Effects of antihistamine on up-regulation of histamine H1 receptor mRNA in the nasal mucosa of patients with pollinosis induced by controlled cedar pollen challenge in an environmental exposure unit

Structure-activity relationship studies of pyrogallol as a calcineurin/NFAT signaling suppressor

Previously, we have shown that pyrogallol alleviated nasal symptoms and suppressed IL-9 gene up-regulation in allergy model rats by inhibiting calcineurin/NFAT signaling. As pyrogallol has antioxidative activity, it may be responsible for inhibiting calcineurin/NFAT signaling-mediated IL-9 gene expression. However, the relationship between antioxidative activity and suppression of IL-9 gene expression has not been elucidated yet. Here, we conducted the structure-activity relationship studies of pyrogallol and its structurally related compounds to understand the mechanism of IL-9 gene suppression by pyrogallol. 2, 2-Diphenyl-1-picrylhydrazyl radical scavenging assay showed that the antioxidative activity of catechol, resorcinol, phloroglucinol, and gallic acid is 60.1%, 10.4%, 18.8%, and 113.5% of pyrogallol, respectively. Catechol, resorcinol, and phloroglucinol did not suppress NFAT dephosphorylation. Gallic acid suppressed dephosphorylation of NFAT. Gallic acid also suppressed ionomycin-induced up-regulation of IL-9 gene expression with the IC50 value of 82.6 μM. However, catechol, resorcinol and phloroglucinol showed no suppressive activity. In addition, using gallic acid-immobilized beads, we isolated and identified Poly(U)-binding-splicing factor 60 (PUF60) as a pyrogallol binding protein. These results suggest that the antioxidative activity of pyrogallol is not likely to be the mechanism of IL-9 gene suppression. Data also suggest that PUF60 is one of its target molecules responsible for the suppression of calcineurin/NFAT signaling by pyrogallol.

Establishment of a human nasal epithelium model of histamine-induced inflammation to assess the activity of fexofenadine as an inverse agonist and its link to clinical benefit

Background

Fexofenadine (FEX) is an antihistamine that acts as an inverse agonist against histamine (HIS) receptor 1 (H1R), which mediates the allergic reaction. Inverse agonists may be more potent than neutral antagonists, as they bind the same receptor as the agonist (HIS) but stabilize the inactive form and induce an opposite pharmacological response, suppressing the basal activity of H1R and preventing HIS from binding. This study aims to establish and validate a model of HIS-induced inflammation based on fully reconstituted human nasal epithelial tissue to assess the activity of FEX as an inverse agonist in this model and explore its link to clinical benefit.

Methods

The model was developed using nasal MucilAir™ (Epithelix) in vitro epithelium challenged by HIS. Two conditions were assessed in a side-by-side comparison: tissue was exposed to HIS + FEX with or without FEX pre-treatment (one-hour prior to HIS challenge). Tissue functionality, cytotoxicity, H1R gene expression, and inflammatory cytokines were assessed.

Results

HIS at 100 µM induced significant 3.1-fold and 2.2-fold increases for inflammatory biomarkers interleukin (IL)-8 and IL-6, respectively (p < 0.0001), as well as rapid upregulation of H1R mRNA. Inflammatory biomarkers were inhibited by FEX and H1R expression was significantly reduced (p < 0.0001). FEX alone decreased H1R expression at all doses tested. With one-hour FEX pre-treatment, there was significantly higher downregulation of IL-8 (p < 0.05) and further downregulation of H1R expression and IL-6 versus without FEX pre-treatment; the effects of FEX were improved from 22% to 40%.

Conclusion

A model of HIS-induced airway inflammation was established based on IL-8, IL-6 and H1R gene expression and was validated with FEX. FEX works as an inverse agonist, with a higher effect when used before+during versus only during the HIS challenge. Taking FEX before+during allergen exposure, or when symptoms first occur, may reduce basal activity and H1R gene expression, providing stronger protection against the worsening of symptoms upon allergen exposure.

Nano-Spray-Dried Levocetirizine Dihydrochloride with Mucoadhesive Carriers and Cyclodextrins for Nasal Administration

Antihistamines such as levocetirizine dihydrochloride (LC) are commercially used in oral tablets and oral drops to reduce allergic symptoms. In this study, LC was nano-spray-dried using three mucoadhesive polymers and four cyclodextrin species to form composite powders for nasal administration. The product was composed of hydroxypropyl methylcellulose polymer, including LC as a zwitterion, after neutralization by NaOH, and XRD investigations verified its amorphous state. This and a sulfobutylated-beta-cyclodextrin sodium salt-containing sample showed crystal peaks due to NaCl content as products of the neutralization reaction in the solutions before drying. The average particle size of the spherical microparticles was between 2.42 and 3.44 µm, except for those containing a polyvinyl alcohol excipient, which were characterized by a medium diameter of 29.80 µm. The drug was completely and immediately liberated from all the samples at pH 5.6 and 32 °C; i.e., the carriers did not change the good dissolution behavior of LC. A permeability test was carried out by dipping the synthetic cellulose ester membrane in isopropyl myristate using modified horizontal diffusion cells. The spray-dried powder with β-cyclodextrin showed the highest permeability (188.37 µg/cm²/h), as this additive was the least hydrophilic. Products prepared with other cyclodextrins (randomly methylated-beta-cyclodextrin, sulfobutylated-beta-cyclodextrin sodium salt and (hydroxypropyl)-beta-cyclodextrin) showed similar or slightly higher penetration abilities than LC. Other polymer excipients resulted in lower penetration of the active agent than the pure LC.

