Sauchinone suppresses FcεRI-mediated mast cell signaling and anaphylaxis through regulation of LKB1/AMPK axis and SHP-1-Syk signaling module

Eucommia lignans alleviate the progression of diabetic nephropathy through mediating the AR/Nrf2/HO-1/AMPK axis in vivo and in vitro

Lignans derived from Eucommia ulmoides Oliver (Eucommia lignans) inhibit the progression of inflammatory diseases, while their effect on the progression of diabetic nephropathy (DN) remained unclear. This work was designed to assess the function of Eucommia lignans in DN. The major constituents of Eucommia lignans were analyzed by UPLC-Q-TOF-MS/MS. The binding between Eucommia lignans and aldose reductase (AR) was predicted by molecular docking. Eucommia lignans (200, 100, and 50 mg·kg^-1) were used in model animals to evaluate their renal function changes. Rat glomerular mesangial cells (HBZY-1) were transfected with sh-AR, sh-AMPK, and oe-AR in the presence of high glucose (HG) or HG combined with Eucommia lignans to evaluate whether Eucommia lignans affected HG-induced cell injury and mitochondrial dysfunction through the AR/Nrf2/HO-1/AMPK axis. Eucommia lignans significantly attenuated the progression of DN in vivo. Eucommia lignans notably reversed HG-induced upregulation of inflammatory cytokines and mitochondrial injury, while downregulating the levels of Cyto c, caspase 9, AR, and NOX4 in HBZY-1 cells. In contrast, HG-induced downregulation of Nrf2, HO-1 and p-AMPKα levels were abolished by Eucommia lignans. Meanwhile, knockdown of AR exerted similar therapeutic effect of Eucommia lignans on DN progression, and AR overexpression reversed the effect of Eucommia lignans. Eucommia lignans alleviated renal injury through the AR/Nrf2/HO-1/AMPK axis. Thus, these findings might provide evidence for the use of Eucommia lignans in treating DN.

Thalidomide Attenuates Mast Cell Activation by Upregulating SHP-1 Signaling and Interfering with the Action of CRBN

Allergy is a chronic inflammatory disease, and its incidence has increased worldwide in recent years. Thalidomide, which was initially used as an anti-emetic drug but was withdrawn due to its teratogenic effects, is now used to treat blood cancers. Although the anti-inflammatory and immunomodulatory properties of thalidomide have been reported, little is known about its influence on the mast cell-mediated allergic reaction. In the present study, we aimed to evaluate the anti-allergic activity of thalidomide and the underlying mechanism using mouse bone marrow-derived mast cells (BMMCs) and passive cutaneous anaphylaxis (PCA) mouse models. Thalidomide markedly decreased the degranulation and release of lipid mediators and cytokines in IgE/Ag-stimulated BMMCs, with concurrent inhibition of FcεRI-mediated positive signaling pathways including Syk and activation of negative signaling pathways including AMP-activated protein kinase (AMPK) and SH2 tyrosine phosphatase-1 (SHP-1). The knockdown of AMPK or SHP-1 with specific siRNA diminished the inhibitory effects of thalidomide on BMMC activation. By contrast, the knockdown of cereblon (CRBN), which is the primary target protein of thalidomide, augmented the effects of thalidomide. Thalidomide reduced the interactions of CRBN with Syk and AMPK promoted by FcεRI crosslinking, thereby relieving the suppression of AMPK signaling and suppressing Syk signaling. Furthermore, oral thalidomide treatment suppressed the PCA reaction in mice. In conclusion, thalidomide suppresses FcεRI-mediated mast cell activation by activating the AMPK and SHP-1 pathways and antagonizing the action of CRBN, indicating that it is a potential anti-allergic agent.

Antagonism of m3 Alleviates Type 2 Inflammation in Allergic Rhinitis Mice

Background

Type 2 immune cells play a pivotal role in allergic rhinitis (AR). Increasing evidence shows that inhibition of cholinergic nerve activity decreases the severity of airway diseases including asthma and AR. However, the role of the cholinergic receptor muscarinic 3 (m3) in type 2 inflammation in AR is unknown.

Objective

We aimed to investigate the effect of m3 on the type 2 immune response, including both T helper 2 (Th2)-mediated and type 2 innate lymphocyte (ILC2)-mediated inflammation, in AR.

