruit has not been properly utilized in a marketable scale in areas where it is produced. This review delivers an updated, comprehensive, and critical evaluation on the nutritional value, phytochemical profiling, pharmacological attributes and underlying mechanisms of action to explore the full potential of jackfruit in health and disease.

Echinacea purpurea L. (Moench) Hemagglutinin Effect on Immune Response In Vivo

Echinacea purpurea L. (Moench) is used in traditional and conventional medicine. However, there is lack of data on the biological activities of primary plant metabolite lectins. The aim of our experiment was to find out how lectin LysM (lysine motif), which was previously purified, affects the immune response in vivo. Eight-week-old BALB/c male mice (n = 15) received four weekly 250 μg/kg peritonial injections of purified Echinacea purpurea L. (Moench) roots’ LysM lectin. The control animal group (n = 15) received 50 μL peritoneal injections of fresh Echinacea purpurea L. (Moench) root tincture, and the negative control animal group (n = 15) received 50 μL peritoneal injections of physiological solution. At the fifth experimental week, the animals were sedated with carbon dioxide, and later euthanized by cervical dislocation, and then their blood and spleen samples were collected. The leukocytes’ formula and lymphocytes’ count was estimated in blood samples, the T lymphocytes’ density was evaluated in spleen zones. A statistically significant (p < 0.05) difference between each group was observed in the leukocytes’ formula (monocytes’ percentage, also little, medium and giant size lymphocytes). The purple coneflower fresh roots’ tincture significantly decreased (p < 0.05) the T lymphocytes’ quantity in peritoneal lymphoid sheaths (PALS) compared with the physiological solution injection’s group (p < 0.05) and the lectin injection’s group (p < 0.001). Meanwhile, lectin injections caused a significant (p < 0.01) increase in the T lymphocytes in a spleen PALS zone, compared with the physiological solution and tincture injection’s group. Our data suggests that LysM lectin acts as an immunostimulant, while fresh purple coneflower tincture causes immunosuppression.

The lectin ArtinM activates RBL-2H3 mast cells without inducing degranulation

Mast cells are connective tissue resident cells with morphological and functional characteristics that contribute to their role in allergic and inflammatory processes, host defense and maintenance of tissue homeostasis. Mast cell activation results in the release of pro-inflammatory mediators which are largely responsible for the physiological functions of mast cells. The lectin ArtinM, extracted from Artocarpus heterophyllus (jackfruit), binds to D-manose, thus inducing degranulation of mast cells. ArtinM has several immunomodulatory properties including acceleration of wound healing, and induction of cytokine release. The aim of the present study was to investigate the role of ArtinM in the activation and proliferation of mast cells. The rat mast cell line RBL-2H3 was used throughout this study. At a low concentration (0.25μg/mL), ArtinM induced mast cell activation and the release of IL-6 without stimulating the release of pre-formed or newly formed mediators. Additionally, when the cells were activated by ArtinM protein tyrosine phosphorylation was stimulated. The low concentration of ArtinM also activated the transcription factor NFkB, but not NFAT. ArtinM also affected the cell cycle and stimulated cell proliferation. Therefore, ArtinM may have therapeutic applications by modulating immune responses due to its ability to activate mast cells and promote the release of newly synthesized mediators. Additionally, ArtinM could have beneficial effects at low concentrations without degranulating mast cells and inducing allergic reactions.

Topical application of lectin Artin M improves wound healing in defects created in the palatal mucosa: an in vivo study in dogs

Previous studies have shown that topical application of lectin Artin-M accelerates wound healing in the rat oral mucosa. The aim of this study was to evaluate, by means of histology and immunohistochemistry (IHC) the effects of Artin-M on wound healing in the palatal mucosa in dogs. Three full thickness wounds of 6 mm diameter were surgically created in the palatal mucosa of twenty dogs and randomly divided into three groups according to one of the treatment assigned: Group C-Control (coagulum); Group A-Artin-M gel; Group V-Vehicle (carboxymethylcellulose 3%). Each animal received all the three experimental treatments. Afterwards, four animals were killed at 2, 4, 7, 14 and 21 days post-surgery. Wounded areas were photographed and scored for macroscopic evaluation. Biopsies were harvested and used for descriptive histological analysis, proliferating cell nuclear antigen IHC and measurement of myeloperoxidase activity. The results demonstrated faster wound closure in group A in comparison to the other groups in all the periods evaluated. Histological analyses exhibited improved re-epithelialization and collagen fiber formation resulting in faster maturation of granulation tissue in group A compared to the other groups by day 14. Treatment with Artin-M gel significantly induced cell proliferation and increased volumetric density of fibroblasts at day 2 and 4 (p < 0.05). Neutrophil infiltration in group A was significantly higher than the other groups (p < 0.05) at the same time points. Collectively, our findings demonstrated that Artin-M may potentially favor wound healing on palatal mucosa lesions via recruitment of neutrophils and promotion of cell proliferation.

