Chloroquine attenuates thymic stromal lymphopoietin production via suppressing caspase-1 signaling in mast cells

Effect of Chloroquine on Type 2 Inflammatory Response in MC903-Induced Atopic Dermatitis Mice

Introduction

Atopic dermatitis (AD) is a chronic, non-infectious inflammatory dermatosis. Chloroquine (CQ) has long been proven to possess anti-inflammatory properties.

Objective

This paper aims to investigate the impact of CQ on type 2 inflammatory response in MC903-induced AD mice.

Methods

An AD mouse model was established via MC903 induction. After CQ treatment, AD mice were intraperitoneally injected with polyinosinic: polycyclic acid [poly (I:C)] or Nigericin. Dermatitis severity was scored, and the thickness of the left ear was measured. The pathological changes in mouse skin tissues were observed by H&E staining. The number of mast cells was counted via TB staining. The content of peripheral blood T-helper 2 (Th2) cells and levels of immunoglobulin E (IgE), thymic stromal-derived lymphopoietin (TSLP), interleukin (IL)-4, IL-13, interferon (IFN)-γ, IL-1β, and IL-18 were assessed by flow cytometry and ELISA. The levels of toll-like receptor 3 (TLR3), NLRP3, ASC, and cleaved caspase-1 proteins in skin tissues were determined by Western blot.

Results

CQ treatment abated dermatitis severity and left ear thickness in AD mice, alleviated skin damage, reduced mast cell number, diminished IgE, TSLP, IL-4, and IL-13 levels, and peripheral blood Th2 cell content, with no significant changes in IFN-γ level. CQ alleviated type 2 inflammatory response in AD mice by inhibiting the activation of TLR3. CQ suppressed NLRP3 inflammasome activation. Activating TLR3/NLRP3 annulled CQ-mediated alleviation on type 2 inflammatory response in AD mice.

Conclusion

CQ alleviated type 2 inflammatory response in AD mice by inhibiting TLR3 activation and NLRP3 inflammasome activation.

A novel natural Syk inhibitor suppresses IgE-mediated mast cell activation and passive cutaneous anaphylaxis

Spleen tyrosine kinase (Syk) plays a crucial role as a target for allergy treatment due to its involvement in immunoreceptor signaling. The purpose of this study was to identify natural inhibitors of Syk and assess their effects on the IgE-mediated allergic response in mast cells and ICR mice. A list of eight compounds was selected based on pharmacophore and molecular docking, showing potential inhibitory effects through virtual screening. Among these compounds, sophoraflavanone G (SFG) was found to inhibit Syk activity in an enzymatic assay, with an IC50 value of 2.2 μM. To investigate the conformational dynamics of the SYK-SFG system, we performed molecular dynamics simulations. The stability of the binding between SFG and Syk was evaluated using root mean square deviation (RMSD) and root mean square fluctuation (RMSF). In RBL-2H3 cells, SFG demonstrated a dose-dependent suppression of IgE/BSA-induced mast cell degranulation, with no significant cytotoxicity observed at concentrations below 10.0 μM within 24 h. Furthermore, SFG reduced the production of TNF-α and IL-4 in RBL-2H3 cells. Mechanistic investigations revealed that SFG inhibited downstream signaling proteins, including phospholipase Cγ1 (PLCγ1), as well as mitogen-activated protein kinases (AKT, Erk1/2, p38, and JNK), in mast cells in a dose-dependent manner. Passive cutaneous anaphylaxis (PCA) experiments demonstrated that SFG could reduce ear swelling, mast cell degranulation, and the expression of COX-2 and IL-4. Overall, our findings identify naturally occurring SFG as a direct inhibitor of Syk that effectively suppresses mast cell degranulation both in vitro and in vivo.

Comparative analyses of various IgE-mediated and non-IgE-mediated inducers of mast cell degranulation for in vitro study

In vitro investigations of mast cell (MC) degranulation are essential for studying many diseases, particularly allergy and urticaria. Many MC-degranulation inducers are currently available. However, there is no previous systematic comparative analysis of these available inducers in term of their efficacies to induce MC degranulation. Herein, we performed systematic comparisons of efficacies of five well-known and commonly used MC-degranulation inducers. RBL-2H3 cells were sensitized with 50 ng/ml anti-DNP IgE or biotinylated IgE followed by stimulation with 100 ng/ml DNP-BSA or streptavidin, respectively. For non-IgE-mediated inducers, the cells were treated with 5 µg/ml substance P, compound 48/80, or A23187. At 15-, 30-, 45- and 60-min post-induction, several common MC-degranulation markers (including intracellular [Ca2+], β-hexosaminidase release, tryptase expression by immunofluorescence staining, cellular tryptase level by immunoblotting, secretory tryptase level by immunoblotting, CD63 expression by immunofluorescence staining, and CD63 expression by flow cytometry) were evaluated. The data showed that all these markers significantly increased after activation by all inducers. Among them, A23187 provided the greatest degrees of increases in intracellular [Ca2+] and β-hexosaminidase release at all time-points and upregulation of CD63 at one time-point. These data indicate that all these IgE-mediated (anti-DNP IgE/DNP-BSA and biotinylated IgE/streptavidin) and non-IgE-mediated (substance P, compound 48/80, and A23187) inducers effectively induce MC degranulation, while A23187 seems to be the most effective inducer for MC degranulation.

