Plasma and urine metabolite profiling reveals the protective effect of Clinacanthus nutans in an ovalbumin-induced anaphylaxis model: ¹H-NMR metabolomics approach

The present study sought to identify the key biomarkers and pathways involved in the induction of allergic sensitization to ovalbumin and to elucidate the potential anti-anaphylaxis property of Clinacanthus nutans (Burm. f.) Lindau water leaf extract, a Southeast Asia herb in an in vivo ovalbumin-induced active systemic anaphylaxis model evaluated by 1H-NMR metabolomics. The results revealed that carbohydrate metabolism (glucose, myo-inositol, galactarate) and lipid metabolism (glycerol, choline, sn-glycero-3-phosphocholine) are the key requisites for the induction of anaphylaxis reaction. Sensitized rats treated with 2000 mg/kg bw C. nutans extract before ovalbumin challenge showed a positive correlation with the normal group and was negatively related to the induced group. Further 1H-NMR analysis in complement with Kyoto Encyclopedia of Genes and Genomes (KEGG) reveals the protective effect of C. nutans extract against ovalbumin-induced anaphylaxis through the down-regulation of lipid metabolism (choline, sn-glycero-3-phosphocholine), carbohydrate and signal transduction system (glucose, myo-inositol, galactarate) and up-regulation of citrate cycle intermediates (citrate, 2-oxoglutarate, succinate), propanoate metabolism (1,2-propanediol), amino acid metabolism (betaine, N,N-dimethylglycine, methylguanidine, valine) and nucleotide metabolism (malonate, allantoin). In summary, this study reports for the first time, C. nutans water extract is a potential anti-anaphylactic agent and 1H-NMR metabolomics is a great alternative analytical tool to explicate the mechanism of action of anaphylaxis

Anti-allergic effect of Clinacanthus nutans aqueous extract: protection against IgE-mediated passive systemic anaphylaxis

Introduction: Anaphylaxis is a serious, rapid and potentially life-threatening allergic response involving IgE or IgG. Clinacanthus nutans, a small native shrub found in tropical Asia possess analgesic, anti-inflammatory and anti-viral activities and traditionally used for skin rashes, insect and snake-bites. In Thailand, alcoholic C. nutans extracts has been used topically for skin rashes, a symptom of allergy. Aim: To justify that C. nutans can treat skin rashes; this study investigated the anti-allergenicity of C. nutans extracts. Methods: Cytotoxicity of C. nutans extracts was evaluated by MTT on RBL-2H3. The most active C. nutans extract was determined by IgE-mediated mast cell degranulation. Acute toxicity of C. nutans aqueous extract was evaluated using female Sprague Dawley rats at 5000 mg/kg. Anti-allergenicity of C. nutans aqueous extract was studied by IgE-mediated passive systemic anaphylaxis (PSA). The release of preformed mediator (β-hexosaminidase) as well as newly synthesized mediators (TNF-α, IL-4 and LTC4) was evaluated. Results: C. nutans extracts were not cytotoxic up to 1 mg/ml (ethanolic) and 6 mg/ml (aqueous). In vitro, C. nutans aqueous extract was able to inhibit the release of preformed mediators but not newly synthesized mediators at 5 mg/ml. The ethanolic extracts were not able to inhibit all mediators tested. At 5000 mg/kg, C. nutans aqueous extract was non-toxic to the rats; no significant difference observed haematologically and biochemically. In vivo, C. nutans aqueous extract did not inhibit mediators of IgE-mediated PSA at 500 mg/kg and 2000 mg/kg. Conclusion: C. nutans aqueous extract was most active but could not inhibit mediators of IgE-mediated PSA. As anaphylaxis could be mediated by IgE orIgG, we postulate that C. nutans aqueous extract may exhibit its anti-allergenicity in IgG-mediated pathway

Identification of Soluble Mediators in IgG-Mediated Anaphylaxis via Fcγ Receptor: A Meta-Analysis