ArtinM: Purification and Evaluation of Biological Activities

The immunomodulatory activity of plant lectins has been evaluated because of their high selectivity for glycans linked to receptors on innate and adaptative immune cells. ArtinM is a mannosyl-binding lectin, obtained from the seeds of Artocarpus heterophyllus, that induces the differentiation of CD4⁺ T cells and macrophages by interacting with CD3 and TLR2/CD14, respectively. This ArtinM property ultimately favors the combat of intracellular pathogens, opening new perspectives on the lectins application as immunomodulatory agents. The current section describes protocols for purification and evaluation of ArtinM biological activity. The purification is based on the ArtinM-D-mannose affinity. The effect of inducing IL-12 production by murine macrophages cell line is adopted to evaluate the ArtinM biological activity.

The Response of IL-17-Producing B Cells to ArtinM Is Independent of Its Interaction with TLR2 and CD14

ArtinM, a d-mannose-binding lectin from Artocarpus heterophyllus, activates antigen-presenting cells by recognizing Toll-like receptor (TLR)2 and cluster of differentiation (CD)14 N-glycans, induces cytokine production, and promotes type 1 T helper (Th1) immunity, a process that plays an assisting role in the combat against fungal infections. We recently demonstrated that ArtinM stimulates CD4⁺ T cells to produce interleukin (IL)-17 through direct interaction with CD3. Here, we further investigated the effects of ArtinM on the production of IL-17 by B cell activation. We showed that ArtinM activates murine B cells, increasing IL-17 and IL-12p40 production. The direct effect of ArtinM was sufficient to induce IL-17 production in B cells, and we did not find differences in the levels of IL-17 between the B cells purified from the wild-type (WT) and knockout (KO) mice for TLR2 or CD14 in the presence of ArtinM. Thus, the effects of ArtinM on splenic B cells through carbohydrate recognition may contribute to Th17 immunity; however, the mechanism involved is not associated with the interaction of ArtinM with TLR2 and CD14. The current work represents a pioneering effort in the understanding of the induction of IL-17 by lectins in B cells.

Developmental endothelial locus-1 (Del-1) antagonizes Interleukin-17-mediated allergic asthma

Interleukin (IL)-17 is a major contributor to the pathogenesis of allergic asthma. Developmental endothelial locus-1 (Del-1) is an endothelial cell-secreted protein known to inhibit IL-17 expression. However, little is known about the association between Del-1 and IL-17 in the pathogenesis of allergic asthma. Using bronchoalveolar lavage fluid (BALF) and peripheral blood samples collected from allergic asthmatic patients and controls, we explored the role of Del-1 in relation to IL-17 in allergic asthma. We found that the negative correlation between Del-1 and IL-17 was significant in BALF of allergic asthmatics. Del-1 treatment inhibited the expression of IL-17, the differentiation of IL-17-secreting leukocytes and associated cytokines. Contrarily, IL-17 levels were increased after treatment with anti-Del-1 mAb. Consistent with this, Del-1 treatment led to downregulation of IL-5, CCL5 and IL-4, thus reducing secretion of eosinophil cationic protein. Furthermore, Del-1 significantly downregulated the expression of ICAM-1 and may have the potential to reduce leukocyte transendothelial migration. Our data demonstrate that Del-1 can negatively regulate IL-17 and its proinflammatory function, thereby limiting airway inflammation in allergic asthmatics, and suggest Del-1 as a potential candidate for prevention and treatment of allergic asthma.

Targeting and Recognition of Toll-Like Receptors by Plant and Pathogen Lectins

We have reported that some lectins act as agonists of toll-like receptors (TLRs) and have immunomodulatory properties. The plant lectin ArtinM, for example, interacts with N-glycans of TLR2, whereas other lectins of microbial origin interact with TLR2 and TLR4. Expression of the receptors on the surface of antigen-presenting cells exposes N-glycans that may be targeted by lectins of different structures, specificities, and origins. In vitro, these interactions trigger cell signaling that leads to NF-κB activation and production of the Th1 polarizing cytokine IL-12. In vivo, a same sequence of events follows the administration of an active lectin to mice infected with an intracellular pathogen, conferring resistance to the pathogen. The lectins of the human pathogens Toxoplasma gondii (TgMIC1 and TgMIC4) and Paracoccidioides brasiliensis (Paracoccin), by recognition and activation of TLR2 and TLR4, induce cell events and in vivo effects comparable to the promoted by the plant lectin ArtinM. In this article, we highlight these two distinct mechanisms for activating antigen-presenting cells. On the one hand, TLRs act as sensors for the presence of conventional pathogen-associated molecular patterns, such as microbial lipids. On the other hand, we showed that TLR-mediated cell activation might be triggered by an alternative way, in which lectins bind to TLRs N-glycans and stimulate cells to increase the expression of pro-inflammatory cytokines. This process may lead to the development of new pharmaceutical tools that promote protective immune responses directed against intracellular pathogens and tumors.