Modulating effect of Eunkyo-san on expression of inflammatory cytokines and angiotensin-converting enzyme 2 in human mast cells

Eunkyo-san is widely used in the treatment of severe respiratory infections. Mast cells not only serve as host cells for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but also they also exacerbate Coronavirus disease in 2019 (COVID-19) by causing a cytokine storm. Here we investigated whether Eunkyo-san and its active compound naringenin regulate the expression of inflammatory cytokines and factors connected to viral infection in activated human mast cell line, HMC-1 cells. Eunkyo-san and naringenin significantly reduced levels of inflammatory cytokines including interleukin (IL)-1β, IL-6, IL-8, thymic stromal lymphopoietin, and tumor necrosis factor-α without impacting cytotoxicity. Eunkyo-san and naringenin reduced levels of factors connected to SARS-CoV-2 infection such as angiotensin-converting enzyme 2 (ACE2, SARS-CoV-2 receptor), transmembrane protease/serine subfamily member 2, and tryptase in activated HMC-1 cells. Treatment with Eunkyo-san and naringenin considerably reduced expression levels of ACE2 transcription factor, AP-1 (C-JUN and C-FOS) by blocking phosphatidylinositide-3-kinase and c-Jun NH2-terminal kinases signaling pathways. In addition, Eunkyo-san and naringenin effectively suppressed activation of signal transducer and activator of transcription 3, nuclear translocation of nuclear factor-κB, and activation of caspase-1 in activated HMC-1 cells. Furthermore, Eunkyo-san and naringenin reduced expression of ACE2 mRNA in two activated mast cell lines, RBL-2H3 and IC-2 cells. The overall study findings showed that Eunkyo-san diminished the expression levels of inflammatory cytokines and ACE2, and these findings imply that Eunkyo-san is able to effectively mitigating the cytokine storm brought on by SARS-CoV-2 infection.

Expression of SARS-CoV-2 receptor angiotensin-converting enzyme 2 by activating protein-1 in human mast cells

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection activates mast cells and induces a cytokine storm, leading to severe Coronavirus disease in 2019 (COVID-19). SARS-CoV-2 employs angiotensin-converting enzyme 2 (ACE2) for cell entry. In the present study, the expression of ACE2 and its mechanism in activated mast cells were studied utilizing the human mast cell line, HMC-1 cells and it was elucidated whether dexamethasone used as a treatment for COVID-19 could regulate ACE2 expression. Here we documented for the first time that levels of ACE2 were increased by stimulation of phorbol 12-myristate 13-acetate and A23187 (PMACI) in HMC-1 cells. Increased levels of ACE2 were significantly diminished by treatment with Wortmannin, SP600125, SB203580, PD98059, or SR11302. The expression of ACE2 was most significantly reduced by the activating protein (AP)-1 inhibitor SR11302. PMACI stimulation enhanced the expression of the transcription factor AP-1 for ACE2. In addition, levels of transmembrane protease/serine subfamily member 2 (TMPRSS2) and tryptase were increased in PMACI-stimulated HMC-1 cells. However, dexamethasone significantly lowered levels of ACE2, TMPRSS2, and tryptase generated by PMACI. Treatment with dexamethasone also reduced activation of signaling molecules linked to ACE2 expression. According to these findings, levels of ACE2 were up-regulated through activation of AP-1 in mast cells, suggesting that suppressing ACE2 levels in mast cells would be a therapeutic approach to lessen the harm caused by COVID-19.