Background: Anaphylaxis is an acute and life-threatening allergic response. Classically and most commonly, it can be mediated by the crosslinking of allergens to immunoglobulin E (IgE)- high affinity IgE receptor (FcεRI) complex found mostly on mast cells. However, there is another pathway of anaphylaxis that is less well-studied. This pathway known as the alternative pathway is mediated by IgG and its Fc gamma receptor (Fcγ). Though it was not documented in human anaphylaxis, a few studies have found that IgG-mediated anaphylaxis can happen as demonstrated in rodent models of anaphylaxis. In these studies, a variety of soluble mediators were being evaluated and they differ from each study which causes confusion in the suitability, and reliability of choice of soluble mediators to be analyzed for diagnosis or therapeutic purposes. Hence, the objective of this meta-analysis is to identify the potential soluble mediators that are involved in an IgG-mediated anaphylaxis reaction.Methods: Studies related to IgG-mediated anaphylaxis were sourced from five search engines namely PubMed, Scopus, Ovid, Cochrane Library, and Center for Agricultural Bioscience International (CABI) regardless of publication year. Relevant studies were then reviewed based on specific inclusion factors. The means and standard deviations of each soluble mediator studied were then extracted using ImageJ or Get Data Graph Digitiser software and the data were subjected to meta-analysis.Results: From our findings, we found that histamine, serotonin, platelet activating factor (PAF), β-hexosaminidase, leukotriene C4 (LTC4), mucosal mast cell protease-1 (MMCP-1), interleukins (IL)-4,−6, and−13; tumor necrosis factor alpha (TNF-α), and macrophage inflammatory protein-1α (MIP-1α) were often being analyzed. Out of these soluble mediators, histamine, PAF, β-hexosaminidase, IL-6, and−13, MIP-1α and TNF-α were more significant with positive effect size and p < 0.001. As study effect was relatively small, we performed publication bias and found that there was publication bias and this could be due to the small sample size studied.Conclusion: As such, we proposed that through meta-analysis, the potential soluble mediators involved in rodent IgG-mediated anaphylaxis to be histamine, PAF, β-hexosaminidase, IL-6 and−13 and MIP-1α, and TNF-α but will require further studies with larger sample size

Hematological, biochemical, histopathological and 1H-NMR metabolomics application in acute toxicity evaluation of clinacanthus nutans water leaf extract

The present study aims for the first time to provide the in vivo acute toxicological profile of the highest dose of Clinacanthus nutans (Burm. f.) Lindau water leaf extract according to the Organization for economic co-operation and development (OECD) 423 guidelines through conventional toxicity and advanced proton nuclear magnetic resonance (1H-NMR) serum and urinary metabolomics evaluation methods. A single dose of 5000 mg/kg bw of C. nutans water extract was administered to Sprague Dawley rats, and they were observed for 14 days. Conventional toxicity evaluation methods (physical observation, body and organ weight, food and water consumption, hematology, biochemical testing and histopathological analysis) suggested no abnormal toxicity signs. Serum 1H-NMR metabolome revealed no significant metabolic difference between untreated and treated groups. Urinary 1H-NMR analysis, on the other hand, revealed alteration in carbohydrate metabolism, energy metabolism and amino acid metabolism in extract-treated rats after 2 h of extract administration, but the metabolic expression collected after 24 h and at Day 5, Day 10 and Day 15 indicated that the extract-treated rats did not accumulate any toxicity biomarkers. Importantly, the outcomes further suggest that single oral administration of up to 5000 mg/kg bw of C. nutans water leaf extract is safe for consumption

Mast cell stabilizing effect of a geranyl acetophenone in dengue virus infection using in vitro model of DENV3-induced RBL-2H3 cells

Mast cells (MCs), a type of immune effector cell, have recently become recognized for their ability to cause vascular leakage during dengue virus (DENV) infection. Although MC stabilizers have been reported to attenuate DENV induced infection in animal studies, there are limited in vitro studies on the use of MC stabilizers against DENV induced MC degranulation. 2,4,6-trihydroxy-3-geranyl acetophenone (tHGA) has been reported to be a potential MC stabilizer by inhibiting IgE-mediated MC activation in both cellular and animal models. The present study aims to establish an in vitro model of DENV3-induced RBL-2H3 cells using ketotifen fumarate as a control drug, as well as to determine the effect of tHGA on the release of MC mediators upon DENV infection. Our results demonstrated that the optimal multiplicities of infection (MOI) were 0.4 × 10-2 and 0.8 × 10-2 focus forming units (FFU)/cell. Ketotifen fumarate was proven to attenuate DENV3-induced RBL-2H3 cells degranulation in this in vitro model. In contrast, tHGA was unable to attenuate the release of both β-hexosaminidase and tumor necrosis factor (TNF)-α. Nonetheless, our study has successfully established an in vitro model of DENV3-induced RBL-2H3 cells, which might be useful for the screening of potential MC stabilizers for anti-dengue therapies

In vitro and in vivo effect of Clinacanthus nutans (Burm. f.) Lindau aqueous extract on IgE and IgG-mediated allergy pathways

