Lower Urinary Tract Symptoms (LUTS) as a New Clinical Presentation of Histamine Intolerance: A Prevalence Study of Genetic Diamine Oxidase Deficiency

Lower urinary tract symptoms (LUTS) are highly prevalent, and their treatment is mainly focused on the control of symptoms. Histamine intolerance (HIT) has been related to a variety of systemic symptoms. DAO deficiency has been identified as a significant factor contributing to histamine intolerance (HIT). Preclinical evidence indicates the involvement of histamine in the lower urinary tract. This study aimed to assess the prevalence of diamine oxidase deficiency (DAO) in a prospective cohort of 100 patients with at least moderate LUTS. A genetic study of four single nucleotide polymorphisms (SNPs) (c.-691G>T, c.47C>T, c.995C>T, and c.1990C>G) was performed. HIT was found in 85.9% of patients. The prevalence of at least one minor allele in the SNPs analyzed was 88%, without gender differences. Storage symptoms were more intense in the presence of HIT as well as asthenia and neurological and musculoskeletal symptoms. The presence of minor alleles of the AOC1 gene was associated with a higher intensity of symptoms. Minor alleles from c.-691G>T and c.47C>T SNPs were also associated with a greater severity of obstructive symptoms. Thirty-one percent of patients presented the four SNPS with at least one associated minor allele. The relationship between HIT and LUTS in a mixed population of men and women found in this study supports further investigations to define the pathophysiology of histamine in LUTS.

Exogenous Supplementation with DAO Enzyme in Women with Fibromyalgia: A Double-Blind Placebo-Controlled Clinical Trial

Fibromyalgia (FM) is characterized by chronic musculoskeletal pain, muscle tension, joint mobility loss, and several psychological symptoms severely affecting patient well-being. Histamine is naturally degraded in the small intestine by diamine oxidase (DAO). Hereditary or acquired DAO deficiency causes extracellular histamine accumulation, leading to symptoms similar to those of individuals diagnosed with FM. Thus, this study aimed to assess the efficacy of adding DAO supplementation for 8 weeks to their standard therapy. We randomly assigned 100 women with FM (age: 33-61 years) to the supplementation and control groups. The Fibromyalgia Impact Questionnaire (FIQ), the Pain Catastrophizing Scale (PCS), and intensity scales were applied for a series of clinical symptoms together with the Bristol scale to assess the added value of DAO supplementation. Patients in both groups were receiving complete pharmacological support but some differences in the number of subjects receiving analgesics, antidepressants, and anxiolytics was noted. Patients in both study groups experienced favorable changes during the evaluation period as indicated by their final FIQ and PCS scores, particularly in the DAO group in the latter questionnaire. Qualitatively, the patients assigned to the DAO treatment group had lower scores for fatigue, anxiety, depression, burning and for rumination, magnification, and helplessness.

Evaluation of Serum Diamine Oxidase as a Diagnostic Test for Histamine Intolerance

Histamine intolerance (HIT) is a clinical condition caused by decreased intestinal degradation of ingested histamine, primarily due to reduced enzyme diamine oxidase (DAO) activity, leading to histamine accumulation and causing various clinical manifestations. The measurement of serum DAO is commonly used as the main diagnostic test for HIT, although its diagnostic use is still uncertain. In this retrospective study, we aimed to assess the validity of DAO determination in patients with clinically suspected HIT. We measured DAO levels in 249 patients with suspected HIT and 50 healthy adult controls without HIT-related problems. Based on five clinical criteria, we divided patients into two groups: high (all five inclusion criteria; 41 patients) and low probability of HIT (≤4 inclusion criteria; 208 patients). Patients with a "high probability of HIT" had the lowest DAO (median: 8 U/mL, IQR: 6-10) in comparison to patients with a "low probability of HIT (median: 10 U/mL, IQR: 7-16, p = 0.0006) and healthy controls (median: 18 U/mL, IQR: 14-22, p < 0.0001). The specificity and sensitivity for DAO levels < 3/< 10 U/mL (manufacturer's set cut-off) to discriminate between patients with ''high probability of HIT'' and healthy controls were 100%/92% and 2%/71%. On the other hand, the specificity and sensitivity to discriminate between patients with ''high probability of HIT'' and ''low probability of HIT'' were 97%/61% and 2%/71%, respectively. Serum DAO determination represents an additional asset to the diagnosis of HIT based on clinical evaluation and assessment, but the diagnosis should not solely rely on DAO measurements.