Non-carcinogenic/non-nephrotoxic aristolochic acid IVa exhibited anti-inflammatory activities in mice

Aristolochic acid (AA)-containing herbs have been prescribed for thousands of years as anti-inflammatory drugs, despite the active pharmaceutical ingredients remaining unclear. However, exposure to AAI and AAII has been proven to be a significant risk factor for severe nephropathy and carcinogenicity. AAIVa, an analogue abundant in AA-containing herbs, showed neither carcinogenicity nor nephrotoxicity in our study and other reports, implying that the pharmacological effects of AAIVa on inflammation are worth studying. Herein, we employed RAW 264.7 cells, the ear edema mouse model, and the lipopolysaccharide (LPS)-induced systematic inflammation model in TNF-IRES-Luc mice (tracking TNFα luciferase activities in real-time) to evaluate the anti-inframammary effect of AAIVa. Our results showed that AAIVa could decrease pro-inflammatory cytokines (TNFα and IL-6) production in LPS-stimulated RAW 264.7 cells, indicating its anti-inflammatory effects in vitro. Furthermore, the application of AAIVa (400 and 600 μg/ear) could significantly inhibit phorbol 12-myristate 13-acetate-induced ear edema, suggesting its topical anti-inflammatory activity in vivo. Moreover, LPS-stimulated TNF-IRES-Luc mice were used to investigate the onset and duration of AAIVa on systematic inflammation. A single dosage of AAIVa (100 mg/kg, i.g.) could suppress LPS-triggered inflammation, by decreasing luciferase activities of TNFα at 3 h in TNF-IRES-Luc mice. In addition, the online pharmacological databases predicted that AAIVa might target the regulation of T cell activation-related protein (ADA, ADORA2A, ERBB2) to exhibit anti-inflammatory effect. In conclusion, we demonstrated that AAIVa had anti-inflammatory effect for the first time; our findings are constructive for further studies on pharmacological mechanism of AAIVa.

Hydrogen Sulfide Downregulates Oncostatin M Expression via PI3K/Akt/NF-κB Signaling Processes in Neutrophil-like Differentiated HL-60 Cells

The cytokine oncostatin M (OSM) is regarded as a critical mediator in various inflammatory responses. While the gaseous signaling molecule hydrogen sulfide (H₂S) plays a role in a variety of pathophysiological conditions, such as hypertension, inflammatory pain, osteoarthritis, ischemic stroke, oxidative stress, retinal degeneration, and inflammatory responses, the underlying mechanism of H₂S action on OSM expression in neutrophils needs to be clarified. In this work, we studied how H₂S reduces OSM expression in neutrophil-like differentiated (d)HL-60 cells. To evaluate the effects of H₂S, sodium hydrosulfide (NaHS, a donor that produces H₂S), ELISA, real-time PCR (qPCR), immunoblotting, and immunofluorescence staining were utilized. Although exposure to granulocyte-macrophage colony-stimulating factor (GM-CSF) resulted in upregulated levels of production and mRNA expression of OSM, these upregulated levels were reduced by pretreatment with NaHS in dHL-60 cells. Similarly, the same pretreatment lowered phosphorylated levels of phosphatidylinositol 3-kinase, Akt, and nuclear factor-kB that had been elevated by stimulation with GM-CSF. Overall, our results indicated that H₂S could be a therapeutic agent for inflammatory disorders via suppression of OSM.

The Protective Effect of a Functional Food Consisting of Astragalus membranaceus, Trichosanthes kirilowii, and Angelica gigas or Its Active Component Formononetin against Inflammatory Skin Disorders through Suppression of TSLP via MDM2/HIF1α Signaling Pathways

An herbal mixture (SH003) of Astragalus membranaceus, Trichosanthes kirilowii, and Angelica gigas exhibits therapeutic effects on carcinomas and immunosuppression. However, the role of JRP-SNF102, which is an advanced mixture of SH003, in regulating inflammatory responses is unexplored. We aim to substantiate the therapeutic potential of JRP-SNF102 and its active component, formononetin (FMN), as a functional food that moderates inflammatory responses. The inhibitory effects of JRP-SNF102 or FMN on thymic stromal lymphopoietin (TSLP) levels were evaluated in phorbol 12-myristate 13-acetate (PMA) plus A23187-activated human mast cell line-1 (HMC-1) cells and a mouse model of PMA-induced ear edema. The JRP-SNF102 or FMN inhibited the secretion and mRNA expression of TSLP and vascular endothelial growth factor (VEGF) in the activated HMC-1 cells. The expression levels of murine double minute 2 (MDM2), hypoxia-inducible factor 1α (HIF1α), and NF-κB were also suppressed by JRP-SNF102 or FMN in the activated HMC-1 cells. The JRP-SNF102 or FMN inhibited TSLP and VEGF levels, attenuating redness and ear thickness in mice with acute ear edema; JRP-SNF102 or FMN reduced the expression levels of MDM2, HIF1α, and NF-κB in the ear tissues. These findings suggest the potential for JRP-SNF102 as a functional food in the treatment of inflammatory skin disorders through suppression of TSLP and VEGF.

