Oleanolic acid controls allergic and inflammatory responses in experimental allergic conjunctivitis

Triterpenoids from Frankincense and Boswellia: A focus on their pharmacology and 13C-NMR assignments

Here we report for the first time the entire 13C-NMR spectral assignments of 119 (out of 127) triterpenoids from the oleo-gum resins of the medicinally important genus Boswellia, which includes the culturally highly valuable Frankincense species. The complete 13C-NMR resonances of these triterpenoids isolated between 1998 and 2024 and their biological activities are presented. 13C-NMR spectroscopy is a highly powerful tool for the characterization of these bioactive natural products. The compounds are arranged according to their skeletons, i.e., ursane, oleanane, lupane, dammarane, and tirucallane triterpenes. This review will be a future reference for the identification of these compounds, which have key medicinal properties in the areas of cytotoxicity and inflammation.

The NLRP3 inflammasome in allergic diseases: mechanisms and therapeutic implications

In recent years, there has been a global increase in the prevalence of allergic diseases, including allergic rhinitis, chronic rhinosinusitis, allergic asthma, atopic dermatitis, allergic conjunctivitis, and food allergies. Since the pathogenic mechanisms of these allergic diseases are not yet fully understood, targeted and effective therapies are lacking. The NLRP3 inflammasome, a multiprotein complex implicated in various inflammatory diseases, can be activated by diverse stimuli. It assembles into NLRP3 inflammasome complexes through conformational changes, initiating the proteolytic cleavage of dormant procaspase-1 into active caspase-1 and promoting the maturation of inflammatory cytokines, including IL-1β and IL-18. Dysfunction of the NLRP3 inflammasome may serve as a key driver of inflammatory diseases, leading to pyroptosis and amplifying the local inflammatory response. As preliminarily demonstrated, specific NLRP3 inflammatory vesicle inhibitors play refectory roles in animal models of allergic diseases, and it is believed that specific NLRP3 inflammasome inhibitors may be potential therapeutic agents for allergic diseases. This review highlights the progress of research on the NLRP3 inflammasome in allergic diseases, explores its contribution to different types of allergic diseases, and identifies promising clinical targets for intervention.

Therapeutic potential of oleanolic acid in liver diseases

Liver-associated diseases affect millions of individuals worldwide. In developed countries, the incidence of viral hepatitis is reducing due to advancements in disease prevention, diagnosis, and treatment. However, with improvements in living standards, the prevalence of metabolic liver diseases, such as non-alcoholic fatty liver disease and alcohol-related liver disease, is expected to increase; notably, this rise in the prevalence of metabolic liver disease can lead to the development of more severe liver diseases, including liver failure, cirrhosis, and liver cancer. The growing demand for natural alternative therapies for chronic diseases has highlighted the importance of studying the pharmacology of bioactive compounds in plants. One such compound is oleanolic acid (OA), a pentacyclic triterpenoid known for its antioxidant, anti-inflammatory, anti-ulcer, antibacterial, antiviral, antihypertensive, anti-obesity, anticancer, anti-diabetic, cardioprotective, hepatoprotective, and anti-neurodegenerative properties. Recent studies have demonstrated that OA treatment can reduce the risk of pathological liver damage, ultimately alleviating liver dysregulation and restoring overall liver function. This review aims to explore the latest research on the biological effects of OA and its derivatives. Notably, it explores the mechanisms of action of these compounds in both in vitro and in vivo research models and, ultimately, highlights OA as a promising candidate for alternative therapies in the treatment and management of chronic liver disease.

Crosstalk between Myopia and Inflammation: A Mini Review

Myopia represents a significant public health concern worldwide, particularly affecting the ocular health of children and adolescents. The escalating prevalence of myopia in recent years underscores its urgency as a health issue among this demographic. Research indicates a profound connection between the onset of myopia, inflammatory processes and fibrosis. Individuals with inflammatory conditions like allergic conjunctivitis, choroiditis, systemic lupus erythematosus, and diabetes exhibit a heightened susceptibility to myopia. Conversely, myopic patients are at an increased risk of developing ocular inflammatory disorders, notably idiopathic multifocal choroiditis. We postulate that the expression of inflammatory markers, including NF-κB, TGF-β, IL-1β, IL-6, IL-8, and TNF-α, may contribute to the chronic inflammatory state observed in myopia. This paper highlights a substantial correlation between myopia and inflammation, suggesting the potential efficacy of anti-inflammatory agents in managing inflammation and slowing myopia progression.

Therapeutic effects of Pulsatilla koreana Nakai extract on ovalbumin-induced allergic rhinitis by inhibition of Th2 cell activation and differentiation via the IL-4/STAT6/GATA3 pathway