Methods

Peripheral blood mononuclear cells (PBMCs) from human were cultured in vitro. Treatment with the m3 antagonist 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP) was used. The percentages of Th2 and ILC2 cells in PBMCs were evaluated by flow cytometry. AR mouse models were established by house dust mite (HDM) sensitization, and treated with tiotropium intranasally. The expression of Th2 cytokines, ILC2 cytokines and related factors in the nasal mucosa was assessed by immunohistochemistry and quantitative real-time polymerase chain reaction. Serum HDM-specific immunoglobulin E (sIgE) level was detected by enzyme-linked immunosorbent assay.

Results

Both Th2 and ILC2 percentages in PBMCs were decreased after 4-DAMP treatment. Similarly, the levels of Th2 cytokines (interleukin 4 [IL-4] and IL-13) and ILC2 cytokines and related factors (IL-25, IL-33, GATA3 and RORα) were significantly decreased in the nasal mucosa of AR mice after tiotropium treatment. Furthermore, tiotropium treatment decreased the nasal symptom score, the serum sIgE level and eosinophil infiltration in AR mice. In addition, tiotropium decreased phospholipase Cγ1 (PLCγ1), PLCγ2, nuclear factor of activated T cell 1 (NFATc1), and NFATc2 mRNA levels in AR mice.

Conclusion

Antagonism of m3 alleviated type 2 inflammation in the nasal mucosa of AR mice.

Targeting Sirt1, AMPK, Nrf2, CK2, and Soluble Guanylate Cyclase with Nutraceuticals: A Practical Strategy for Preserving Bone Mass

There is a vast pre-clinical literature suggesting that certain nutraceuticals have the potential to aid the preservation of bone mass in the context of estrogen withdrawal, glucocorticoid treatment, chronic inflammation, or aging. In an effort to bring some logical clarity to these findings, the signaling pathways regulating osteoblast, osteocyte, and osteoclast induction, activity, and survival are briefly reviewed in the present study. The focus is placed on the following factors: the mechanisms that induce and activate the RUNX2 transcription factor, a key driver of osteoblast differentiation and function; the promotion of autophagy and prevention of apoptosis in osteoblasts/osteoclasts; and the induction and activation of NFATc1, which promotes the expression of many proteins required for osteoclast-mediated osteolysis. This analysis suggests that the activation of sirtuin 1 (Sirt1), AMP-activated protein kinase (AMPK), the Nrf2 transcription factor, and soluble guanylate cyclase (sGC) can be expected to aid the maintenance of bone mass, whereas the inhibition of the serine kinase CK2 should also be protective in this regard. Fortuitously, nutraceuticals are available to address each of these targets. Sirt1 activation can be promoted with ferulic acid, N1-methylnicotinamide, melatonin, nicotinamide riboside, glucosamine, and thymoquinone. Berberine, such as the drug metformin, is a clinically useful activator of AMPK. Many agents, including lipoic acid, melatonin, thymoquinone, astaxanthin, and crucifera-derived sulforaphane, can promote Nrf2 activity. Pharmacological doses of biotin can directly stimulate sGC. Additionally, certain flavonols, notably quercetin, can inhibit CK2 in high nanomolar concentrations that may be clinically relevant. Many, though not all, of these agents have shown favorable effects on bone density and structure in rodent models of bone loss. Complex nutraceutical regimens providing a selection of these nutraceuticals in clinically meaningful doses may have an important potential for preserving bone health. Concurrent supplementation with taurine, N-acetylcysteine, vitamins D and K2, and minerals, including magnesium, zinc, and manganese, plus a diet naturally high in potassium, may also be helpful in this regard.