The immune-enhancing effects of a mixture of Astragalus membranaceus (Fisch.) Bunge, Angelica gigas Nakai, and Trichosanthes Kirilowii (Maxim.) or its active constituent nodakenin

ETHNOPHARMACOLOGICAL RELEVANCE

A mixture (SH003) of Astragalus membranaceus (Fisch.) Bunge, Angelica gigas Nakai, and Trichosanthes Kirilowii (Maxim.) has beneficial effects against several carcinomas. There have been few reports on an immune-enhancing activity of SH003 and its active constituent nodakenin.

AIM OF THE STUDY

This study aimed at identifying the immune-enhancing effect of SH003 and nodakenin.

MATERIALS AND METHODS

The immune-enhancing effect was evaluated using RAW264.7 macrophages, mouse primary splenocytes, and a cyclophosphamide (CP)-induced immunosuppression murine model.

RESULTS

The results show that SH003 or nodakenin stimulated the production levels of granulocyte colony-stimulating factor, IL-12, IL-2, IL-6, TNF-α, and nitric oxide (NO) and the expression levels of iNOS in RAW264.7 macrophages. SH003 or nodakenin also enhanced NF-κB p65 activation in RAW264.7 macrophages. SH003 or nodakenin stimulated the production levels of IFN-γ, IL-12, IL-2, TNF-α, and NO and the expression levels of iNOS in splenocytes. SH003 or nodakenin increased the splenic lymphocyte proliferation and splenic NK cell activity. In addition, SH003 or nodakenin increased the levels of IFN-γ, IL-12, IL-2, IL-6, and TNF-α in the serum and spleen of CP-treated mice, alleviating CP-induced immunosuppression.

CONCLUSION

Taken together, the results of this study show that SH003 improved immunosuppression through the activation of macrophages, splenocytes, and NK cells. These findings suggest that SH003 could be applied as a potential immunostimulatory agent for a variety of diseases caused or exacerbated by immunodeficiency.

Resveratrol Downregulates Granulocyte-Macrophage Colony-Stimulating Factor-Induced Oncostatin M Production through Blocking of PI3K/Akt/NF-κB Signal Cascade in Neutrophil-like Differentiated HL-60 Cells

Oncostatin M (OSM) is essential in a wide range of inflammatory responses, and most OSM is produced by neutrophils in respiratory diseases. While resveratrol (RES) is regarded as an anti-inflammatory agent in a variety of conditions, the mechanism of OSM inhibition by RES in neutrophils remains to be elucidated. In this study, we investigated whether RES could inhibit OSM production in neutrophil-like differentiated (d)HL-60 cells. The effects of RES were measured by means of an enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blotting. Increases in production and mRNA expression of OSM resulted from the addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) in neutrophil-like dHL-60 cells; however, these increases were downregulated by RES treatment. Exposure to GM-CSF led to elevations of phosphorylation of phosphatidylinositol 3-kinase (PI3K), Akt, and nuclear factor (NF)-kB. Treatment with RES induced downregulation of the phosphorylated levels of PI3K, Akt, and NF-κB in neutrophil-like dHL-60 cells. These results suggest that RES could be applicable to prevent and/or treat inflammatory disorders through blockade of OSM.

SBT (Composed of Panax ginseng and Aconitum carmichaeli) and Stigmasterol Enhances Nitric Oxide Production and Exerts Curative Properties as a Potential Anti-Oxidant and Immunity-Enhancing Agent

Immune dysregulation is a risk factor for several diseases, including infectious diseases. Immunostimulatory agents have been used for the treatment of immune dysregulation, but deleterious adverse effects have been reported. The present study aims to establish the anti-oxidant and immunity-enhancing effects of Sambu-Tang (SBT), composed of Panax ginseng and Aconitum carmichaeli, and stigmasterol (Stig), an active compound of SBT. Immune-related factors were analyzed in RAW264.7 macrophage cells, mouse primary splenocytes, and the serum and spleen of cyclophosphamide-induced immunosuppressed mice. Results showed that the production levels of nitric oxide (NO) and expression levels of inducible NO synthase and heme oxygenase-1 were increased following SBT or Stig treatment in RAW264.7 cells. SBT or Stig increased the production levels of G-CSF, IFN-γ, IL-12, IL-2, IL-6, and TNF-α and induced the activation of NF-κB in RAW264.7 cells. SBT or Stig promoted splenic lymphocyte proliferation and increased splenic NK cell cytotoxic activity. In addition, SBT or Stig enhanced the levels of IFN-γ, IL-12, IL-2, IL-6, or TNF-α in the serum and spleen of the immunosuppressed mice. SBT or Stig increased the superoxide dismutase activity in the spleen. Collectively, SBT and Stig possess anti-oxidant and immunomodulatory activities, so they may be considered effective natural compounds for the treatment of various symptoms caused by immune dysregulation.