Allergic rhinitis (AR), caused by immunoglobulin E (IgE)-mediated inflammation, generally occurs in the upper respiratory tract. T helper type 2 (Th2) cell-mediated cytokines, including interleukin (IL)-4, IL-5, and IL-13, are important factors in AR pathogenesis. Despite various treatment options, the difficulty in alleviating AR and pharmacological side effects necessitate development of new therapies. The root of Pulsatilla koreana Nakai (P. koreana), a pasque flower, has been used as a herbal medicine. However, its effects on AR remain unclear; therefore, we aimed to explore this subject in the current study. The therapeutic effects of P. koreana water extract (PKN) on the pathophysiological functions of the nasal mucosa was examined in ovalbumin (OVA)-induced AR mice. The effect of PKN on Th2 activation and differentiation was evaluated using concanavalin A-induced splenocytes and differentiated Th2 cells from naïve CD4⁺ T cells. We also investigated the effect of changes in JAK/STAT6/GATA3 signaling on IL-4-induced Th2 cells. In OVA-induced AR mice, PKN administration alleviated allergic nasal symptoms and decreased the total number of immune cells, lymphocytes, neutrophils, and eosinophils in nasal lavage fluid; serum levels of OVA-specific IgE, histamine, and IL-13 were also significantly reduced. PKN also ameliorated OVA-induced nasal mucosal tissue thickening by inhibiting inflammation and goblet cell hyperplasia. PKN treatment significantly inhibited Th2 activity and differentiation through the IL-4/STAT-6/GATA3 pathway in Th2 cells. PKN is an effective AR treatment with the potential to improve patients' daily lives by regulating the allergic inflammatory response induced by Th2 cells.

Oleanolic Acid Acetate Inhibits Mast Cell Activation in Ovalbumin-Induced Allergic Airway Inflammation

PURPOSE

Asthma is a complex, heterogeneous chronic inflammatory airway disease with multiple phenotypes. There has been a great progress in managing asthma, but there are still unmet needs for developing uncontrolled asthma treatments. The present study aimed to determine the effectiveness of oleanolic acid acetate (OAA) from Vigna angularis against allergic airway inflammation and the underlying mechanism of action with a focus on mast cells.

METHODS

To investigate the effect of OAA in allergic airway inflammation, we used the ovalbumin (OVA)-sensitized and challenged mice. To examine allergic airway inflammation associated with immune responses of mast cell activation in vitro, various types of mast cells were used. Systemic and cutaneous anaphylaxis models were used for mast cell-mediated hyper-responsiveness in vivo.

RESULTS

OAA reduced OVA-induced airway inflammatory responses such as bronchospasm, increase of immune cell infiltration and serum immunoglobulin E and G₁ levels. Especially, OAA decreased the mast cell infiltration, and β-hexosaminidase release as a mast cell activation marker in the bronchoalveolar lavage fluid. OAA inhibited mast cell degranulation in mast cell line (RBL-2H3) and primary cells (rat peritoneal mast cell and mouse bone marrow-derived mast cell). Mechanistically, OAA suppressed intracellular signaling pathways including the phosphorylation of phospholipase Cγ and nuclear factor-κB, resulting from the suppression of intracellular calcium influx and pro-inflammatory cytokine expression. Further, oral administration of OAA attenuated mast cell-mediated systemic and cutaneous anaphylaxis.

CONCLUSIONS

Our study showed that OAA can inhibit mast cell-mediated allergic reaction. Consequently, the application of OAA to mast cells for the allergic airway inflammation facilitate a new direction of treating allergic asthma.

Insights into isostructural and non-isostructural crystals of esters of oleanolic acid and its 11-oxo derivatives

Synthesis and structural characterization of new esters of oleanolic acid and its 11-oxo derivatives are reported. Compounds crystallize in four isostructural groups, each containing one to four structures. Single-crystal X-ray analysis revealed that molecules belonging to non-isostructural groups self-associate according to two schemes that describe also supramolecular architectures in crystals of glycyrrhetinic acid derivatives. Structural motifs arise as a result of van der Waals forces. Parameters introduced for the analysis of one- and two-dimensional assemblies allow the comparison of motifs in isostructural and non-isostructural crystals, including polymorphs, and a qualitative assessment of differences in molecular self-assembly. One-, two- or three-dimensional similarity has been confirmed by XPac calculations.

Altered retinal nerve fiber layer thickness in children with allergic conjunctivitis: the Nanjing eye study

Background

So far, few data are available on the relationship between allergic conjunctivitis (AC) and ocular fundus. Whether retinal parameters change in patients with AC remains unknown. In this study, we investigated the influence of AC on retinal thickness and vessel density among 7-years-old school-age children.

Methods

This large population-based study is part of the Nanjing Eye Study (NES). Comprehensive examinations including anthropometric parameters, refraction, ocular biometric parameters, intraocular pressure and retinal parameters were conducted on each child. Retinal thickness and vessel density were assessed using the optical coherence tomography angiography. Information on AC was obtained from a comprehensive questionnaire.

Results

A total of 739 children (mean age ± SD: 7.40 ± 0.29 years) had complete eye examination and questionnaire data we needed. Ninety-four children (12.7%) had AC, among which, 5 children had the history of corticosteroid use and were excluded from the final analysis. Spherical equivalent, axial length, body mass index and birth weight were correlated with retinal parameters. After adjusting for sex, age, spherical equivalent, axial length, body mass index, birth weight and premature history, children with AC had thinner retinal nerve fiber layer thickness for average (117.39 versus 120.97 μm, p = 0.007), temporal (80.73 versus 84.34 μm, p = 0.001), nasal (98.82 versus 102.18 μm, p = 0.049) and inferior (152.68 versus 157.06 μm, p = 0.034) quadrants than the control group.

Conclusions

Children with AC tended to have thinner retinal nerve fiber layer thickness. More attention is needed to fundus condition of children with AC.

Supplementary information

The online version contains supplementary material available at 10.1186/s12886-022-02399-7.

