Combination treatment for allergic conjunctivitis – Plant derived histidine decarboxylase inhibitor and H1 antihistaminic drug

Rapidly and accurately screening histidine decarboxylase inhibitors from Radix Paeoniae alba using ultrafiltration-high performance liquid chromatography/mass spectrometry combined with enzyme channel blocking and directional enrichment technique

Histidine Decarboxylase (HDC), an unique enzyme responsible for the synthesis of histamine, which is an important mediator in allergy. Inhibition of HDC activity to decrease histamine production is one way to alleviate allergic symptoms. Traditional Chinese medicines (TCMs) with reported anti-allergy effect is one of important source to search for natural HDC inhibitor. Ultrafiltration combined with high-performance liquid chromatography/mass spectrometry (UF-HPLC/MS) is an effective method for screening HDC inhibitor from TCMs. Nevertheless, false-positive and false-negative results caused by the non-specific binding and the neglection of the trace active compounds are major problems in this method. In this study, an integrated strategy that combined UF-HPLC/MS with enzyme channel blocking (ECB) technique and directional enrichment (DE) technique was developed to seek natural HDC inhibitors from Radix Paeoniae alba (RPA), and at the same time, to reduce false-positive and false-negative results. HDC activity was detected to determine the validity of the screened compounds by RP-HPLC-FD in vitro. Molecular docking was applied to assay the binding affinity and binding sites. As a result, three compounds were screened from low content components of RPA after the DE. Among them, two non-specific compounds were eliminated by ECB, and the specific compound was identified as catechin, which has obvious HDC inhibition activity with IC₅₀ 0.52 mM. Furthermore, gallic acid (IC₅₀ 1.8 mM) and paeoniflorin (IC₅₀>2 mM) from high content components of RPA were determined having HDC inhibitory activity. In conclusion, the integrated strategy of UF-HPLC/MS combined with ECB and DE technique is an effective mode for rapid and accurate screening and identification of natural HDC inhibitors from TCMs.

Ameliorative Effect of a Neoteric Regimen of Catechin plus Cetirizine on Ovalbumin-Induced Allergic Rhinitis in Rats

Allergic rhinitis (AR) affects 20–50% of the global population. Available treatments are limited by their adverse effects. We investigated the anti-allergic effects of catechin alone and combined with cetirizine against ovalbumin-induced AR. Rats were sensitized with ovalbumin and received catechin (14 days) and then challenged with aerosolized ovalbumin (1%) to determine AR clinical scores. Histamine, histamine release, and histidine decarboxylase (HDC) activity were determined in blood, peritoneal mast cells, and stomachs, respectively. Vascular permeability and safety were assessed using Evans blue leakage and barbiturate-induced sleeping-time assays, respectively. Catechin and cetirizine binding with HDC was investigated by docking and binding energy analyses. The clinical scores of the combination regimen were superior to either drug alone. All treatments reduced vascular leakage, with no effect on barbiturate-induced sleeping time. Only the catechin-treated rats showed reduced histamine levels and HDC activity. Docking studies revealed that catechin has a 1.34-fold higher extra-precision docking score than L-histidine. The binding energy scores for catechin-HDC, L-histidine-HDC, and histamine-HDC were −50.86, −37.64, and −32.27 kcal/mol, respectively. The binding pattern of catechin was comparable to the standard HDC inhibitor, histidine methyl ester, but with higher binding free energy. Catechin binds the catalytic residue S354, unlike cetirizine. The anti-allergic effects of catechin can be explained by HDC inhibition and possible antihistaminic activity.

Anti-anaphylactic potential of benzoylpaeoniflorin through inhibiting HDC and MAPKs from Paeonia lactiflora

Guided by cell-based anti-anaphylactic assay, eighteen cage-like monoterpenoid glycosides (1-18) were obtained from the bioactive fraction of P. lactiflora extract. Among these, compounds 1, 5, 6, 11, 12, 15, and 17 significantly reduced the release rate of β-HEX and HIS without or with less cytotoxicity. Furthermore, the most potent inhibitor benzoylpaeoniflorin (5) was selected as the prioritized compound for the study of action of mechanism, and its anti-anaphylactic activity was medicated by dual-inhibiting HDC and MAPK signal pathway. Moreover, molecular docking simulation explained that benzoylpaeoniflorin (5) blocked the conversion of L-histidine to HIS by occupying the HDC active site. Finally, in vivo on PCA using BALB/c mice, benzoylpaeoniflorin (5) suppressed the IgE-mediated PCA reaction in antigen-challenged mice. These findings indicated that cage-like monoterpenoid glycosides, especially benzoylpaeoniflorin (5), mainly contribute to the anti-anaphylactic activity of P. lactiflora by dual-inhibiting HDC and MAPK signal pathway. Therefore, benzoylpaeoniflorin (5) may be considered as a novel drug candidate for the treatment of anaphylactic diseases.

