Insulin potentiates FcepsilonRI-mediated signaling in mouse bone marrow-derived mast cells

Network Pharmacology- and Molecular Dynamics Simulation-Based Bioprospection of Aspalathus linearis for Type-2 Diabetes Care

The medicinal herb Aspalathus linearis (rooibos) is globally recognized in type-2 diabetes mellitus (T2DM) treatment due to its known and distinctive compounds. This work utilized network pharmacology (NP) coupled with molecular dynamics simulation in gaining new insight into the anti-diabetic molecular mechanism of action of rooibos teas. It looked at the interactions between rooibos constituents with various relevant protein receptors and signaling routes associated with T2DM progression. The initial analysis revealed 197 intersecting gene targets and 13 bioactive rooibos constituents linked to T2DM. The interactions between proteins and compounds to the target matrix were generated with the Cystoscope platform and STRING database. These analyses revealed intersecting nodes active in T2DM and hypoxia-inducible factor 1 (HIF-1) as an integral receptors target. In addition, KEGG analysis identified 11 other pathways besides the hub HIF-1 signaling route which may also be targeted in T2DM progression. In final molecular docking and dynamics simulation analysis, a significant binding affinity was confirmed for key compound-protein matrices. As such, the identified rooibos moieties could serve as putative drug candidates for T2DM control and therapy. This study shows rooibos constituents' interaction with T2DM-linked signaling pathways and target receptors and proposes vitexin, esculin and isovitexin as well as apigenin and kaempferol as respective pharmacologically active rooibos compounds for the modulation of EGFR and IGF1R in the HIF-1 signaling pathway to maintain normal homeostasis and function of the pancreas and pancreatic β-cells in diabetics.

A network pharmacology study to investigate bioactive compounds and signaling pathways of garlic (Allium sativum L.) husk against type 2 diabetes mellitus

During garlic harvest, much husk has been generated, nearly all husk is discarded as unnecessary by-products. However, in Korean folk remedies, Allium sativum L. husk (ASLH) extracts have been used as a reliever against type 2 diabetes mellitus (T2DM). Currently, its significant mechanisms against T2DM remain unclear. Thus, the aim of this study is to investigate the characteristics of its key signaling pathways, targets, and compounds. The compounds in ASLH were analyzed by gas chromatography-mass spectrum (GC-MS) and confirmed drug-like compounds (DLCs) in silico. Then, protein-protein interaction (PPI) networks and signaling pathways, targets, compounds are constructed, visualized by using RStudio. Finally, we performed a molecular docking test (MDT) to identify the key mechanism(s), target(s), and compound(s) of ASLH on T2DM. A total of 23 compounds in ASLH were identified by GC-MS, and all compounds were accepted by Lipinski's rule. The 23 compounds were associated with 521 targets and retrieved 4,736 T2DM-related targets by Online Mendelian Inheritance in Man (OMIM) and DisGeNET. The final overlapping 87 targets were obtained between compounds-targets and T2DM-related targets. The number of 13 signaling pathways, 33 targets, and 19 compounds of ASLH were associated with T2DM. In parallel, MDT revealed four potential compounds: (1) 9-hexacosene, (2) 2-(([2-ethylhexyl]oxy)carbonyl)benzoic acid, (3) clionasterol, (4) 4-methyl-2-phenylpyrimidine on PPAR signaling pathway. Overall, the four compounds from ASLH might show an anti-T2DM synergistic effect by activating the PPAR signaling pathway or inactivating the phospholipase D signaling pathway. In this study, we suggest that ASLH might be considered a health-promising resource from both nutraceutical and pharmaceutical perspectives. PRACTICAL APPLICATIONS: Allium sativum L. husk (ASLH) has been regarded as wastes that come from garlic (Allium sativum L.). During the harvesting period of garlic, a considerable amount of ASLH is a severe problem in farm communities. Particularly, garlic bioactive compounds are well documented including organosulfur compounds. Conversely, at present, no information is available on chemical compounds of ASLH to use in health industries. Taking this matter into consideration, our analysis approach was to select drug-like compounds (DLCs) from ASLH via GC-MS, thereby we can explore the compounds with high cell permeability. The screened compounds can be used as nutraceutical or medicinal or even cosmetical resources. In this study, we described the significant compounds via the network pharmacology concept to uncover the pharmaceutical mechanism(s) of ASLH against T2DM. Eventually, this work provides nutraceutical or medicinal value of ASLH and suggests that ASLH might be used as an upcycling resource to relieve T2DM.

The regulatory role of insulin in energy metabolism and leukocyte functions

Insulin is the hormone responsible for maintaining glucose homeostasis in the body, in addition to participating in lipid metabolism, protein synthesis, and the inhibition of gluconeogenesis. These functions are well characterized in the classic organ target cells that are responsible for general energy regulation: the liver, skeletal muscle, and adipose tissue. However, these actions are not restricted to these tissues because insulin has been shown to affect most cells in the body. This review describes the role of insulin in leukocyte signaling pathways, metabolism and functions, and how insulin resistance could affect this signaling and deteriorate leukocyte metabolism and function, in addition to showing evidence that suggests leukocytes may substantially contribute to the development of systemic insulin resistance.