Formulation and Pathohistological Study of Mizolastine-Solid Lipid Nanoparticles-Loaded Ocular Hydrogels

Background

Mizolastine (MZL) is a dual-action nonsedating topical antihistamine anti-inflammatory agent that is used to relieve allergic conditions, such as rhinitis and conjunctivitis. Solid lipid nanoparticles (SLNs) are advanced delivery system in ophthalmology, with the merits of increasing the corneal drug absorption and hence improved bioavailability with the objective of ocular drug targeting.

Methods

First, MZL was formulated as MZL-SLNs by hot homogenization/ultrasonication adopting a 3² full factorial design. Solid-state characterization, in vitro release, and stability studies have been performed. Then, the optimized MZL-SLNs formula has been incorporated into ocular hydrogels using 1.5% w/v Na alginate and 5% w/v polyvinylpyrrolidone K₉₀. The gels were evaluated via in vitro release as well as in vivo studies by applying allergic conjunctivitis congestion in a rabbit-eye model.

Results

The optimized formula (F4) was characterized by the highest entrapment efficiency (86.5±1.47%), the smallest mean particle size (202.3±13.59 nm), and reasonable zeta potential (−22.03±3.65 mV). Solid-state characterization of the encapsulation of MZL in SLNs was undertaken. In vitro results showed a sustained release profile from MZL-SLNs up to 30 hours with a non-Fickian Higuchi kinetic model. Stability studies confirmed immutability of freeze-dried MZL-SLNs (F4) upon storage for 6 months. Finally, hydrogel formulations containing MZL-SLNs, proved ocular congestion disappearance with completely repaired conjunctiva after 24 hours. Moreover, pretreatment with MZL-SLNs–loaded hydrogel imparted markedly decreased TNF-α and VEGF-expression levels in rabbits conjunctivae compared with post-treatment with the same formula.

Conclusion

MZL-SLNs could be considered a promising stable sustained-release nanoparticulate system for preparing ocular hydrogel as effective antiallergy ocular delivery systems.

Immunomodulatory properties of triterpenes

The immune system is one of the main defence mechanisms of the human body. Inadequacy of this system or immunodeficiency results in increased risk of infections and tumours, whereas over-activation of the immune system causes allergic or autoimmune disorders. A well-balanced immune system is important for protection and for alleviation of these diseases. There is a growing interest to maintain a well-balanced immune system, especially after the Covid-19 pandemic. Many biological extracts, as well as natural products, have become popular due to their wide array of immunomodulatory effects and influence on the immune system. Triterpenes, one of the secondary metabolite groups of medicinal plants, exhibit immunomodulatory properties by various mechanisms. Different triterpenes, including components of commonly consumed plants, can promote some protection and alleviation of disease symptoms linked with immune responses and thus enhance overall well-being. This review aims to highlight the efficacy of triterpenes in light of the available literature evidence regarding the immunomodulatory properties of triterpenes. We have reviewed widely investigated immunomodulatory triterpenes; oleanolic acid, glycyrrhizin, glycyrrhetinic acid, pristimerin, ursolic acid, boswellic acid, celastrol, lupeol, betulin, betulinic acid, ganoderic acid, cucumarioside, and astragalosides which have important immunoregulatory properties. In spite of many preclinical and clinical trials were conducted on triterpenes related to their immunoregulatory actions, current studies have several limitations. Therefore, especially more clinical studies with optimal design is essential.

Consequences of seasonal allergic conjunctivitis on ocular parameters of anterior and posterior segments: An up-to-date imaging approach

Aims

To investigate consequences of seasonal allergic conjunctivitis (SAC) on the ocular anterior and posterior segment parameters.

Materials and Methods

Forty healthy participants (mean age: 25.90 ± 5.7 years, 20 females, 20 males) and 40 patients with SAC (mean age: 26.20 ± 5.7 years, 20 females, 20 males) were included in this prospective study. The anterior segment parameters including central corneal thickness (CCT) and anterior chamber depth (ACD) were measured by Scheimpflug imaging system. Axial length (AL) was measured by optical biometry. The posterior segment parameters, including retinal nerve fiber layer (RNFL), subfoveal choroidal thickness, and central macular thickness were measured by optical coherence tomography.

Results

Similar values of the ACD, AL, RNFL as well as central macular thickness between healthy participants and patients with SAC were revealed. Despite the CCT being thinner in SAC, there was no statistically significant difference between the two groups. On the other hand, SAC was found to be associated with an increase in subfoveal choroidal thickness, the condition of which may be attributed to the inflammatory nature of the disease.

Conclusion

The present study has managed to demonstrate non-significant alterations in the ocular anterior and posterior segment parameters of patients with SAC. Yet, the increase in subfoveal choroidal thickness may be linked to the accompanying inflammation of both the conjunctiva and other ocular tissues, particularly the choroidal layer.

Ocular redness - II: Progress in development of therapeutics for the management of conjunctival hyperemia

Conjunctival hyperemia is one of the most common causes for visits to primary care physicians, optometrists, ophthalmologists, and emergency rooms. Despite its high incidence, the treatment options for patients with conjunctival hyperemia are restricted to over-the-counter drugs that provide symptomatic relief due to short duration of action, tachyphylaxis and rebound redness. As our understanding of the immunopathological pathways causing conjunctival hyperemia expands, newer therapeutic targets are being discovered. These insights have also contributed to the development of animal models for mimicking the pathogenic changes in microvasculature causing hyperemia. Furthermore, this progress has catalyzed the development of novel therapeutics that provide efficacious, long-term relief from conjunctival hyperemia with minimal adverse effects.

