Nitric oxide: a major determinant of mast cell phenotype and function

Osthole ameliorates chronic pruritus in 2,4-dichloronitrobenzene-induced atopic dermatitis by inhibiting IL-31 production

Objective

This study aims to elucidate the therapeutic potential of osthole for the treatment of atopic dermatitis (AD), focusing on its ability to alleviate chronic pruritus (CP) and the underlying molecular mechanisms.

Methods

In this study, we investigated the anti-inflammatory effects of osthole in both a 2,4-dichloronitrobenzene (DNCB)-induced AD mouse model and tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) stimulated huma immortalized epidermal (HaCaT) cells. The anti-itch effect of osthole was specifically assessed in the AD mouse model. Using methods such as hematoxylin and eosin (HE) staining, enzyme-linked immunosorbent assay (ELISA), western blot (WB), quantitative real-time PCR (qRT-PCR), and immunofluorescence staining.

Results

Osthole improved skin damage and clinical dermatitis scores, reduced scratching bouts, and decreased epidermal thickness AD-like mice. It also reduced the levels of interleukin (IL)-31 and IL-31 receptor A (IL-31 RA) in both skin tissues and HaCaT cells. Furthermore, Osthole suppressed the protein expression levels of phosphor-p65 (p-p65) and phosphor-inhibitor of nuclear factor kappa-Bα (p-IκBα). Meanwhile, it increased the protein expression levels of peroxisome proliferator-activated receptor α (PPARα) and PPARγ in HaCaT cells.

Conclusion

These findings indicated that osthole effectively inhibited CP in AD by activating PPARα, PPARγ, repressing the NF-κB signaling pathway, as well as the expression of IL-31 and IL-31 RA.

Abnormal cGMP-dependent protein kinase I-mediated decidualization in preeclampsia

Defective decidual function contributes to the pathogenesis of preeclampsia. However, the precise mechanism of defective decidua during preeclampsia has not been characterized. During decidualization, endometrial stromal cells undergo phenotypic changes that are consistent with mesenchymal-epithelial transition (MET). cGMP-dependent kinase protein I (PKGI)/VASP signaling is important in cell motility proliferation, differentiation and cell adhesion. To investigate this aim, we analyzed PKGI levels, phosphorylated VASP protein levels, and eNOS and sGC protein expression levels during pregnancy complicated by preeclampsia, which indicated that PKGI/VASP signaling function is decreased by the condition. Moreover, we evaluated the differential expression of genes that regulate MET in the decidua resulting from preeclampsia and healthy pregnancies. We discovered that vimentin mRNA levels are decreased in the decidua of preeclampsia, which indicates that excessive MET occurs in the decidua of preeclampsia pregnancies. A fundamental developmental MET program occurred in response to signaling pathways. These results suggest the important role of decreased PKGI/VASP signaling during excessive MET in the pathogenesis of preeclampsia.

Cross talk between polysulfide and nitric oxide in rat peritoneal mast cells

The aim of this study was to define the effects of polysulfide on intracellular Ca(2+) concentration ([Ca(2+)]i) and the underlying machinery, especially from the hydrogen sulfide (H2S) and nitric oxide (NO) perspectives, in rat peritoneal mast cells. We found that a polysulfide donor, Na2S4, increased [Ca(2+)]i, which is both extracellular and intracellular Ca(2+) dependent. Intracellular Ca(2+) release induced by Na2S4 was attenuated by the addition of a ryanodine receptor blocker. A slow-releasing H2S donor, GYY4137, dose dependently increased [Ca(2+)]i that was independent from extracellular Ca(2+) influx. The GYY4137-induced [Ca(2+)]i release was partially attenuated in the presence of the ryanodine receptor blocker. Both polysulfide and H2S donors increased the intracellular NO levels in DAF-2-loaded mast cells, which were abolished by an NO scavenger, cPTIO. Inhibition of NO synthase (NOS) significantly abolished the polysulfide- or H2S-donor-induced [Ca(2+)]i elevation in the absence of extracellular Ca(2+) An NO donor, diethylamine (DEA) NONOate, increased [Ca(2+)]i in a concentration-dependent manner, in which both extracellular and intracellular Ca(2+) are associated. At higher concentrations, the DEA NONOate-induced [Ca(2+)]i increases were attenuated in the absence of extracellular Ca(2+) and by the addition of the ryanodine receptor blocker. H2S and NO dose dependently induced polysulfide production. Curiously, polysulfide, H2S, and NO donors had no effect on mast cell degranulation. Among synthases, cystathionine-γ-lyase, and neuronal NOS seemed to be the major H2S- and NO-producing synthases, respectively. These results indicate that polysulfide acts as a potential signaling molecule that regulates [Ca(2+)]i homeostasis in rat peritoneal mast cells via a cross talk with NO and H2S.