Network pharmacology of bioactives from Sorghum bicolor with targets related to diabetes mellitus

BACKGROUND

Sorghum bicolor (SB) is rich in protective phytoconstituents with health benefits and regarded as a promising source of natural anti-diabetic substance. However, its comprehensive bioactive compound(s) and mechanism(s) against type-2 diabetes mellitus (T2DM) have not been exposed. Hence, we implemented network pharmacology to identify its key compounds and mechanism(s) against T2DM.

METHODS

Compounds in SB were explored through GC-MS and screened by Lipinski's rule. Genes associated with the selected compounds or T2DM were extracted from public databases, and the overlapping genes between SB-compound related genes and T2DM target genes were identified using Venn diagram. Then, the networking between selected compounds and overlapping genes was constructed, visualized, and analyzed by RStudio. Finally, affinity between compounds and genes was evaluated via molecular docking.

RESULTS

GC-MS analysis of SB detected a total of 20 compounds which were accepted by the Lipinski's rule. A total number of 16 compounds-related genes and T2DM-related genes (4,763) were identified, and 81 overlapping genes between them were selected. Gene set enrichment analysis exhibited that the mechanisms of SB against T2DM were associated with 12 signaling pathways, and the key mechanism might be to control blood glucose level by activating PPAR signaling pathway. Furthermore, the highest affinities were noted between four main compounds and six genes (FABP3-Propyleneglyco monoleate, FABP4-25-Oxo-27-norcholesterol, NR1H3-Campesterol, PPARA-β-sitosterol, PPARD-β-sitosterol, and PPARG-β-sitosterol).

CONCLUSION

Our study overall suggests that the four key compounds detected in SB might ameliorate T2DM severity by activating the PPAR signaling pathway.

A rapid, multiplexed kinase activity assay using 8-plex iTRAQ labeling, SPE, and MALDI-TOF/TOF MS

Synthesized peptide substrates have been used for in vitro phosphorylation using purified kinases or cell lysates. For screening assays, a direct readout and comparison among different experimental conditions without using an internal standard would be preferred. In this study, we developed a rapid, quantitative measurement method of multikinase activity based on MALDI-TOF/TOF MS. We combined 8-plex iTRAQ-labeled peptide substrates, solid phase extraction (SPE), and a phosphorylated peptide purification plate to rapidly determine multikinase activity in cell lysates. To enable our platform to be applicable in insulin stimulation and cancer drug inhibition, a list of peptide substrates was designed. By labeling peptide substrates with 8-plex iTRAQ reagents, protein kinase activity in 8 samples could be directly compared using the mass tags on their fragmented ion spectra. The protein amount and incubation time for multikinase activity assays were optimized, and the effect of insulin stimulation and an inhibitory drug on the cellular protein kinase activity was evaluated.

Transcriptional and Functional Plasticity Induced by Chronic Insulin Exposure in a Mast Cell-Like Basophilic Leukemia Cell Model

Objective

Secretory granules (SG) and lipid bodies (LB) are the primary organelles that mediate functional responses in mast cells. SG contains histamine and matrix-active proteases, while LB are reservoirs of arachidonic acid and its metabolites, precursors for rapid synthesis of eicosanoids such as LTC₄. Both of these compartments can be dynamically or ontologically regulated, with metabolic and immunological stimuli altering lipid body content and granule numbers responding to contextual signals from tissue. We previously described that chronic in vitro or in vivo hyperinsulinemia expands the LB compartment with a concomitant loss of SG capacity, suggesting that this ratio is dynamically regulated. The objective of the current study is to determine if chronic insulin exposure initiates a transcriptional program that biases model mast cells towards a lipogenic state with accompanying loss of secretory granule biogenesis.

Methods

We used a basophilic leukemic cell line with mucosal mast cell-like features as a model system. We tested the hypothesis that chronic insulin exposure initiates a transcriptional program that biases these model mast cells towards a lipogenic state with accompanying loss of secretory granule biogenesis. Transcriptional arrays were used to map gene expression patterns. Biochemical, immunocytochemical and mediator release assays were used to evaluate organelle numbers and functional responses.

Results

In a mucosal mast cell model, the rat basophilic leukemia line RBL2H3, mast cell granularity and SG numbers are inversely correlated with LB numbers. Chronic insulin exposure appears to modulate gene networks involved in both lipid body biogenesis and secretory granule formation. Western blot analysis confirms upregulation of protein levels for LB proteins, and decreases in proteins that are markers for SG cargo.

Conclusions

The levels of insulin in the extracellular milieu may modify the phenotype of mast cell-like cells in vitro.