Effects of Diets Based on Hydrolyzed Chicken Liver and Different Protein Concentrations on the Formation and Deamination of Biogenic Amines and Total Antioxidant Capacity of Dogs

Biogenic amines are synthesized through the bacterial decarboxylation of amino acids, commonly found in high levels in animal by-product meals due to spoilage. Furthermore, biogenic amines and other metabolites can be produced by the fermentation of proteins in the hindgut according to the protein source and concentration of crude protein (CP) in the diet. Thus, this study aimed to evaluate two protein sources (poultry by-product meal (PBPM) and hydrolyzed chicken liver powder (HCLP)) and three CP concentrations (24, 32, and 40%) and their effects on the consumption and fecal excretion of biogenic amines, plasma monoamine oxidase (MAO) and diamine oxidase (DAO) activities, and total antioxidant capacity (TAC) of healthy adult dogs after 30 days of feeding the experimental diets. Twelve dogs were randomly distributed into six treatments (n = 6/treatment): PBPM24 (PBPM with 24% CP); PBPM32 (PBPM with 32% CP); PBPM40 (PBPM with 40% CP); HCLP24 (HCLP with 24% CP); HCLP32 (HCLP with 32% CP); HCLP40 (HCLP with 40% CP). The PBPM and PBPM-based diets had higher concentrations of putrescine, cadaverine, tyramine, histamine, agmatine, and total biogenic amines. In contrast, HCLP and HCLP-based diets contained higher concentrations of spermidine, phenylethylamine, and spermine. The PBPM and PBPM-diets had higher biogenic amine index (BAI) indicating lower quality due to the high content of putrescine, cadaverine and tyramine. Dogs fed diets with PBPM and higher protein concentrations consumed more putrescine, cadaverine, tyramine, agmatine, and total amines (p < 0.0001), while dogs fed with HCLP consumed more spermidine, phenylethylamine, and spermine (p < 0.0001). Fecal excretion of phenylethylamine was greater in dogs fed HCLP32 and HCLP40 diets (p = 0.045). Dogs fed with HCLP tended to excrete more spermidine and tryptamine via feces, while higher protein concentrations tended to increase fecal excretion of cadaverine (p < 0.10). Plasma MAO activity was higher in dogs fed HCLP24 and PBPM32 diets (p = 0.024). The plasma activities of DAO and TAC were not different between diets (p > 0.05). Although we did not evaluate the intestinal activities of MAO and DAO, our results suggest that healthy adult dogs have an efficient deamination process on the gut epithelium.

The Use of DAO as a Marker for Histamine Intolerance: Measurements and Determinants in a Large Random Population-Based Survey

Histamine intolerance (HIT) is a common adverse reaction to food where elimination and reintroduction of histamine-rich food is part of the investigation. Analysis of the enzyme diamine oxidase (DAO) is sometimes used as an additional tool for diagnosis. This study aimed to describe the distribution of DAO in a large representative cohort of adults and to determine the association between DAO activity and possible associated factors. The study is based on the population-based West Sweden Asthma Study and includes 1051 subjects. Subjects underwent structured interviews including questions on demography, asthma, allergy symptoms, and lifestyle factors. Subjects were assessed for specific-IgE-antibodies and measurement of DAO activity in serum. Previously suggested cut-off levels for low values (<3 U/mL), normal values (>10 U/mL), and median levels of DAO were used. In the group of 1051 subjects, only a few presented reactions upon histamine intake, whereas 44% presented DAO levels below the suggested normal cut-off levels. BMI and age were shown to have an impact on DAO activity among women with increasing activity of DAO with increasing BMI and age. Among men, only increasing age was seen to have an impact on DAO levels. There was no difference in DAO levels with different sensitization status to common foods or airborne allergens. No association between DAO levels and reported symptoms to histamine-rich foods could be found. In conclusion, the determination of the DAO enzyme needs to be re-evaluated and may not be used as a valuable tool for histamine intolerance using current cut-off values. Further studies are needed to improve the use of DAO as a biomarker for histamine intolerance.