Oleanolic acid protects against mast cell-mediated allergic responses by suppressing Akt/NF-κB and STAT1 activation

BACKGROUND

Oleanolic acid (OA) is an active compound found in a variety of medicinal herbs and plants. Though OA has been widely attributed with a variety of biological activities, studies focused on its anti-allergic inflammation properties are insufficient.

PURPOSE

Given the rapid increase in allergic diseases and the lack of fundamental treatment options, this study aimed to find a safe and effective therapy for allergic disorders.

METHODS

We evaluated the inhibitory effect of OA on allergic inflammatory response and the possible mechanisms underlying the effect using phorbol-12-myristate 13-acetate plus calcium ionophore A23187 (PMACI)-stimulated human mast cell (HMC)-1, and a mouse model of compound 48/80-induced anaphylactic shock.

RESULTS

OA suppressed pro-inflammatory cytokine expressions in PMACI-induced HMC-1 cells by inhibiting activation of the Akt, p38 mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), and signal transducer and activator of transcription (STAT) 1 signaling pathways. Moreover, OA showed a protective effect against compound 48/80-induced anaphylactic shock through inhibition of histamine release and immunoglobulin E level via regulation of NF-κB and STAT1 activation.

CONCLUSION

The results showed that OA suppressed mast cell-mediated allergic response by transcriptional regulation. We suggest that OA has potential effect against allergic inflammatory disorders, including anaphylaxis, and might be a useful therapeutic agent for allergic disease.

Oleanolic acid ameliorates intestinal alterations associated with EAE

Background

Multiple sclerosis (MS) is a chronic demyelinating autoimmune disease affecting the CNS. Recent studies have indicated that intestinal alterations play key pathogenic roles in the development of autoimmune diseases, including MS. The triterpene oleanolic acid (OA), due to its anti-inflammatory properties, has shown to beneficially influence the severity of the experimental autoimmune encephalomyelitis (EAE), a preclinical model of MS. We herein investigate EAE-associated gut intestinal dysfunction and the effect of OA treatment.

Methods

Mice with MOG_35–55-induced EAE were treated with OA or vehicle from immunization day and were daily analyzed for clinical deficit. We performed molecular and histological analysis in serum and intestinal tissues to measure oxidative and inflammatory responses. We used Caco-2 and HT29-MTX-E12 cells to elucidate OA in vitro effects.

Results

We found that OA protected from EAE-induced changes in intestinal permeability and preserved the mucin-containing goblet cells along the intestinal tract.

Serum levels of the markers for intestinal barrier damage iFABP and monocyte activation sCD14 were consistently and significantly reduced in OA-treated EAE mice. Beneficial OA effects also included a decrease of pro-inflammatory mediators both in serum and colonic tissue of treated-EAE mice. Moreover, the levels of some immunoregulatory cytokines, the neurotrophic factor GDNF, and the gastrointestinal hormone motilin were preserved in OA-treated EAE mice. Regarding oxidative stress, OA treatment prevented lipid peroxidation and superoxide anion accumulation in intestinal tissue, while inducing the expression of the ROS scavenger Sestrin-3. Furthermore, short-chain fatty acids (SCFA) quantification in the cecal content showed that OA reduced the high iso-valeric acid concentrations detected in EAE-mice. Lastly, using in vitro cell models which mimic the intestinal epithelium, we verified that OA protected against intestinal barrier dysfunction induced by injurious agents produced in both EAE and MS.

Conclusion

These findings reveal that OA ameliorates the gut dysfunction found in EAE mice. OA normalizes the levels of gut mucosal dysfunction markers, as well as the pro- and anti-inflammatory immune bias during EAE, thus reinforcing the idea that OA is a beneficial compound for treating EAE and suggesting that OA may be an interesting candidate to be explored for the treatment of human MS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-020-02042-6.

Prophylactic and therapeutic roles of oleanolic acid and its derivatives in several diseases

Oleanolic acid (OA) and its derivatives are widely found in diverse plants and are naturally effective pentacyclic triterpenoid compounds with broad prophylactic and therapeutic roles in various diseases such as ulcerative colitis, multiple sclerosis, metabolic disorders, diabetes, hepatitis and different cancers. This review assembles and presents the latest in vivo reports on the impacts of OA and OA derivatives from various plant sources and the biological mechanisms of OA activities. Thus, this review presents sufficient data proposing that OA and its derivatives are potential alternative and complementary therapies for the treatment and management of several diseases.