20(S)-Protopanaxatriol inhibits release of inflammatory mediators in immunoglobulin E-mediated mast cell activation

Background

Antiallergic effect of 20(S)-protopanaxatriol (PPT), an intestinal metabolite of ginseng saponins, was investigated in guinea pig lung mast cells and mouse bone marrow-derived mast cells activated by a specific antigen/antibody reaction.

Methods

Increasing concentrations of PPT were pretreated 5 min prior to antigen stimulation, and various inflammatory mediator releases and their relevant cellular signaling events were measured in those cells.

Results

PPT dose-dependently reduced the release of histamine and leukotrienes in both types of mast cells. Especially, in activated bone marrow-derived mast cells, PPT inhibited the expression of Syk protein, cytokine mRNA, cyclooxygenase-1/2, and phospholipase A₂ (PLA₂), as well as the activities of various protein kinase C isoforms, mitogen-activated protein kinases, PLA₂, and transcription factors (nuclear factor-κB and activator protein-1).

Conclusion

PPT reduces the release of inflammatory mediators via inhibiting multiple cellular signaling pathways comprising the Ca²⁺ influx, protein kinase C, and PLA₂, which are propagated by Syk activation upon allergic stimulation of mast cells.

Insulin-containing lipogenic stimuli suppress mast cell degranulation potential and up-regulate lipid body biogenesis and eicosanoid secretion in a PPARγ-independent manner

Lipid bodies are most studied in adipocytes, where the lipogenic action of insulin initiates their formation. Here, we test the hypothesis that insulin may regulate lipid body content in mast cells and hence, modify their proinflammatory potential. Our data show that insulin causes lipid body accumulation in RBL2H3 and BMMCs. Lipid body accumulation in mast cells is associated with enhanced levels of leukotriene-synthesizing enzymes (LTC4S and 5-LO). Increased basal and antigen-stimulated release of LTC4 is observed in insulin-treated mast cells. Concomitantly, the insulin-containing lipogenic stimulus induces a phenotypic change in mast cells, where this enhancement in leukotriene levels is accompanied by a marked down-regulation in secretory granule content and release in response to stimulus. Mast cells exposed to insulin exhibit altered scatter and fluorescence properties, accumulating in a SSC(lo)FSC(hi) population that exhibits decreased BS staining and degranulation responses and is enriched in NR-positive lipid bodies and eicosanoid synthesis enzymes. Lipid body accumulation in mast cells is mechanistically distinct from the process in adipocytes; for example, it is independent of PPARγ up-regulation and does not involve significant accumulation of conjugated glycerides. Thus, chronic exposure to metabolic stimuli, such as insulin, may be a determinant of the proinflammatory potential of the mast cell.

Emerging role of mast cells and macrophages in cardiovascular and metabolic diseases

Mast cells are essential in allergic immune responses. Recent discoveries have revealed their direct participation in cardiovascular diseases and metabolic disorders. Although more sophisticated mechanisms are still unknown, data from animal studies suggest that mast cells act similarly to macrophages and other inflammatory cells and contribute to human diseases through cell-cell interactions and the release of proinflammatory cytokines, chemokines, and proteases to induce inflammatory cell recruitment, cell apoptosis, angiogenesis, and matrix protein remodeling. Reduced cardiovascular complications and improved metabolic symptoms in animals receiving over-the-counter antiallergy medications that stabilize mast cells open another era of mast cell biology and bring new hope to human patients suffering from these conditions.

Different roles of mast cells in obesity and diabetes: lessons from experimental animals and humans

Mast cells (MCs) play an important role in allergic hyperresponsiveness and in defending microorganism infections. Recent studies of experimental animals and humans have suggested that MCs participate in obesity and diabetes. MC distribution and activities in adipose tissues may vary, depending on the locations of different adipose tissues. In addition to releasing inflammatory mediators to affect adipose tissue extracellular matrix remodeling and to promote inflammatory cell recruitment and proliferation, MCs directly and indirectly interact and activate adipose tissue cells, including adipocytes and recruited inflammatory cells. Plasma MC protease levels are significantly higher in obese patients than in lean subjects. Experimental obese animals lose body weight after MC inactivation. MC functions in diabetes are even more complicated, and depend on the type of diabetes and on different diabetic complications. Both plasma MC proteases and MC activation essential immunoglobulin E levels are significant risk factors for human pre-diabetes and diabetes mellitus. MC stabilization prevents diet-induced diabetes and improves pre-established diabetes in experimental animals. MC depletion or inactivation can improve diet-induced type 2 diabetes and some forms of type 1 diabetes, but also can worsen other forms of type 1 diabetes, at least in experimental animals. Observations from animal and human studies have suggested beneficial effects of treating diabetic patients with MC stabilizers. Some diabetic patients may benefit from enhancing MC survival and proliferation – hypotheses that merit detailed basic researches and clinical studies.