Yinlai Decoction Protects Microstructure of Colon and Regulates Serum Level of D-Lactic Acid in Pneumonia Mice Fed with High-Calorie and High-Protein Diet

OBJECTIVE

To investigate the effect of Yinlai Decoction (YD) on the microstructure of colon, and activity of D-lactic acid (DLA) and diamine oxidase (DAO) in serum of pneumonia mice model fed with high-calorie and high-protein diet (HCD).

METHODS

Sixty male Kunming mice were randomly divided into 6 groups by the random number table method: normal control, pneumonia, HCD, HCD with pneumonia (HCD-P), YD (229.2 mg/mL), and dexamethasone (15.63 mg/mL) groups, with 10 in each group. HCD mice were fed with 52% milk solution by gavage. Pneumonia mice was modeled with lipopolysaccharide inhalation and was fed by gavage with either the corresponding therapeutic drugs or saline water, twice daily, for 3 days. After hematoxylin-eosin staining, the changes in the colon structure were observed under light microscopy and transmission electron microscope, respectively. Enzyme-linked immunosorbent assay was used to detect the protein levels of DLA and DAO in the serum of mice.

RESULTS

The colonic mucosal structure and ultrastructure of mice in the normal control group were clear and intact. The colonic mucosal goblet cells in the pneumonia group tended to increase, and the size of the microvilli varied. In the HCD-P group, the mucosal goblet cells showed a marked increase in size with increased secretory activity. Loose mucosal epithelial connections were also observed, as shown by widened intercellular gaps with short sparse microvilli. These pathological changes of intestinal mucosa were significantly reduced in mouse models with YD treatment, while there was no significant improvement after dexamethasone treatment. The serum DLA level was significantly higher in the pneumonia, HCD, and HCD-P groups as compared with the normal control group (P<0.05). Serum DLA was significantly lower in the YD group than HCD-P group (P<0.05). Moreover, serum DLA level significantly increased in the dexamethasone group as compared with the YD group (P<0.01). There was no statistical significance in the serum level of DAO among groups (P>0.05).

CONCLUSIONS

YD can protect function of intestinal mucosa by improving the tissue morphology of intestinal mucosa and maintaining integrity of cell connections and microvilli structure, thereby reducing permeability of intestinal mucosa to regulate the serum levels of DLA in mice.

Cumulative effect of AOC1 gene variants on symptoms and pathological conditions in adult women with fibromyalgia: a pilot study

Introduction: The amine oxidase copper-containing 1 (AOC1) gene encodes for the diamine oxidase (DAO) enzyme. DAO is an enzyme that catabolizes some molecules, including histamine, and is the degradative enzyme in the polyamine catabolic pathway that is active in intestinal mucosal cells. Variants of AOC1 are associated with reduced DAO activity, resulting in accumulation of high levels of histamine and causing a wide range of neurological, gastrointestinal, and epidermal disorders, which are present in people with fibromyalgia. This study aimed to evaluate the impact of four AOC1 gene variants, namely, rs10156191, rs1049742, rs1049793, and rs2052129, on fibromyalgia symptoms measured by the Fibromyalgia Impact Questionnaire (FIQ), such as sleep disorders, atopic dermatitis, migraine, gastrointestinal (GI) disorders, allergies, and intolerances, in adult women with fibromyalgia. Methods: The sample consisted of 100 unrelated women with fibromyalgia between 33 and 60 years of age (48.48 years ±7.35), whose were diagnosed by a rheumatologist based on symptoms such as pain, stiffness, and fatigue. Single-nucleotide polymorphisms (SNPs) of AOC1 were identified using oral mucosa samples collected following a standard hygiene protocol. DNA was extracted, and gene variants of interest were analyzed using multiplex single-nucleotide primer extension (SNPE). Clinical data were collected using the FIQ and a series of variables that quantified the intensity and frequency of the symptoms. Results: The minor allele frequencies of rs10156191, rs1049742, rs1049793, and rs2052129 were 31.5, 10, 32.5, and 27%, respectively. Each variant was found to be in Hardy-Weinberg equilibrium, but partial linkage disequilibrium between AOC1 SNPs is suspected. The results show that fibromyalgia symptoms measured using the FIQ tend to increase with the number of risk alleles and that the intensity of dry skin and low stool consistency may be associated with an increase in the number of these alleles. Conclusion: This study constitutes the first step in investigating associations between fibromyalgia symptoms and candidate variants of the AOC1 gene in DAO enzyme activity. Identification of reduced DAO activity may improve the quality of life and treatment of symptoms in fibromyalgia patients.