Patho-Pharmacological Research of Anti-allergic Natural Products Targeting Antihistamine-Sensitive and -Insensitive Allergic Mechanisms

Histamine H₁ receptor (H1R) has a special up-regulation mechanism by the stimulation of H1R, mediated by protein kinase C-delta (PKCδ) signaling and H1R gene expression, resulting increase in H1R signaling. Increase in H1R mRNA in nasal mucosa was induced after the provocation of nasal hypersensitivity model rats and suppressed by the pre-treatment of antihistamines. Improvement of nasal symptoms and suppression of H1R mRNA expression in nasal mucosa were also observed by the pre-treatment of antihistamines in pollinosis patients. Elucidation of a correlation between symptoms and H1R mRNA level suggests that H1R gene is an allergic disease (AD)-susceptibility gene, targeted by antihistamines. Similar to antihistamines, pre-treatment of Kujin extract, an anti-allergic Kampo medicine improved nasal symptoms and suppressed H1R mRNA expression in nasal hypersensitivity model rats. (-)-Maackiain targeting heat shock protein 90 (Hsp90) was isolated as an inhibitor of PKCδ signaling-mediated H1R gene expression from Kujin extract. In addition to H1R-mediated activation of H1R gene expression as the first mechanism, nuclear factor of activated T-cells (NFAT)-mediated IL-9 gene expression is suggested to participate to allergic symptoms as the second mechanism insensitive to antihistamines. Pyrogallol and proanthocyanidin suppressing IL-9 gene expression were discovered from Awa-tea and lotus root knots, respectively. Combination therapy using medicines suppressing both H1R gene expression and IL-9 gene expression is promising for outstanding alleviation of AD. Multifactorial diseases involving H1R gene expression may be treated by the combination therapy with antihistamine and complementary drugs, and diseases involving PKCδ signaling may be treated by drugs targeting Hsp90.

Signaling Pathway of Histamine H1 Receptor-Mediated Histamine H1 Receptor Gene Upregulation Induced by Histamine in U-373 MG Cells

Histamine H₁ receptor (H1R) is one of the targets of histamine in the nervous system and the peripheral tissues. Protein kinase Cδ (PKCδ) signaling is involved in histamine-induced upregulation of H1R gene expression in HeLa cells. Histamine also upregulates H1R gene expression in U-373 MG cells. However, the molecular signaling of this upregulation is still unclear. Here, we investigated the molecular mechanism of histamine-induced H1R gene upregulation in U-373 MG cells. Histamine-induced H1R gene upregulation was inhibited by H1R antagonist d-chlorpheniramine, but not by ranitidine, ciproxifan, or JNJ77777120, and H2R, H3R, or H4R antagonists, respectively. Ro-31-8220 and Go6976 also suppressed this upregulation, however, the PKCδ selective inhibitor rottlerin and the PKCβ selective inhibitor Ly333531 did not. Time-course studies showed distinct kinetics of H1R gene upregulation in U-373 MG cells from that in HeLa cells. A promoter assay revealed that the promoter region responsible for H1R gene upregulation in U-373 MG cells was different from that of HeLa cells. These data suggest that the H1R-activated H1R gene expression signaling pathway in U-373 MG cells is different from that in HeLa cells, possibly by using different promoters. The involvement of PKCα also suggests that compounds that target PKCδ could work as peripheral type H1R-selective inhibitors without a sedative effect.

Effects of corticosteroid on mRNA levels of histamine H1 receptor in nasal mucosa of healthy participants and HeLa cells

The purpose of this study is to examine the effect of intranasal corticosteroid (INCS) administration on histamine H1 receptor (H1R) gene expression in the nasal mucosa of healthy participants and the effects of dexamethasone on basal and histamine-induced H1R mRNA expression, and histamine-induced phosphorylation of extracellular signal-regulated kinase (ERK) in HeLa cells. Sixteen healthy participants were given INCS once daily for a week. After pretreatment of dexamethasone, HeLa cells were treated with histamine. Levels of H1R mRNA and phosphorylation of ERK were measured using real time PCR and immunoblot analysis, respectively. Levels of H1R mRNA in the nasal mucosa of healthy participants receiving INCS was significantly decreased. Dexamethasone suppressed basal levels of H1R mRNA, and histamine-induced up-regulation of H1R mRNA and ERK phosphorylation in HeLa cells. These data suggested that corticosteroid inhibited both basal transcription and histamine-induced transcriptional activation of H1R through its suppression of ERK phosphorylation in the signaling pathway involved in H1R gene transcription. It is further suggested that pre-seasonal prophylactic administration of INCS suppresses both basal and pollen-induced upregulation of H1R gene expression in the nasal mucosa of patients with pollinosis, leading to prevention of the exacerbation of nasal symptoms during peak pollen season. J. Med. Invest. 67 : 311-314, August, 2020.