Ocular allergy: update on clinical trials

PURPOSE OF REVIEW

The purpose of this article is to provide an update on the advances made through recent clinical trials regarding the treatment of the signs and symptoms of allergic conjunctivitis and its associated conditions.

RECENT FINDINGS

Recent studies have demonstrated significant advancement in the various forms of immunotherapy treatments. Nutritional interventions such as probiotics have surfaced as a viable complementary treatment option. Novel delivery methods such as contact lenses have been further studied along with a new tacrolimus formulation to improve ocular levels of the drug.

SUMMARY

Currently, the primary advances in treatment for allergic conjunctivitis has shifted from new ophthalmic agents to immunotherapy and improvement of drug delivery. This includes the classic subcutaneous and sublingual and the novel epicutaneous and intralymphatic immunotherapy delivery systems as well as an edible rice vaccine. New targets for treatment have spurred research into new antagonist drugs such as (OC000459), a prostaglandin D2 antagonist. The Marinosolv formulation using tacrolimus shows promise and may be considered for other ophthalmic agents in the future. Other nonpharmacological treatments such as stenting and mechanical barrier gel have demonstrated their usefulness in treating ocular symptoms.

Acute and 28-days repeated dose sub-acute toxicity study of gallic acid in albino mice

Gallic acid is a phenolic acid ubiquitously present in numerous medicinal plants and food beverages. Gallic acid is also a potent anti-oxidant phytochemical possessing numerous medicinal potentials against various ailments such as diabetes, hypercholesterolemia and other life-threatening diseases including malignancy. Present study was aimed to evaluate acute and sub-acute toxicity of gallic acid in albino mice. The primary aim of the study was to investigate gallic acid prompted PPAR-α/γ activation associated adverse events. Acute toxicity of gallic acid was determined in albino mice and 28-days sub-acute toxicity study was carried out in male and female albino mice at three dose levels, 100, 300 and 900 mg/kg/day, p.o. LD₅₀ of gallic acid was found to be greater than 2000 mg/kg in mice. Hematological investigation did not show any alteration in transaminases and other blood homeostasis parameters. Gross necropsy showed non-significant alteration upon gallic acid administration. Histopathological finding suggested no significant alteration in tissue histology with slight fatty cells in bone marrow indicating non-significant bone marrow suppression, also no obvious effect was observed on hematological parameters. High dose of gallic acid (900 mg/kg/day) for 28 days did not produce any significant alteration in morphological and behavioral parameters. Histopathological finding also supports safety of gallic acid in mice.

Against NF-κB/thymic stromal lymphopoietin signaling pathway, catechin alleviates the inflammation in allergic rhinitis

BACKGROUND

The prevalence of allergic rhinitis has risen sharply. Previous work has demonstrated the anti-inflammatory effect of catechin, including in models of allergic disease. However, the molecular mechanisms underlying this therapeutic effect remain unclear. Thymic stromal lymphopoietin(TSLP), as a molecule from epithelial cell, has been identified that plays a significant role in the development of allergic disease, and the production of TSLP is related to activation of the NF-κB signaling pathway. For that, we try to research the treatment of catechin for allergic rhinitis and found out possible mechanism under this effect, which was based on TSLP factor.

MATERIALS AND METHODS

Here, the anti-inflammatory effects of catechin were studied in an ovalbumin-induced allergic rhinitis murine model and a vitro experiments using poly(I:C)-stimulated human nasal epithelial cells(HNEpCs). The pharmacological effects of catechin in allergic rhinitis mice were assessed by observing the allergic symptoms, performing hematoxylin and eosin staining and Giemsa staining of the nasal tissues. Additionally, the TSLP expression in epithelial cells was tested by enzyme-linked immunosorbent assays, immunohistochemistry, and western blots. The serum levels of interleukin-5, interleukin-13, and ovalbumin-specific immunoglobulin-E were detected by enzyme-linked immunosorbent assays, and the balance between T helper type 1 and T helper type 2 cells was assessed by flow cytometry. The expression levels of phospho-NF-κBp65, IκBα, and NF-κBp65 proteins were further investigated by western blots or immunofluorescence.