Is DAO in serum affected by food challenge with a histamine-rich meal?

This case study examines the kinetics of the diamine oxidase levels after challenge with a histamine-rich meal in patients with histamine intolerance as an alternative diagnostic tool to conventional tests combined with the dietary intervention.

Changes in serum concentration and activity of diamine oxidase during the first month of life in calves

The serum concentration and activity of diamine oxidase (DAO) in calves with or without diarrhea during the first month of life were examined. The serum DAO concentration was highest on day 0 after birth, and gradually decreased. No differences in serum DAO concentrations were observed between calves with diarrhea and control calves. In contrast, serum DAO activity was lowest on day 0 after birth, and gradually increased. Serum DAO activity in calves with diarrhea was lower than that in the control calves from day 20 after birth. These findings suggest that serum DAO activity and concentration are not correlated, and serum DAO activity is useful for assessing damage to the small intestinal mucosa in calves.

β-N-Methylamino-L-Alanine (BMAA) Modulates the Sympathetic Regulation and Homeostasis of Polyamines

The neurotoxin β-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid produced by cyanobacteria. Non-neuronal toxicity of BMAA is poorly studied with a reported increase in reactive oxygen species and a decrease in the antioxidant capacity of liver, kidney, and colorectal adenocarcinoma cells. The aim of this research is to study the toxicity of BMAA (0.1-1 mM) on mitochondria and submitochondrial particles with ATPase activity, on the semicarbazide-sensitive amino oxidases (SSAOs) activity of rat liver, and on an in vitro model containing functionally active excitable tissues-regularly contracting heart muscle preparation with a preserved autonomic innervation. For the first time the BMAA-dependent inhibition of SSAO activity, the elimination of the positive inotropic effect of adrenergic innervation, and the direct and reversible inhibition of adrenaline signaling in ventricular myocytes with 1 mM BMAA were observed. Additionally, it is confirmed that 1 mM BMAA can activate mitochondrial ATPase indirectly. It is concluded that a higher dose of BMAA may influence multiple physiological and pathological processes as it slows down the degradation of biogenic amines, downregulates the sympathetic neuromediation, and embarrasses the cell signaling of adrenergic receptors.

Azospirillum baldaniorum Sp 245 inoculation affects cell wall and polyamines metabolisms in cucumber seedling roots

Azospirillum baldaniorum Sp 245 is a model plant growth-promoting rhizobacterium. The first cross-talk with plants takes place within the roots. Roots cells growth is constrained by the primary cell wall (CW). Also, neighboring CW form the apoplast that should affect cells signaling and biochemical messages. Studies on CW phenolic composition ferulate (FA), diferulates (DFA) and p-coumarate and polyamines (PA) metabolisms of A. baldaniorum Sp 245- inoculated roots and on bacterial PA production in culture media should help to understand more about the mechanisms involved in Azospirillum-root association. For this purpose, CW-bound FA, DFA and p-coumarate contents, putrescine (put) and spermidine contents, diamine and polyamine oxidases activities, and H2O2 content of Cucumis sativus roots from dark grown seedlings inoculated with A. baldaniorum Sp 245 were determined. Also, bacterial PA production under constant agitation or static conditions was evaluated. Results showed lesser contents of all phenolics, and higher FA/DFA ratio in CW of inoculated roots that should be responsible for roots growth promotion. Also, the increased put content, DAO activity, and H2O2 production in the roots should be associated to A. baldaniorum Sp 245 growth promotion in early stages. Finally, the participation of both PA in A. baldaniorum Sp 245 biofilm formation was demonstrated.