Allergy is a hypersensitive reaction against antigens which could be mediated through immunoglobulin (Ig) -E and IgG. About 30 – 40% of people globally are affected with allergy and it is projected to increase due to urbanisation. It has both personal and economic implications thus, requiring urgent attention. Clinacanthus nutans (Burm. f.) Lindau (C. nutans) is commonly found in Malaysia, Thailand and Indonesia. Traditionally used to treat snake and insect bites, skin rashes and others, it was evaluated for its anti-viral, antiinflammatory and anti-cancer properties. Although used to treat skin rashes, its anti-allergy property was not evaluated. Hence, this study evaluated the antiallergy property of C. nutans in in vitro and in vivo allergy models and its underlying mechanism. Meta-analysis was done to identify the commonly analysed soluble mediators in the less established IgG pathway (compared to IgE). The anti-allergy property via IgE pathway of 100% ethanolic, 70% ethanolic-aqueous, 50% ethanolic-aqueous and aqueous C. nutans extracts was assessed through in vitro IgE-induced mast cell degranulation model. The most active extract was then evaluated in IgG-induced macrophage activation model. The underlying mechanism was studied by analysing its effect on the mitogen-activated protein kinase (MAPK) and phosphoinositide-3-kinase (PI3K) pathways’ proteins by Western blotting. The effect was then validated in rodents. Acute toxicity test that analysed the haematological, biochemical and histological profiles was done to determine its safety and safe doses to be used. The overall effect was analysed in ovalbumin-challenged active systemic anaphylaxis (OVA-ASA), whereby both IgE and IgG pathways were activated. The effect of CNAE on specific targeted pathway was analysed in IgE challenged passive systemic anaphylaxis (IgE-PSA) and IgG-PSA models. Soluble mediators were quantified by enzyme-linked immunosorbent assay (ELISA). The commonly studied soluble mediators of IgG pathway identified through meta-analysis were platelet activating factor (PAF), histamine, interleukins (IL)-6, -13 and tumour necrosis factor-α (TNF-α). The most active extract - CNAE significantly reduced histamine and β-hexosaminidase in IgE induced mast cell degranulation model at 5 mg/mL and above. In the IgG induced macrophage activation model, significant decrease of IL-6 and TNF-α were recorded at 1.75 mg/mL and this was due to the inhibition of the phosphorylation of ERK1/2 of the MAPK pathway. From the acute toxicity test, 5000 mg/kg of CNAE (single dose) was not toxic to the animals and the doses - 125, 500 and 2000 mg/kg were chosen for subsequent analyses. In OVA-ASA, CNAE (2000 mg/kg) inhibited IgG (89.5%), PAF (171.1%) and IL-6 (92.6%) but not IgE. There was no significant inhibition of histamine, IL-4 and leukotriene C4 (LTC4) in IgE-PSA even at 2000 mg/kg. However, at 2000 mg/kg, there was 128.2% reduction of PAF and 124.4% reduction of IL-6 in IgG-PSA. Significant reduction of histamine in in vitro IgE-induced mast cell degranulation that was not recorded in IgE-PSA could be due to the overall effect of different cells that were activated in IgE-PSA. In the in vitro model, Rat Basophilic Leukaemic (RBL-2H3) cells which mimicked mast cells were specifically induced while in IgE-PSA, other cells with high-affinity IgE receptor (FcεRI) such as mast cells, eosinophils and basophils were challenged giving an overall effect. In conclusion, the anti-allergy property of C. nutans was potentially in CNAE which targeted the IgG pathway with significant reductions of PAF, IL-6 and TNF-α by inhibiting ERK1/2 pathway. As anaphylaxis is a systemic allergy, the anti-allergy effect of CNAE could be further evaluated on localised models such as atopic eczema or allergic alveolitis

Association of immunoglobulin G abnormalities in diseases: a mini review

Immunoglobulins are antibodies that play important roles in preserving our immune system. They have the ability to initiate humoral responses and remove antigen from the body. Out of the five major isotypes of immunoglobulins, IgG are most abundantly foundin human serum. Abnormalities –deficiency or elevation in the level of IgG are found to be associated to the occurrence of several autoimmune diseases. These may include rheumatoid arthritis, Crohn’s disease, Mikulicz’s disease, Kuttner’s tumour and Hashimoto’s thyroiditis. Apart from autoimmune diseases, IgG has been found to play a role in initiating anaphylaxis, a severe and life threatening form of allergy and lately it has been discovered in cases of dengue virus infection too. It is important to acknowledge the roles of IgG on diseases especially subclass IgG4 which the elevation has been tied to numerous diseases such as Kuttner’s tumour and Hashimoto’s thyroiditis hence termed IgG4-related diseases. In addition, the roles of IgG in anaphylaxis are of importance, too, as IgG has been used in allergy immunotherapy. Hence, this review is a mini compilation of effects of IgG abnormalities based on their subclasses. Hopefully it will provide insightful understanding on the development of diagnostic and therapeutic courses for the aforementioned IgG abnormalities in the future