Elucidation of Inverse Agonist Activity of Bilastine

H₁-antihistamines antagonize histamine and prevent it from binding to the histamine H₁ receptor (H1R). Some of them also act as inverse agonists, which are more potent than pure antagonists because they suppress the constitutive H1R activity. Bilastine is a non-sedative antihistamine which is one of the most satisfy the requirements for oral antihistamines. However, there is no information to show the inverse agonist activity of bilastine including inositol phosphates accumulation, and its inverse agonist activity is yet to be elucidated. Here we evaluated whether bilastine has inverse agonist activity or not. Intracellular calcium concentration was measured using Fluo-8. Inositol phosphates accumulation was assayed using [³H]myo-inositol. The H1R mRNA level was measured using real-time RT-PCR. At rest, Ca²⁺ oscillation was observed, indicating that H1R has intrinsic activity. Bilastine attenuated this fluorescence oscillation. Bilastine suppressed the increase in IPs formation in a dose-dependent manner and it was about 80% of the control level at the dose of 3 μM. Bilastine also suppressed histamine-induced increase in IPs formation to the control level. Furthermore, bilastine suppressed basal H1R gene expression in a dose-dependent manner. Data suggest that bilastine is an inverse agonist. Preseasonal prophylactic administration with bilastine could down-regulate basal H1R gene expression in the nasal mucosa and ameliorate the nasal symptoms during the peak pollen period.

Identification of pyrogallol from Awa-tea as an anti-allergic compound that suppresses nasal symptoms and IL-9 gene expression

As the expression level of allergic disease sensitive genes are correlated with the severity of allergic symptoms, suppression of these gene expressions could be promising therapeutics. We demonstrated that protein kinase Cδ / heat shock protein 90-mediated H1R gene expression signaling and nuclear factor of activated T-cells (NFAT)-mediated IL-9 gene expression signaling are responsible for the pathogenesis of pollinosis. Treatment with Awa-tea combined with wild grape hot water extract suppressed these signaling and alleviated nasal symptoms in toluene-2,4-diisocyanate (TDI)-sensitized rats. However, the underlying mechanism of its anti-allergic activity is not elucidated yet. Here, we sought to identify an anti-allergic compound from Awa-tea and pyrogallol was identified as an active compound. Pyrogallol strongly suppressed ionomycin-induced up-regulation of IL-9 gene expression in RBL-2H3 cells. Treatment with pyrogallol in combination with epinastine alleviated nasal symptoms and suppressed up-regulation of IL-9 gene expression in TDI-sensitized rats. Pyrogallol itself did not inhibit calcineurin phosphatase activity. However, pyrogallol suppressed ionomycin-induced dephosphorylation and nuclear translocation of NFAT. These data suggest pyrogallol is an anti-allergic compound in Awa-tea and it suppressed NFAT-mediated IL-9 gene expression through the inhibition of dephosphorylation of NFAT. This might be the underlying mechanism of the therapeutic effects of combined therapy of pyrogallol with antihistamine. J. Med. Invest. 67 : 289-297, August, 2020.

Histamine H1 Receptor Gene Expression and Drug Action of Antihistamines

The upregulation mechanism of histamine H₁ receptor through the activation of protein kinase C-δ (PKCδ) and the receptor gene expression was discovered. Levels of histamine H₁ receptor mRNA and IL-4 mRNA in nasal mucosa were elevated by the provocation of nasal hypersensitivity model rats. Pretreatment with antihistamines suppressed the elevation of mRNA levels. Scores of nasal symptoms were correlatively alleviated to the suppression level of mRNAs above. A correlation between scores of nasal symptoms and levels of histamine H₁ receptor mRNA in the nasal mucosa was observed in patients with pollinosis. Both scores of nasal symptoms and the level of histamine H₁ receptor mRNA were improved by prophylactic treatment of antihistamines. Similar to the antihistamines, pretreatment with antiallergic natural medicines showed alleviation of nasal symptoms with correlative suppression of gene expression in nasal hypersensitivity model rats through the suppression of PKCδ. Similar effects of antihistamines and antiallergic natural medicines support that histamine H₁ receptor-mediated activation of histamine H₁ receptor gene expression is an important signaling pathway for the symptoms of allergic diseases. Antihistamines with inverse agonist activity showed the suppression of constitutive histamine H₁ receptor gene expression, suggesting the advantage of therapeutic effect.

Unbearable Pruritus After Withdrawal of (Levo)cetirizine

Twelve cases of unbearable pruritus several days after withdrawal of (levo)cetirizine were reported to the Netherlands Pharmacovigilance Centre Lareb. Eleven reports concerned women and one report concerned a man, aged 19–58 years. These patients had been using these antihistamines continuously for months or years. They had tried to stop using antihistamines on several occasions but felt unable to withdraw the drug because of the unbearable maddening itch. Finally, slowly tapering the drug or using a short course of corticosteroids helped to withdraw (levo)cetirizine. The Naranjo assessment score ranged from two to four for all the cases, indicating a possible relationship.