Systemic effects in naïve mice injected with immunomodulatory lectin ArtinM

Toll-like receptors (TLR) contain N-glycans, which are important glycotargets for plant lectins, to induce immunomodulation. The lectin ArtinM obtained from Artocarpus heterophyllus interacts with TLR2 N-glycans to stimulate IL-12 production by antigen-presenting cells and to drive the immune response toward the Th1 axis, conferring resistance against intracellular pathogens. This immunomodulatory effect was demonstrated by subcutaneously injecting (s.c.) ArtinM (0.5 μg) in infected mice. In this study, we evaluated the systemic implications of ArtinM administration in naïve BALB/c mice. The mice were s.c. injected twice (7 days interval) with ArtinM (0.5, 1.0, 2.5, or 5.0 μg), LPS (positive control), or PBS (negative control) and euthanized after three days. None of the ArtinM-injected mice exhibited change in body weight, whereas the relative mass of the heart and lungs diminished in mice injected with the highest ArtinM dose (5.0 μg). Few and discrete inflammatory foci were detected in the heart, lung, and liver of mice receiving ArtinM at doses ≥2.5 μg. Moreover, the highest dose of ArtinM was associated with increased serum levels of creatine kinase MB isoenzyme (CK-MB) and globulins as well as an augmented presence of neutrophils in the heart and lung. IL-12, IFN-γ, TNF-α, and IL-10 measurements in the liver, kidney, spleen, heart, and lung homogenates revealed decreased IL-10 level in the heart and lung of mice injected with 5.0 μg ArtinM. We also found an augmented frequency of T helper and B cells in the spleen of all ArtinM-injected naïve mice, whereas the relative expressions of T-bet, GATA-3, and ROR-γt were similar to those in PBS-injected animals. Our study demonstrates that s.c. injection of high doses of ArtinM in naïve mice promotes mild inflammatory lesions and that a low immunomodulatory dose is innocuous to naïve mice.

ArtinM Mediates Murine T Cell Activation and Induces Cell Death in Jurkat Human Leukemic T Cells

The recognition of cell surface glycans by lectins may be critical for the innate and adaptive immune responses. ArtinM, a d-mannose-binding lectin from Artocarpus heterophyllus, activates antigen-presenting cells by recognizing TLR2 N-glycans and induces Th1 immunity. We recently demonstrated that ArtinM stimulated CD4⁺ T cells to produce proinflammatory cytokines. Here, we further studied the effects of ArtinM on adaptive immune cells. We showed that ArtinM activates murine CD4⁺ and CD8⁺ T cells, augmenting their positivity for CD25, CD69, and CD95 and showed higher interleukin (IL)-2 and interferon (IFN)-γ production. The CD4⁺ T cells exhibited increased T-bet expression in response to ArtinM, and IL-2 production by CD4⁺ and CD8⁺ T cells depended on the recognition of CD3εγ-chain glycans by ArtinM. The ArtinM effect on aberrantly-glycosylated neoplastic lymphocytes was studied in Jurkat T cells, in which ArtinM induced IL-2, IFN-γ, and IL-1β production, but decreased cell viability and growth. A higher frequency of AnnexinV- and propidium iodide-stained cells demonstrated the induction of Jurkat T cells apoptosis by ArtinM, and this apoptotic response was reduced by caspases and protein tyrosine kinase inhibitors. The ArtinM effects on murine T cells corroborated with the immunomodulatory property of lectin, whereas the promotion of Jurkat T cells apoptosis may reflect a potential applicability of ArtinM in novel strategies for treating lymphocytic leukemia.

Data on IL-17 production induced by plant lectins

We reported in article da Silva et al. (2016) [2] that ArtinM induces the IL-17 production through interaction with CD4⁺ T cells and stimulation of IL-23 and IL-1. Besides ArtinM, other plant lectins (PLs) induce IL-17 production by murine spleen cells. The IL-17 production induced by PLs was evaluated regarding the involvement of IL-23, IL-6, Th1-, and Th2-cytokines. Furthermore, the effect exerted TLR2, TLR4, and CD14 on the PLs׳ performance in the induction of IL-17 was examined. The current data were compared to the known ArtinM ability to induce Th17 immunity.