Diamine Oxidase Activity Deficit and Idiopathic Rhinitis: A New Subgroup of Non-Allergic Rhinitis?

Idiopathic rhinitis represents more than 50% of non-allergic rhinitis, a heterogeneous group that involves the symptomatic inflammation of the nasal mucosa. The TRPV1 receptor of unmyelinated C-type neurons appears to be involved in its pathophysiology. Histamine, whose main catabolic enzyme is DAO, is one of the mediators that can activate this receptor. The failure of DAO causes an increase in the level of histamine in the body and, consequently, the activation of TRPV1. The objective was to investigate the existence of a DAO enzyme activity deficit in idiopathic rhinitis and its correlation with symptoms. A cross-sectional study was conducted in 116 idiopathic rhinitis patients, and DAO activity, nasal peak inspiratory flow, and rhinitis severity were recorded. The prevalence of a DAO activity deficit was 41.38% (95%CI 0.33−0.50; p = 0.05). The DAO activity in patients with mild rhinitis was 52.93 ± 8.72 HDU/mL, in those with moderate rhinitis it was 120.33 ± 71.63 HDU/mL, and in those with severe rhinitis it was 92.58 ± 27.75 HDU/mL (p = 0.006). The NPIF in patients with a DAO activity deficit was 107.92 ± 34.05 L/min, compared to 72.35 ± 27.16 L/min in patients with normal enzymatic activity (p < 0.001), demonstrating a linear correlation between activity levels and nasal obstruction (−0.45; p < 0.001). Therefore, patients with a DAO deficiency and idiopathic rhinitis could present a milder disease course, because the repeated and continuous activation of TRPV1 led to a partial or total decrease in their response (desensitization). This new theory represents a different perspective for the study of idiopathic rhinitis and its relationship with TRPV1, with the regulation or modulation of the desensitization of TRPV1 being an important therapeutic target for patients with idiopathic rhinitis in the future.

Enhancement of γ-aminobutyric acid content in shells of passion fruit (Passiflora edulis) under anoxic vacuum conditions

Passiflora edulis, commonly known as passion fruit, is a popular all-weather fruit eaten fresh or processed. Its shells, which currently are mostly discarded as waste and hurt the environment, account for more than half of the passion fruit. The shells contain gamma-aminobutyric acid (GABA) which is the main inhibitory neurotransmitter and has many proven medical values such as antidepressant, anti-anxiety, etc. Many studies have shown that GABA production in plants can be significantly increased by reverse stress. Taking Tainong 1 as a typical passion fruit cultivar, this study explored the optimal anoxic vacuum treatment for increasing the GABA content of passion fruit shells. The content increased to 2139.25 ± 26.69 mg/100 g on day 4 of chill storage after vacuum packing (63.68% higher than the control). The activities of glutamate decarboxylase (GAD) and diamine oxidase (DAO) were significantly higher in the vacuum-treated group than in the control group after 4 days of vacuum-chill storage. On day 5 of vacuum-chill storage, the activities of all measured enzymes decreased except for the increase of GABA transaminase (GABA-T), which was accompanied by a decrease in GABA content. Vacuum treatment and subsequent chill storage increased the content of GABA, thereby increasing functional value of passion fruit shells.