Endogenous Annexin-A1 Negatively Regulates Mast Cell-Mediated Allergic Reactions

Mast cell stabilizers like cromoglycate and nedocromil are mainstream treatments for ocular allergy. Biochemical studies in vitro suggest that these drugs prevent mast cell degranulation through the release of Annexin-A1 (Anx-A1) protein. However, the direct effect of Anx-A1 gene deletion on mast cell function in vitro and in vivo is yet to be fully investigated. Hence, we aim to elucidate the role of Anx-A1 in mast cell function, both in vivo and in vitro, using a transgenic mouse model where the Anx-A1 gene has been deleted. Bone marrow-derived mast cells (BMDMCs) were cultured from wild-type animals and compared throughout their development to BMDMCs obtained from mice lacking the Anx-A1 gene. The mast cell differentiation, maturity, mediator, and cytokine release were explored using multiple biochemical techniques, such as Western blots, ELISA, and flow cytometry analysis. Electron microscopy was used to identify metachromatic granules content of cells. For in vivo studies, Balb/C wild-type and Anx-A1-deficient mice were divided into the following groups: group 1, a control receiving only saline, and group 2, which had been sensitized by prior exposure to short ragweed (SRW) pollen by topical contact with the conjunctival mucosae. Allergic conjunctivitis was evaluated blind after 24 h by trained observers scoring clinical signs. Electron micrographs of BMDMCs from Anx-A1-null mice revealed more vacuoles overall and more fused vacuoles than wild-type cells, suggesting enhanced secretory activity. Congruent with these observations, BMDMCs lacking the Anx-A1 gene released significantly increased amounts of histamine both spontaneously as well as in response to Ig-E-FcεRI cross-linking compared to those from wild-type mice. Interestingly, the spontaneous release of IL-5, IL-6, IL-9, and monocyte chemoattractant protein-1 (MCP-1) were also markedly increased with a greater production observed upon IgE cross-linking. This latter finding is congruent with augmented calcium mobilization in BMDMCs lacking the Anx-A1 gene. In vivo, when compared to wild-type animals, Anx-A1-deficient mice exposed to SRW pollen displayed exacerbated signs and symptoms of allergic conjunctivitis. Taken together, these results suggest Anx-A1 is an important non-redundant regulator of mast cell reactivity and particularly in allergen mediated allergic reactions.

A Murine Model of Acute Allergic Conjunctivitis Induced by Continuous Exposure to Particulate Matter 2.5

Purpose

Several pieces of epidemiologic evidence have indicated PM2.5 (particulate matter with a diameter of 2.5 μm or less) as a causing factor of allergic conjunctivitis, but without experimental elucidation of mechanism. In the present study, PM2.5 in solution was directly applied to the mouse ocular surface to elucidate whether PM2.5 might cause allergic conjunctivitis, and its underlying mechanisms were analyzed.

Methods

ICR mice were challenged for 18 consecutive days with eye drops containing PM2.5 at 3.2, 6.4, and 12.8 mg/mL in 0.9% NaCl saline, along with the controls prepared in parallel without PM2.5 and another control group treated with both PM2.5 at 12.8 mg/mL and artificial tears. On day 19, the whole eyes and meibomian glands were harvested for histopathological analyses and assessment of clinical scoring, tear volume, tear breakup time, and tear ferning. Furthermore, goblet cells by periodic acid Schiff stain and infiltrated eosinophils by Giemsa stain were quantified and compared among study groups.

Results

Clinical scoring showed more eyelid edema, tearing, and scratching behaviors, with longer tear breakup time under the influence of increased PM2.5 concentrations. Tear ferning assay showed less tear crystal formation and decreased crystal branches after exposure to PM2.5. In addition, higher goblet cell density in the upper palpebral conjunctiva and extensive eosinophil infiltration in the entire conjunctiva and in the meibomian glands were induced by PM2.5.

Conclusions

These results demonstrate that PM2.5 can induce symptoms similar to clinical allergic conjunctivitis and that the murine acute allergic conjunctivitis model can be induced by direct exposure to PM2.5.

Study of the anti-allergic and anti-inflammatory activity of Brachychiton rupestris and Brachychiton discolor leaves (Malvaceae) using in vitro models

Background

Brachychiton rupestris and Brachychiton discolor (Malvaceae) are ornamental trees native to Australia. Some members of Brachychiton and its highly related genus, Sterculia, are employed in traditional medicine for itching, dermatitis and other skin diseases. However, scientific studies on these two genera are scarce. Aiming to reveal the scientific basis of the folk medicinal use of these plants, the cytotoxicity, anti-inflammatory and anti-allergic activities of Brachychiton rupestris and Brachychiton discolor leaves extracts and fractions were evaluated. Also, phytochemical investigation of B. rupestris was performed to identify the compounds exerting the biological effect.

Methods

Extracts as well as fractions of Brachychiton rupestris and Brachychiton discolor were tested for their cytotoxicity versus hepatoma HepG2, lung A549, and breast MDA-MB-231 cancer cell lines. Assessment of the anti-allergic activity was done using degranulation assay in RBL-2H3 mast cells. Anti-inflammatory effect was tested by measuring the suppression of superoxide anion production as well as elastase release in fMLF/CB-induced human neutrophils. Phytochemical investigation of the n-hexane, dichloromethane and ethyl acetate fractions of B. rupestris was done using different chromatographic and spectroscopic techniques.

Results

The tested samples showed no cytotoxicity towards the tested cell lines. The nonpolar fractions of both B. rupestris and B. discolor showed potent anti-allergic potency by inhibiting the release of β-hexosaminidase. The dichloromethane fraction of both species exhibited the highest anti-inflammatory activity by suppressing superoxide anion generation and elastase release with IC₅₀ values of 2.99 and 1.98 μg/mL, respectively for B. rupestris, and 0.78 and 1.57 μg/mL, respectively for B. discolor. Phytochemical investigation of various fractions of B. rupestris resulted in the isolation of β-amyrin acetate (1), β-sitosterol (2) and stigmasterol (3) from the n-hexane fraction. Scopoletin (4) and β-sitosterol-3-O-β-D-glucoside (5) were obtained from the dichloromethane fraction. Dihydrodehydrodiconiferyl alcohol 4-O-β-D-glucoside (6) and dihydrodehydrodiconiferyl alcohol 9-O-β-D-glucoside (7) were separated from the ethyl acetate fraction. Scopoletin (4) showed anti-allergic and anti-inflammatory activity.