Human mast cell activation with viruses and pathogen products

Mast cells have been demonstrated to have critical roles in host defense against a number of types of pathogens. In order to better understand how mast cells participate in effective immune responses, it is important to evaluate their ability to respond directly to pathogens and their products. In the current chapter we provide a methodology to evaluate human mast cell responses to a number of bacterial and fungal pathogen products and to mammalian reovirus as a model of acute viral infection. These methods should provide key information necessary to aid in the effective design of experiments to evaluate human mast cell responses to a number of other organisms. However, it is important to carefully consider the biology of the mast cell subsets and pathogens involved and the optimal experimental conditions necessary to evaluate mediators of interest.

Evaluation of the immunity activity of glycyrrhizin in AR mice

In this study, we evaluated effect of glycyrrhizin on immunity function in allergic rhinitis (AR) mice. The AR mice model were induced by dripping ovalbumin in physiological saline (2 mg mL⁻¹, 10 μL) into the bilateral nasal cavities using a micropipette. After the AR model was induced, mice were randomly divided into six groups: the normal control, model, lycopene 20 mg kg⁻¹ (as positive control drug) group, and glycyrrhizin 10, 20, 30 mg kg⁻¹ groups. After the sensitization day 14, lycopene (20 mg/kg BW) and glycyrrhizin (10, 20 and 30 mg/kg BW) were given orally for 20 days once a day. Mice in the normal control and model groups were given saline orally once a day for 20 days. Results showed that glycyrrhizin treatment could dose-dependently significantly reduce blood immunoglobulin E (IgE), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6), nitrous oxide (NO), tumor necrosis factor-alpha (TNF-α) levels and nitrous oxide synthase (NOS) activity and enhance blood immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM), interleukin-2 (IL-2) and interleukin-12 (IL-12) levels in AR mice. Furthermore, glycyrrhizin treatment could dose-dependently significantly enhance acetylcholinesterase (AchE) activity and reduce substance P (SP) level in peripheral blood and nasal mucosa of AR mice. We conclude that glycyrrhizin can improve immunity function in AR mice, suggesting a potential drug for the prevention and therapy of AR.

Antianaphylactic and mast cell stabilization activity of Strychnos potatorum Linn. seed

AIM

The antianaphylactic activity of Strychnos potatorum Linn seed extract was evaluated by using compound 48/80 induced anaphylaxis and mast cell stabilization was studied by using peritoneal mast cells of rats. The possible antianaphylactic and mast cell stabilization mechanism was evaluated by using compound 48/80 induced mast cell activation and level of nitric oxide in rat peritoneal mast cells.

MATERIALS AND METHODS

Anaphylactic shock in mice was induced by the intraperitoneal administration of 8 mg/kg compound 48/80, prior to induction of anaphylaxis the animals were treated with S. potatorum Linn. seed extract administered orally 1 h before administration of compound 48/80, the rate mortality was observed in each group of animals. Mast cell stabilization was seen by preincubation of mast cells with the compound 48/80 and the extracts.

RESULTS

This study indicates that the chloroform, petroleum ether, and methanolic extracts were shown potent and has significant (P < 0.01 and P < 0.001) inhibitory effects on compound 48/80 induced anaphylactic reaction and mast cell activation. This compound also inhibited significantly compound 48/80 induced increased level of nitric oxide in rat peritoneal mast cells.

CONCLUSION

We conclude from this study that the different extracts of S. potatorum seed have potent antianaphylactic activity through mast cell stabilization and inhibition of nitric oxide synthesis. The inhibitory effect of S. potatorum Linn. on release of histamine and nitric oxide protects from compound 48/80 induced anaphylactic reaction may be through blocking vasodilatation, decrease vascular resistance, hypotension and tachycardia induced by immunogenic agent used in this study.