Alterations of gut microbiota and cytokines in elevated serum diamine oxidase disorder

The present study aimed to explore gut microbiota alterations and host cytokine responses in a population with elevated serum diamine oxidase (DAO) disorder. A total of 53 study participants were included in this study, segregated into 2 groups: subjects with high-level DAO (DAO-H, n = 22) subjects with normal DAO level (DAO-N, n = 31). We investigated the clinical and demographic parameters of study participants. The fecal bacterial communities and serum cytokines in 2 groups were assessed by 16S ribosomal RNA gene sequencing and immunoassay. High-pressure liquid chromatography was used to determine hemoglobin Alc. Flow cytometry was used to find the cytokine level in the blood serum. There is no difference in age, total cholesterol (TCHO), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), hemoglobin Alc, fasting plasma glucose (FPG) and homocysteine between the 2 groups. No significant difference were found in α-diversity between the 2 groups, however, the gut microbiota of subjects in DAO-H were characterized by marked interindividual differences, decreased abundance of Phocaeicola, Lachnospira, Bacteroides, Alistipes, Agathobacter, Lachnospira and Bactetoides and increased abundances of Mediterraneibacter, Blautia, Faecallibacterium, Agathobacter, and Parasutterella. Furthermore, the cytokines were no related to the DAO level in both groups and exhibited no significant differences between DAO-H and DAO-N. This study adds a new dimension to our understanding of the DAO and gut microbiota, and revealed that an increase in the DAO level in the intestinal mucosa could alter the gut microbiota composition, which can cause gut-related complications. Research is needed to extensively evaluate downstream pathways and provide possible protective or treatment measures pertaining to relevant disorders.

Intestinal Permeability Associated with the Loss of Skeletal Muscle Strength in Middle-Aged and Older Adults in Rural Area of Beijing, China

The association between intestinal permeability and sarcopenia remains unclear, and few studies have mentioned the relationship between intestinal permeability and skeletal muscle strength. The present cross-sectional community study was conducted in a rural area of Beijing to explore the association between intestinal permeability and handgrip strength (HGS) in middle-aged and older adults. Serum lipopolysaccharide (LPS), diamine oxidase (DAO) and D-lactate were detected to evaluate intestinal permeability. Gut microbiota (GM) and its potential interaction were also analyzed in the decision tree model. HGS was negatively correlated with DAO (r = −0.396, p < 0.01) in males. The negative association between HGS and DAO remained significant with the adjustment of covariates (β = −1.401, p < 0.05). Serum DAO and LPS were both negatively associated with HGS in middle-aged and older males, with the significant interactions of GM in the decision tree model, and D-lactate showed a negative association with HGS in females. Therefore, intestinal permeability was associated with the loss of skeletal muscle strength in middle-aged and older adults, and serum DAO may be a novel predictor for the loss of skeletal muscle strength in middle-aged and older males.

Increased serum diamine oxidase activity in nonallergic patients with migraine

BACKGROUND/OBJECTIVES

Histamine has shown a possible role in the etiopathogenesis of migraine. It has been reported an association between some polymorphisms in the diamine oxidase (DAO) gene and migraine, especially in women. Two studies addressing DAO activity in migraine patients showed conflicting results. We investigated the possible relationship of serum DAO activity and histamine levels and 3 polymorphisms in the DAO gene with the risk for migraine.

METHODS

We studied the frequencies of DAO rs10156191, rs1049742 and rs1049793 genotypes and allelic variants in 298 migraine patients and 360 healthy controls (using a TaqMan-based qPCR assay), and serum DAO activity and histamine levels in a subset of 99 migraine patients and 115 controls with strict exclusion criteria, and analysed the relationship of these variables with several clinical features of migraine.

RESULTS

The frequencies of the DAO genotypes and allelic variants analysed were similar in migraine patients and controls. Serum DAO activity was significantly higher in migraine patients (Vmax/Km 4.24 ± 2.93 vs. 3.60 ± 7.64, p < 0.001), especially in females (Vmax/Km 4.63 ± 2.96 vs. 3.18 ± 2.32, p < 0.0001), while serum histamine was similar in both study groups.

CONCLUSION

Serum DAO activity was increased in patients with migraine, especially in females, while serum histamine levels were normal. None of the studied polymorphisms was associated with the risk for migraine.