Conclusions

It was concluded that the nonpolar fractions of both Brachychiton species exhibited anti-allergic and anti-inflammatory activities.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2359-6) contains supplementary material, which is available to authorized users.

Role of Oleanolic acid in maintaining BBB integrity by targeting p38MAPK/VEGF/Src signaling pathway in rat model of subarachnoid hemorrhage

Vasogenic brain edema after subarachnoid hemorrhage (SAH) is an independent risk factor for death and poor prognosis. Disruption of the blood-brain barrier (BBB) is the main cause of vasogenic brain edema induced by SAH. Oleanolic acid (OA) is a natural pentacyclic triterpenoid with various biological functions. Previous studies have shown that prophylactic administration of OA could prevent the BBB disruption in autoimmune encephalomyelitis mice. In this context, we speculate that OA may play a neuroprotective role by protecting the integrity of the BBB and reducing vasogenic cerebral edema after SAH. To validate this hypothesis, a SAH model was established on Sprague Dawley rats using a standard intravascular puncture model. The effects of OA on various physiological indexes were observed, including SAH grades, mortality, neurological function score, brain edema and BBB permeability. Related proteins of the brain endothelial cell junction complex were also detected, including tight junctions (TJs) and adherent junctions (AJs). Results showed that OA significantly reduced the permeability of BBB and relieved brain edema by increasing protein expression of TJs and AJs, and decreased the SAH grades by increasing the protein expression of heme oxygenase-1 (HO-1) in SAH rats. Additionally, we found OA could inhibit up-regulation of VEGF and the phosphorylation of p38 mitogen-activated protein kinase (MAPK), and suppress p38MAPK/VEGF/Src signaling pathway which involved in BBB disruption following SAH. From the experimental results, we speculate that OA effectively alleviated SAH-induced vasogenic edema by targeting p38 MAPK/VEGF/Src axis.

NLRP3 inflammasome: A likely target for the treatment of allergic diseases

Allergic diseases, such as asthma, rhinitis, dermatitis, conjunctivitis, and anaphylaxis, have recently become a global public health concern. According to previous studies, the NLRP3 inflammasome is a multi-protein complex known to be associated with many inflammatory conditions. In response to allergens or allergen/damage-associated molecular signals, NLRP3 changes its conformation to allow the assembly of the NLRP3 inflammasome complex and activates caspase-1, which is an evolutionarily conserved enzyme that proteolytically cleaves other proteins, such as the precursors of the inflammatory cytokines IL-1β and IL-18. Subsequently, active caspase-1 cleaves pro-IL-1 and pro-IL-18. Recently, accumulating human and mouse experimental evidence has demonstrated that the NLRP3 inflammasome, IL-1β, and IL-18 are critically involved in the development of allergic diseases. Furthermore, the application of specific NLRP3 inflammasome inhibitors has been demonstrated in animal models. Therefore, these inhibitors may represent potential therapeutic methods for the management of clinical allergic disorders. This review summarizes findings related to the NLRP3 inflammasome and its related factors and concludes that specific NLRP3 inflammasome inhibitors may be potential therapeutic agents for allergic diseases.

Ethnomedicinal, phytochemical and pharmacological profile of a mangrove plant Ceriops Decandra GriffDin Hou

Ceriops decandra is a mangrove tree species, reputed for its folkloric uses in the treatment of gastrointestinal disorders, infection, snakebites, inflammation, and cancer. Different parts of the plant are rich with various phytoconstituents which include diterpenoids (ceriopsin A-G), triterpenoids (lupeol, α-amyrin, oleanolic acid, ursolic acid), and phenolics (catechin, procyanidins).These phytoconstituents and their derivatives could form a new basis for developing new drugs against various diseases. The objective of the present study is to compile the phytochemical, ethnobotanical, biological, and pharmacological significance of the plant to provide directions for future research to find out therapeutically active lead compounds for developing new drugs against diseases of current interest including diabetes, inflammation, and cancer.

Allergic Conjunctivitis-induced Retinal Inflammation Promotes Myopia Progression

Myopia is a highly prevalent eye disease. There is limited information suggesting a relationship between myopia and inflammation. We found children with allergic conjunctivitis (AC) had the highest adjusted odds ratio (1.75, 95% confidence interval [CI], 1.72-1.77) for myopia among the four allergic diseases. A cohort study was conducted and confirmed that children with AC had a higher incidence and subsequent risk of myopia (hazard ratio 2.35, 95%CI 2.29-2.40) compared to those without AC. Lower refractive error and longer axial length were observed in an AC animal model. Myopia progression was enhanced by tumor necrosis factor (TNF)-α or interleukin (IL)-6 administration, two cytokines secreted by mast cell degranulation. The TNF-α or IL-6 weakened the tight junction formed by corneal epithelial (CEP) cells and inflammatory cytokines across the layer of CEP cells, which increased the levels of TNF-α, IL-6, and IL-8 secreted by retinal pigment epithelial cells. The expression levels of TNF-α, IL-6, IL-8, monocyte chemoattractant protein-1, and nuclear factor kappa B were up-regulated in eyes with AC, whereas IL-10 and the inhibitor of kappa B were down-regulated. In conclusion, the experimental findings in mice corroborate the epidemiological data showing that allergic inflammation influences the development of myopia.