RESULTS

Our results reveal that catechin, in doses of 75, 150, or 300 mg/kg, remitted the allergic symptoms in mice with allergic rhinitis, like sneezing and nasal rubbing. Catechin could reduce the levels of interleukin-5, interleukin-13, and ovalbumin-specific immunoglobulin-E in the serum and restored the T helper type 2/T helper type 1 cell balance and also had anti-thymic stromal lymphopoietin effects. Moreover, as an upstream regulator of TSLP, the NF-κB signal pathway was also suppressed after catechin treatment, which was demonstrated by the observed decrease in phospho-NF-κBp65 and NF-κBp65 levels and the reduction of IκBα degradation and NF-κBp65 nuclear translocation.

CONCLUSIONS

Catechin effectively reduced the inflammation in allergic rhinitis. The underlying mechanism is that catechin inhibited the expression of TSLP in epithelial cells by influencing NF-κB/TSLP pathway.

DEAE-Dextran coated paclitaxel nanoparticles act as multifunctional nano system for intranuclear delivery to triple negative breast cancer through VEGF and NOTCH1 inhibition

Triple negative breast cancer revolution has identified a plethora of therapeutic targets making it apparent that a single target for its treatment could be rare hence creating an urge to develop robust technologies for combination drug therapy. Paclitaxel, hailed as the most significant advancement in chemotherapy faces several underpinnings due to its low solubility and permeability. Advancing research has demonstrated the role of interferons in cancer. DEAE-Dextran, an emerging molecule with evidence of interferon induction was utilized in the present study to develop a nanoformulation in conjugation with paclitaxel to target multiple therapeutic pathways, with diminution of paclitaxel adverse effects and develop a specific targeted nano system. Evidently, it was demonstrated that DEAE-Dextran coated nanoformulation portrays significant synergistic cytotoxicity in the various cell lines. Moreover, overcoming the activation of ROS by paclitaxel, the combination drug therapy more effectively inhibited ROS through β-interferon induction. The nanoformulation was further conjugated to FITC for internalization studies which subsequently indicated maximum cellular uptake at 60min post treatment demonstrated by green fluorescence from FITC lighting up the nuclear membrane. Precisely, the mechanistic approach of nuclear-targeted nanoformulation was evaluated by in vivo xenograft studies which showed a synergistic release of β-interferon at the target organ. Moreover, the combination nanoformulation inculcated multiple mechanistic approaches through VEGF and NOTCH1 inhibition along with dual β and γ-interferon overexpression. Overall, the combination therapy may be a promising multifunctional nanomaterial for intranuclear drug delivery in TNBC.

Pinocembrin, a novel histidine decarboxylase inhibitor with anti-allergic potential in in vitro

Pinocembrin (5, 7- dihydroxy flavanone) is the most abundant chiral flavonoid found in propolis, exhibiting antioxidant, antimicrobial and anti-inflammatory properties. However, the effect of Pinocembrin on allergic response is unexplored. Thus, current study aimed at investigating the effects of Pinocembrin on IgE-mediated allergic response in vitro. A special emphasis was directed toward histidine decarboxylase (HDC) and other pro-allergic and pro-inflammatory mediators. Preliminary studies, using a microbiological model of Klebsiella pneumoniae, provided first evidences that suggest Pinocembrin as a potential thermal stable inhibitor for HDC. Applying docking analysis revealed possible interaction between Pinocembrin and mammalian HDC. In vitro studies validated the predicted interaction and showed that Pinocembrin inhibits HDC activity and histamine in IgE-sensitized RBL-2H3 in response to dinitrophenol (DNP)-bovine serum albumin (BSA) stimulation. In addition, Pinocembrin mitigated the damage in the mitochondrial membrane, formation of cytoplasmic granules and degranulation as indicated by lower β-hexoseaminidase level. Interestingly, it reduced range of pro-inflammatory mediators in the IgE-mediated allergic response including tumor necrosis factor (TNF)-α, interleukin (IL)-6, nitric oxide (NO), inducible NO synthase (iNOS), phosphorylation of inhibitory kappa B (IкB)-α, prostaglandin (PGE)-2 and cyclooxygenase (COX)-2. In conclusion, current study suggests Pinocembrin as a potential HDC inhibitor, and provides the first evidences it is in vitro anti-allergic properties, suggesting Pinocembrin as a new candidate for natural anti-allergic drugs.