Serum Diamine Oxidase Values, Indicating Histamine Intolerance, Influence Lactose Tolerance Breath Test Results

Lactose intolerance (LIT) is one of the major causes of irritable bowel syndrome (IBS) spectrum complaints. Differences in inadequate lactose digestion are described as various LIT phenotypes with basically unknown pathophysiology. In LIT patients, we retrospectively assessed the effect of histamine intolerance (HIT) on expiratory hydrogen (H2) during H2 lactose breath tests. In a retrospective evaluation of charts from 402 LIT patients, 200 patients were identified as having only LIT. The other 202 LIT patients were found to additionally have diamine oxidase (DAO) values of <10 U/mL, which indicates histamine intolerance (HIT). To identify HIT, standardized questionnaires, low serum DAO values and responses to a histamine-reduced diet were used. Patients were separated into three diagnostic groups according to the result of H2 breath tests: (1) LIT, with an H2 increase of >20 parts per million (ppm), but a blood glucose (BG) increase of >20 mg/dL, (2) LIT with an H2 increase of 20 ppm in combination with a BG increase of <20 mg/dL, and (3) LIT with an exhaled H2 increase of <20 ppm and BG increase of <20 mg/dL. Pairwise comparison with the Kruskal Wallis test was used to compare the areas under the curve (AUC) of LIT and LIT with HIT patients. Exhaled H2 values were significantly higher in H2 > 20 ppm and BG < 20 mg/dL patients with LIT and HIT (p = 0.007). This diagnostic group also showed a significant higher number of patients (p = 0.012) and a significant higher number of patients with gastrointestinal (GI) symptoms during H2 breath tests (p < 0.001). Therefore, low serum DAO values, indicating HIT, influence results of lactose tolerance breath tests.

Basal Serum Diamine Oxidase Levels as a Biomarker of Histamine Intolerance: A Retrospective Cohort Study

Background: Histamine Intolerance (HIT) is a multifaceted pseudoallergic disorder possibly due to defective histamine metabolism. Diamine oxidase (DAO) contributes to histamine degradation and can be measured in the serum. The role of DAO measurement in the diagnostic work-up of HIT still remains unclear, and conflicting results have been reported in the literature. Therefore, we aimed to evaluate the possible clinical usefulness and consistency of DAO value ranges as provided by the assay manufacturer and verify whether they could predict the response to treatment. Methods: We retrospectively analyzed 192 outpatients with HIT symptoms and measured serum DAO values at baseline. Patients were prescribed either with low-histamine diet and/or enzymatic supplementation according to symptom severity and re-evaluated six to eight months later. Patients were stratified into three groups according to DAO levels: <3 U/mL, 3−10 U/mL, and >10 U/mL. HIT severity was assessed on a scale of 1 to 5 before and after treatment. Results: A total of 146 patients completed the study. Gastrointestinal and cutaneous symptoms, often associated with headache, were more frequent in subjects with DAO < 10 U/mL. Symptom severity and DAO ranges were correlated. Patients with intermediate DAO levels (3−10 U/mL) showed a more complex clinical phenotype but also a more significant improvement in symptom severity (score reduction 50%, interquartile range (IQR) = 33−60%) when compared to patients with low DAO (40%, IQR = 20−60%; p = 0.045) or high DAO (33%, IQR = 0−50%; p < 0.001). Complex clinical phenotypes were also more frequent in patients with intermediate DAO levels. Conclusions: HIT is characterized by typical symptoms and low levels of DAO activity. Symptom severity was associated with the degree of DAO deficiency. Patients with DAO values between 3 and 10 U/mL show the best response to treatment (low-histamine diet and/or DAO supplementation). DAO value could arguably be considered as a predictor of clinical response to treatment. Prospective studies are needed to confirm these data.

Helicobacter pylori infection and lactose intolerance increase expiratory hydrogen