Nutraceutical Aid for Allergies - Strategies for Down-Regulating Mast Cell Degranulation

Interactions of antigens with the mast cell FcεRI-IgE receptor complex induce degranulation and boost synthesis of pro-inflammatory lipid mediators and cytokines. Activation of spleen tyrosine kinase (Syk) functions as a central hub in this signaling. The tyrosine phosphatase SHP-1 opposes Syk activity; stimulation of NADPH oxidase by FcεRI activation results in the production of oxidants that reversibly inhibit SHP-1, up-regulating the signal from Syk. Activated AMPK can suppress Syk activation by the FcεRI receptor, possibly reflecting its ability to phosphorylate the FcεRI beta subunit. Cyclic GMP, via protein kinase G II, enhances the activity of SHP-1 by phosphorylating its C-terminal region; this may explain its inhibitory impact on mast cell activation. Hydrogen sulfide (H₂S) likewise opposes mast cell activation; H₂S can boost AMPK activity, up-regulate cGMP production, and trigger Nrf2-mediated induction of Phase 2 enzymes - including heme oxygenase-1, whose generation of bilirubin suppresses NADPH oxidase activity. Phycocyanobilin (PCB), a chemical relative of bilirubin, shares its inhibitory impact on NADPH oxidase, rationalizing reported anti-allergic effects of PCB-rich spirulina ingestion. Phase 2 inducer nutraceuticals can likewise oppose the up-regulatory impact of NADPH oxidase on FcεRI signaling. AMPK can be activated with the nutraceutical berberine. High-dose biotin can boost cGMP levels in mast cells via direct stimulation of soluble guanylate cyclase. Endogenous generation of H₂S in mast cells can be promoted by administering N-acetylcysteine and likely by taurine, which increases the expression of H₂S-producing enzymes in the vascular system. Mast cell stabilization by benifuuki green tea catechins may reflect the decreased surface expression of FcεRI.

Perfluorooctane sulfonate and bisphenol A induce a similar level of mast cell activation via a common signaling pathway, Fyn-Lyn-Syk activation

Perfluoroalkyl compounds (PFCs) as food contaminants are widely distributed persistent organic pollutants (POPs) and have been suggested to induce immune dysfunction. However, their effects on immune function are not conclusive. Mast cells play a central role in allergic and non-allergic inflammatory responses. Therefore, we have examined the effects of PFCs (PFHxS, PFOA, PFOS) on mast cell-mediated inflammatory responses using in vitro mouse bone marrow-derived mast cells (BMMCs) and human mast cells (HMC-1) and in vivo mice model. The effects of PFCs were compared with those of bisphenol A (BPA), a well-studied environmental pollutant. Among PFCs tested, PFOS had the highest effects. Both PFOS and BPA increased degranulation and production of inflammatory eicosanoids in mast cells at a similar level, which subsequently led to increased skin edema and serum LTC₄ and PGD₂ in mice. Both PFOS and BPA increased not only downstream signaling (PLCγ1, AKT, ERK), but also upstream signaling (Fyn, Lyn, Syk/LAT) in mast cells. Taken together, PFOS and BPA induce mast cell-mediated inflammatory responses via a common signaling pathways. Our results may help establish the scientific basis for understanding the etiology of mast cell-mediated inflammatory responses and improve the immune dysfunction risk assessment for emerging POPs such as PFCs.

Bruton's tyrosine kinase inhibition effectively protects against human IgE-mediated anaphylaxis

No known therapies can prevent anaphylaxis. Bruton's tyrosine kinase (BTK) is an enzyme thought to be essential for high-affinity IgE receptor (FcεRI) signaling in human cells. We tested the hypothesis that FDA-approved BTK inhibitors (BTKis) would prevent IgE-mediated responses including anaphylaxis. We showed that irreversible BTKis broadly prevented IgE-mediated degranulation and cytokine production in primary human mast cells and blocked allergen-induced contraction of isolated human bronchi. To address their efficacy in vivo, we created and used what we believe to be a novel humanized mouse model of anaphylaxis that does not require marrow ablation or human tissue implantation. After a single intravenous injection of human CD34+ cells, NSG-SGM3 mice supported the population of mature human tissue-resident mast cells and basophils. These mice showed excellent responses during passive systemic anaphylaxis using human IgE to selectively evoke human mast cell and basophil activation, and response severity was controllable by alteration of the amount of allergen used for challenge. Remarkably, pretreatment with just 2 oral doses of the BTKi acalabrutinib completely prevented moderate IgE-mediated anaphylaxis in these mice and also significantly protected against death during severe anaphylaxis. Our data suggest that BTKis may be able to prevent anaphylaxis in humans by inhibiting FcεRI-mediated signaling.