Protein tyrosine nitration of aldolase in mast cells: a plausible pathway in nitric oxide-mediated regulation of mast cell function

NO is a short-lived free radical that plays a critical role in the regulation of cellular signaling. Mast cell (MC)-derived NO and exogenous NO regulate MC activities, including the inhibition of MC degranulation. At a molecular level, NO acts to modify protein structure and function through several mechanisms, including protein tyrosine nitration. To begin to elucidate the molecular mechanisms underlying the effects of NO in MCs, we investigated protein tyrosine nitration in human MC lines HMC-1 and LAD2 treated with the NO donor S-nitrosoglutathione. Using two-dimensional gel Western blot analysis with an anti-nitrotyrosine Ab, together with mass spectrometry, we identified aldolase A, an enzyme of the glycolytic pathway, as a target for tyrosine nitration in MCs. The nitration of aldolase A was associated with a reduction in the maximum velocity of aldolase in HMC-1 and LAD2. Nuclear magnetic resonance analysis showed that despite these changes in the activity of a critical enzyme in glycolysis, there was no significant change in total cellular ATP content, although the AMP/ATP ratio was altered. Elevated levels of lactate and pyruvate suggested that S-nitrosoglutathione treatment enhanced glycolysis. Reduced aldolase activity was associated with increased intracellular levels of its substrate, fructose 1,6-bisphosphate. Interestingly, fructose 1,6-bisphosphate inhibited IgE-mediated MC degranulation in LAD2 cells. Thus, for the first time we report evidence of protein tyrosine nitration in human MC lines and identify aldolase A as a prominent target. This posttranslational nitration of aldolase A may be an important pathway that regulates MC phenotype and function.

Physiological effects of NO-cGMP pathway on ovarian steroidogenesis in rat

The present study was undertaken to determine whether NO involved in the regulation of ovarian steroidogenesis in female rats. The purpose of the present study was to investigate whether NO might inhibits ovarian steroidogenesis. Female rats were divided of five rats including, receiving, N-omega-nitro-L-arginine methyle ester (L-NAME), an inhibitor of NO synthesis, Trinitroglycerin (TNG), an NO donor, L-arginine, normal saline. After 21 days, concenteration of progesterone and oesteradiol were measured by Electerochemiluminescence (ECL). Result showed that: TNG significantly decreased concentration of progesterone (50%) and L-NAME partially increased ovarian oesteradiol, but not differ effect from that rats treated with trinitroglycerin.

Regulation and function of the protein inhibitor of nitric oxide synthase (PIN)/dynein light chain 8 (LC8) in a human mast cell line

The protein inhibitor of nitric oxide synthase (PIN) was independently identified as an inhibitor of nitric oxide (NO) produced by neuronal nitric oxide synthase (nNOS), and as a member of the cellular dynein light chain family, dynein light chain 8 (LC8), responsible for intracellular protein trafficking. Mast cells (MC) are involved in several homeostatic and pathological processes and can be regulated by NO. This study describes the expression of PIN/LC8 in the human MC line HMC-1. We also studied if PIN/LC8 binds nNOS, and what role this might have in leukotriene (LT) production. We found that PIN/LC8 mRNA and protein was expressed in HMC-1. Using a GST-PIN construct, we showed PIN binds to nNOS, but not endothelial (e)NOS in HMC-1; in our studies HMC-1 did not express inducible (i)NOS. Intracellular delivery of anti-PIN/LC8 antibody enhanced ionophore (A23187)-induced LT production through an unknown mechanism. Thus we established for the first time expression of PIN/LC8 in human MC, its ability to bind nNOS, and the effect that blocking it has on LT production in a human MC lines.

Role of nitric oxide in mast cells: controversies, current knowledge, and future applications

Mast cells (MC) are important effector cells in allergic disorders. Recently, the role of MC in innate and adaptive immunity is gaining prominence. Nitric oxide is an important signaling molecule and its production in mast cell has been reported widely. However, controversy exists about whether MC produce NO. This review addresses the role of NO in MC biology and the reasons behind the controversy and discusses effects of NO in regulation of MC phenotype and function.