Anti-allergic effects of the ethanol extract of Syzygium formosum (Wall.) Masam leaves and its immunoregulatory mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

As documented in a Vietnamese traditional medical encyclopedia, Syzygium formosum (Wall.) Masam leaves have been routinely used among indigenous Vietnamese people for treatment of various allergy-like symptoms including dermatitis and rhinitis.

AIM OF THE STUDY

Anti-allergic activity of S. formosum leaves was examined with a mouse model of chicken ovalbumin (cOVA)-induced food allergy, and mechanisms underlying the anti-allergic effect were explored.

MATERIAL AND METHODS

BALB/c mice were administered i.p. cOVA (20μg) plus alum (2mg) twice on day 0 and 14 for sensitization (immunization). Two weeks after the second immunization, the mice were administered cOVA (50mg) p.o. 5 times every 3 days to induce food allergy symptoms (i.e., anaphylaxis, diarrhea, and drop in the body temperature). Ethanol extract of dried leaves of S. formosum (80mg/kg or 200mg/kg body weight) was administered p.o. daily during the induction (challenge) period.

RESULTS

Treatment with the S. formosum leaves ethanol extract ameliorated the allergic symptoms to a significant extent and in a dose-dependent manner. The treatment also resulted in a significant improvement in the inflammatory lesion in the small intestine and reduction in the numbers of mast cells and eosinophils recruited to the lesion. The treatment also brought about a significant reduction in the levels of Th2 cytokines produced by the mesenteric lymph node cells cultured ex vivo with cOVA. The passive anaphylaxis experiment also showed that the extract treatment impaired the mast cell function.

CONCLUSION

Our study provides a scientific basis for the traditional (indigenous) use of the S. formosum leaves extract for the treatment of various allergy symptoms in Vietnam. In addition, the results show that the extract has activities to suppress antigen-specific Th2 T cell immune responses and the mast cell function, which are directly related with its anti-allergic effect.

Oleanolic Acid and Its Derivatives: Biological Activities and Therapeutic Potential in Chronic Diseases

The increasing demand for natural products as an alternative therapy for chronic diseases has encouraged research into the pharmacological importance of bioactive compounds from plants. Recently, there has been a surge of interest in the therapeutic potential of oleanolic acid (OA) in the prevention and management of chronic diseases. Oleanolic acid is a pentacyclic triterpenoid widely found in plants, including fruits and vegetables with different techniques and chromatography platforms being employed in its extraction and isolation. Several studies have demonstrated the potential therapeutic effects of OA on different diseases and their symptoms. Furthermore, oleanolic acid also serves as a framework for the development of novel semi-synthetic triterpenoids that could prove vital in finding therapeutic modalities for various ailments. There are recent advances in the design and synthesis of chemical derivatives of OA to enhance its solubility, bioavailability and potency. Some of these derivatives have also been therapeutic candidates in a number of clinical trials. This review consolidates and expands on recent reports on the biological effects of oleanolic acid from different plant sources and its synthetic derivatives as well as their mechanisms of action in in vitro and in vivo study models. This review suggests that oleanolic acid and its derivatives are important candidates in the search for alternative therapy in the treatment and management of chronic diseases.

Metabolite Profiling of Eastern Teaberry (Gaultheria procumbens L.) Lipophilic Leaf Extracts with Hyaluronidase and Lipoxygenase Inhibitory Activity

The phytochemical profile and anti-inflammatory activity of Gaultheria procumbens dry lipophilic leaf extracts were evaluated. Forty compounds were identified by GC-MS, representing 86.36% and 81.97% of the petroleum ether (PE) and chloroform (CHE) extracts, respectively, with ursolic acid (28.82%), oleanolic acid (10.11%), methyl benzoate (10.03%), and methyl salicylate (6.88%) dominating in CHE, and methyl benzoate (21.59%), docosane (18.86%), and octacosane (11.72%) prevailing in PE. Three components of CHE were fully identified after flash chromatography isolation and spectroscopic studies as (6S,9R)-vomifoliol (4.35%), 8-demethyl-latifolin (1.13%), and 8-demethylsideroxylin (2.25%). Hyaluronidase and lipoxygenase inhibitory activity was tested for CHE (IC50 = 282.15 ± 10.38 μg/mL and 899.97 ± 31.17 μg/mL, respectively), PE (IC50 = 401.82 ± 16.12 μg/mL and 738.49 ± 15.92 μg/mL), and nine of the main constituents versus heparin (IC50 = 366.24 ± 14.72 μg/mL) and indomethacin (IC50 = 92.60 ± 3.71 μg/mL) as positive controls. With the best activity/concentration relationships, ursolic and oleanolic acids were recommended as analytical markers for the extracts and plant material. Seasonal variation of both markers following foliar development was investigated by UHPLC-PDA. The highest levels of ursolic (5.36-5.87 mg/g DW of the leaves) and oleanolic (1.14-1.26 mg/g DW) acids were observed between August and October, indicating the optimal season for harvesting.

An inhibitor peptide of toll-like receptor 2 shows therapeutic potential for allergic conjunctivitis

Allergic conjunctivitis (AC) is an inflammatory disease of the conjunctiva, which is characterized by antigen challenge and toll-like receptor 2 (TLR2) activation. Here, a designed small peptide ZY12 was found to contain therapeutic potential in staphylococcal enterotoxin B (SEB)-induced AC model. ZY12 treatment showed the remission of clinical signs, plasma total IgE levels, number of mast cells and the proportion of degranulated mast cell in AC mice. Levels of Th2 cytokines (IL-4, IL-5, IL-13) in the lymph nodes or spleen were significantly decreased while those of Th1 cytokine (IFN-γ) were increased in ZY12 treated group, suggesting a protective role of ZY12 in AC by mediating the balance of Th1/Th2 cytokines. Importantly, ZY12 significantly inhibited TLR2 expression in conjunctival tissue. Combined its therapeutic effects with TLR2 inhibitory function, ZY12 might be an ideal candidate for the development of new therapeutic agent for allergic disease.