Targeting the FcεRI Pathway as a Potential Strategy to Prevent Food-Induced Anaphylaxis

Despite attempts to halt it, the prevalence of food allergy is increasing, and there is an unmet need for strategies to prevent morbidity and mortality from food-induced allergic reactions. There are no known medications that can prevent anaphylaxis, but several novel therapies show promise for the prevention of food-induced anaphylaxis through targeting of the high-affinity IgE receptor (FcϵRI) pathway. This pathway includes multiple candidate targets, including tyrosine kinases and the receptor itself. Small molecule inhibitors of essential kinases have rapid onset of action and transient efficacy, which may be beneficial for short-term use for immunotherapy buildup or desensitizations. Short courses of FDA-approved inhibitors of Bruton’s tyrosine kinase can eliminate IgE-mediated basophil activation and reduce food skin test size in allergic adults, and prevent IgE-mediated anaphylaxis in humanized mice. In contrast, biologics may provide longer-lasting protection, albeit with slower onset. Omalizumab is an anti-IgE antibody that sequesters IgE, thereby reducing FcϵRI expression on mast cells and basophils. As a monotherapy, it can increase the clinical threshold dose of food allergen, and when used as an adjunct for food immunotherapy, it decreases severe reactions during buildup phase. Finally, lirentelimab, an anti-Siglec-8 antibody currently in clinical trials, can prevent IgE-mediated anaphylaxis in mice through mast cell inhibition. This review discusses these and other emerging therapies as potential strategies for preventing food-induced anaphylaxis. In contrast to other food allergy treatments which largely focus on individual allergens, blockade of the FcϵRI pathway has the advantage of preventing clinical reactivity from any food.

Pterostilbene Inhibits FcεRI Signaling through Activation of the LKB1/AMPK Pathway in Allergic Response

In this study, the role and mechanism of pterostilbene (Pts) in mast cell degranulation in vitro and in vivo were investigated. The results showed that Pts inhibited mast cell-mediated local passive allergic reactions in mice. In addition, treatment with Pts reduced both histamine release and calcium influx in rat peritoneal mast cells and RBL-2H3 cells and reduced IgE-mediated mast cell activation. Furthermore, the mechanism underlying Pts inhibition of mast cell signaling was probed via studying the effects of Pts on liver kinase B1 (LKB1), including the use of the LKB1 activator metformin and siRNA knockdown of LKB1. The data showed that Pts reduced the release of inflammatory mediators such as tumor necrosis factor-α, interleukin-6, leukotriene C4, and prostaglandin D2 in mast cells by activating the LKB1/adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway. Furthermore, Pts inhibited phosphorylation of FcεRI and FcεRI-mediated degranulation in RBL-2H3 cells. These effects were attenuated after LKB1 knockdown. Taken together, Pts could inhibit FcεRI signaling through activation of the LKB1/AMPK signaling pathway in IgE-mediated mast cell activation. Thus, Pts might be an effective therapeutic agent for mast cell-mediated allergic diseases.

Sauchinone ameliorates intestinal inflammation and promotes Th17 cell production of IL-10 via Blimp-1

Inflammatory bowel disease (IBD) is characterized by chronic, unpredictable relapsing and inflammatory disease of the gastrointestinal tract. Daily diet patterns have long been one of the most important hotspots for IBD therapeutic strategies. Sauchinone (SAU), a key bioactive lignin isolated from the roots of the herb Saururus chinensis, has been known to play an anti-inflammatory role in several diseases. However, its effect on IBD has not yet been investigated. In the current study, we established 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice and treated them with SAU. Flow cytometric analysis was performed to determine the phenotype of T cells in the lamina propria. qRT-PCR and ELISA were performed to measure cytokine transcript and protein levels, respectively. We found that SAU ameliorated TNBS-induced mouse colitis and inflammatory responses in mucosal tissues and peripheral blood CD4⁺ T cells from IBD patients. SAU significantly suppressed Th17 differentiation but facilitated IL-10 production, and SAU-treated Th17 cells exhibited inhibitory functions in vitro and in vivo. Mechanistically, we demonstrated that SAU induced Blimp-1 expression (encoded by Prdm1) in Th17 cells, and SAU failed to increase IL-10 production in Prdm1-knockout Th17 cells. Our data reveal an uncharacterized mechanism through which SAU regulates intestinal inflammation and Th17 differentiation.