Ameliorative effect of tocotrienols on perimenopausal-associated osteoporosis—a review

Osteoporosis, or bone loss, is a disease that affects many women globally. As life expectancy increases, the risk of osteoporosis in women also increases, too, and this will create a burden on the healthcare and economic sectors of a country. Osteoporosis was once thought to be a disease that would occur only after menopause. However, many studies have shown that osteoporosis may develop even in the perimenopausal stage. Due to the erratic levels of estrogen and progesterone during the perimenopausal stage, studies suggest that women are exposed to the risk of developing osteoporosis even at this stage. The erratic hormonal changes result in the production of proinflammatory mediators and cause oxidative stress, which leads to the progressive loss of bone-building activities. Tocotrienols, members of vitamin E, have many health-promoting properties. Due to their powerful anti-oxidative and anti-inflammatory properties, tocotrienols have shown positive anti-osteoporotic properties in post-menopausal studies. Hence, we propose here that tocotrienols could also possibly alleviate perimenopausal osteoporosis by discussing in this review the connection between inflammatory mediators produced during perimenopause and the risk of osteoporosis. Tocotrienols could potentially be an anti-osteoporotic agent, but due to their low bioavailability, they have not been as effective as they could be. Several approaches have been evaluated to overcome this issue, as presented in this review. As the anti-osteoporotic effects of tocotrienols were mostly studied in post-menopausal models, we hope that this review could pave the way for more research to be done to evaluate their effect on peri-menopausal models so as to reduce the risk of osteoporosis from an earlier stage

House dust mite allergy in Malaysia: review of research gaps in the current scenario and the way forward

The prevalence of house dust mite (HDM) allergy, especially in Asian countries with rapid urbanization, has been increasing. House dust mites thrive in places with relatively high humidity. With the combination of climate change, naturally high humidity, and urbanization, tropical countries like Malaysia are becoming a hotspot for HDM allergy fast. With a previously reported sensitization rate of between 60 and 80%, it is a worrying trend for Malaysia. However, due to incomplete and out-of-date data, as seen by the limited study coverage in the past, these numbers do not paint a complete picture of the true HDM allergy scene in Malaysia. This review briefly discusses the HDM fauna, the HDM sensitization rate, the common diagnosis and therapeutic tools for HDM allergy in Malaysia, and makes suggestions for possible improvements in the future. This review also highlights the need of more comprehensive population-based prevalence studies to be done in Malaysia, encompassing the three main HDMs—Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Blomia tropicalis—as the lack of up-to-date studies failed to give a clearer picture on the current scenario of HDM allergy in Malaysia. Future studies will be beneficial to the nation in preparing a better blueprint for the management and treatment of HDM allergy

Ameliorative Effect of Tocotrienols on Perimenopausal-Associated Osteoporosis—A Review

Osteoporosis, or bone loss, is a disease that affects many women globally. As life expectancy increases, the risk of osteoporosis in women also increases, too, and this will create a burden on the healthcare and economic sectors of a country. Osteoporosis was once thought to be a disease that would occur only after menopause. However, many studies have shown that osteoporosis may develop even in the perimenopausal stage. Due to the erratic levels of estrogen and progesterone during the perimenopausal stage, studies suggest that women are exposed to the risk of developing osteoporosis even at this stage. The erratic hormonal changes result in the production of proinflammatory mediators and cause oxidative stress, which leads to the progressive loss of bone-building activities. Tocotrienols, members of vitamin E, have many health-promoting properties. Due to their powerful anti-oxidative and anti-inflammatory properties, tocotrienols have shown positive anti-osteoporotic properties in post-menopausal studies. Hence, we propose here that tocotrienols could also possibly alleviate perimenopausal osteoporosis by discussing in this review the connection between inflammatory mediators produced during perimenopause and the risk of osteoporosis. Tocotrienols could potentially be an anti-osteoporotic agent, but due to their low bioavailability, they have not been as effective as they could be. Several approaches have been evaluated to overcome this issue, as presented in this review. As the anti-osteoporotic effects of tocotrienols were mostly studied in post-menopausal models, we hope that this review could pave the way for more research to be done to evaluate their effect on peri-menopausal models so as to reduce the risk of osteoporosis from an earlier stage