Possible Mechanism of Action of the Antiallergic Effect of an Aqueous Extract of Heliotropium indicum L. in Ovalbumin-Induced Allergic Conjunctivitis

Heliotropium indicum is used traditionally as a remedy for conjunctivitis in Ghana. This study therefore evaluated the antiallergic potential of an aqueous whole plant extract of Heliotropium indicum (HIE) in ovalbumin-induced allergic conjunctivitis and attempted to predict its mode of action. Clinical scores for allergic conjunctivitis induced by intraperitoneal ovalbumin sensitization (100 : 10 μg OVA/Al(OH)3 in phosphate-buffered saline [PBS]) and topical conjunctival challenge (1.5 mg OVA in 10 μL PBS) in Dunkin-Hartley guinea pigs were estimated after a week's daily treatment with 30-300 mg kg(-1) HIE, 30 mg kg(-1) prednisolone, 10 mg kg(-1) chlorpheniramine, or 10 mL kg(-1) PBS. Ovalbumin-specific IgG and IgE and total IgE in serum were estimated using Enzyme-Linked Immunosorbent Assay. Histopathological assessment of the exenterated conjunctivae was also performed. The 30 and 300 mg kg(-1) HIE treatment resulted in a significantly (p ≤ 0.001) low clinical score of allergic conjunctivitis. Ovalbumin-specific IgG and IgE as well as total serum IgE also decreased significantly (p ≤ 0.01-0.001). The conjunctival tissue in HIE treated guinea pigs had mild mononuclear infiltration compared to the PBS-treated ones, which had intense conjunctival tissue inflammatory infiltration. HIE exhibited antiallergic effect possibly by immunomodulation or immunosuppression.

Oleanolic acid ameliorates dextran sodium sulfate-induced colitis in mice by restoring the balance of Th17/Treg cells and inhibiting NF-κB signaling pathway

In a preliminary experiment, it was found that oleanolic acid (OA), which is widely distributed in food and medicinal plants, inhibited interleukin (IL)-6/tumor growth factor beta-induced differentiation of splenic T cells into Th17 cells. Moreover, OA induced the differentiation of splenic T cells into Treg cells. Therefore, we examined the anti-inflammatory effect of OA in mice with dextran sodium sulfate (DSS)-induced colitis. Oral administration of OA significantly inhibited DSS-induced colon shortening, macroscopic score, and myeloperoxidase activity. Treatment with OA inhibited DSS-induced differentiation to Th17 cells and downregulated the expression of RORγt and IL-17 in the lamina propria of colon and Treg cell differentiation and Foxp3 and IL-10 expression were increased. OA treatment increased the DSS-suppressed expression of tight junction proteins such as ZO-1, occludin, and claudin-1 in the colon. Moreover, OA treatment inhibited DSS-induced expression of tumor necrosis factor-α, interleukin (IL)-1β, and IL-17, the activation of NF-κB and mitogen-activated protein kinases, and increased IL-10 expression. OA also inhibited the activation of NF-κB and expression of proinflammatory cytokines in LPS-stimulated peritoneal macrophages. These findings suggest that OA may ameliorate inflammatory diseases such as colitis by inhibiting Th17 cell differentiation and increasing Treg cell differentiation.

Down-Regulation of miR-146a Expression Induces Allergic Conjunctivitis in Mice by Increasing TSLP Level

Background

Pollen is the most common aeroallergen to cause conjunctivitis. In this study, we established a short ragweed (SRW)-induced mouse model of allergic conjunctivitis (AC) and aimed to explore the potential role of miR-146a and its downstream molecules in the development of ocular allergic inflammation.

Material/Methods

The mouse model of challenge pollen was used for in vivo study. The culture model of primary human limbal epithelium (HLE) exposed to lipopolysaccharide (LPS) was performed for in vitro research. The numbers of eosinophils and total inflammatory cells were examined using Giemsa staining. The expression of mRNA and miR-146a was determined by quantitative RT-PCR, and protein production was evaluated by Western blotting.

Results

In vivo of mice, pollen challenge induced conjunctiva inflammatory response indicated by increased number of eosinophils and total inflammatory cells. Interestingly, pollen significantly attenuated miR-146a expression while it enhanced expression of thymic stromal lymphopoietin (TSLP) and its downstream molecules, including TSLP receptor (TSLPR)/ OX40 ligand (OX40L)/CD11C. In vitro of HCE, downregulation effect of miR-146a expression induced by LPS was reversed by Bay treatment, an inhibitor for nuclear factor kappa B (NF-κB), and LPS-induced cell inflammation is mediated by miR-146a-TSLP/TSLPR/OX40L/CD11C signaling pathway. This was further demonstrated by overexpression of miR-146a in mouse abrogated pollen-triggered conjunctiva inflammatory reaction as well as pollen-induced activity of TSLP/TSLPR/OX40L/CD11C signaling.

Conclusions

Down-regulation of miR-146a expression induces allergic conjunctivitis in mice by increasing TSLP level.