Infection with Helicobacter pylori (H.pylori) may cause dyspepsia and/or unexplained functional nonspecific, gastrointestinal complaints of the irritable bowel syndrome (IBS) spectrum. Hitherto, in H. pylori infected patients with symptoms of the IBS spectrum the occurrence of additional food intolerance/malabsorption is not evaluated. We used a retrospective analysis of charts from 548 patients who presented with gastrointestinal complaints of the irritable bowel syndrome spectrum. An enzyme-linked IgA immunosorbent assay or histologic evaluation of gastric mucosa were used to detect H. pylori infection. A hydrogen breath (H₂) test was performed to evaluate fructose malabsorption (FM) and lactose intolerance (LIT). Serum diamine oxidase value of <10 U/ml and a response to a histamine-reduced diet was used to identify histamine intolerance (HIT). We found 293 patients infected with H. pylori, within these were 58 H. pylori patients with LIT, 23 H. pylori LIT patients with FM and 46 H. pylori LIT patients with HIT. Additionally, 13 H. pylori, lactose- and histamine intolerance patients also had FM. The Kruskal Wallis test and pairwise comparison were used to analyze differences of the area under the curve of expiratory hydrogen. In lactose H₂ breath tests compared with LIT-only patients, LIT with H. pylori, LIT and H. pylori with HIT, LIT and H. pylori with FM showed significantly higher exhaled H₂ levels (p=0.022). Pairwise comparison demonstrated H. pylori infected patients with LIT exhaled more H₂ compared to LIT-only (p=0.029). H. pylori with lactose- and histamine intolerance, and H. pylori with lactose-, histamine intolerance and FM compared to H. pylori-only patients indicated a significantly higher occurrence of stomach pain during lactose H₂ breath tests (p=0.012 and p=0.005, respectively). We demonstrate that LIT patients with high expiratory H₂ levels in lactose breath tests may have H. pylori infection and possibly additional food intolerance/malabsorption. Subsequently, besides H. pylori eradication, a dietician is necessary for an individually tailored reduction- or exclusion diet of symptom triggering food components.

Prospective Randomized Trial of Early Postoperative Enteral and Total Parenteral Nutrition for Treating Esophageal Cancer

BACKGROUND/AIM

Surgical stress significantly decreases serum diamine oxidase (DAO), a marker of intestinal mucosal maturation and integrity. This study aimed to determine the effects of postoperative enteral and total parenteral nutrition (EN and TPN, respectively) in patients with esophageal cancer.

PATIENTS AND METHODS

This prospective randomized trial compared serum DAO activities, nutritional states, trace elements and complications between patients who underwent esophagectomy and received EN or TPN for seven days thereafter.

RESULTS

Fifty-one patients were randomized to receive EN or TPN. The rates of change in serum DAO activity from the day before surgery were 0.79, 0.89 and 0.91 on postoperative days (POD) 1, 3 and 7, respectively, in the EN group, and 0.64, 0.76 and 1.06, respectively, in the TPN group, with no significant differences. Furthermore, the rates of changes in indicators of nutritional status, namely total protein, albumin, total cholesterol, trace element concentrations and infectious and non-infectious complications did not significantly differ between the groups.

CONCLUSION

EN and/or TPN can be administered for early nutritional management until resumption of oral intake after esophagectomy according to the postoperative status of individual patients with esophageal cancer.

Guideline on management of suspected adverse reactions to ingested histamine: Guideline of the German Society for Allergology and Clinical Immunology (DGAKI), the Society for Pediatric Allergology and Environmental Medicine (GPA), the Medical Association of German Allergologists (AeDA) as well as the Swiss Society for Allergology and Immunology (SGAI) and the Austrian Society for Allergology and Immunology (ÖGAI)

Adverse reactions to food or food ingredients are more often perceived than objectively verifiable. However, reliable laboratory tests are often lacking. As a result, people with perceived adverse reactions to food often follow extensive elimination diets for years and unnecessarily restrict their diet, as in the case of the frequently suspected histamine intolerance. In this condition, laboratory parameters such as the determination of diamine oxidase in serum have been shown to be inconclusive. The lack of symptom reproducibility calls into question the clinical picture of adverse reactions to ingested histamine. In order to approach persons with perceived histamine intolerance and to support them in moving from blanket restrictions, which are often unnecessarily strict, to effective personalized therapeutic strategies, the present guideline of the Working Group on Food Allergy of the German Society of Allergology and Clinical Immunology (DGAKI) in cooperation with the Medical Association of German Allergists (AeDA), the Pediatric Allergology and Environmental Medicine (GPA) as well as the Swiss Society of Allergology and Immunology (SGAI) and the Austrian Society of Allergology and Immunology (ÖGAI) recommends a practicable diagnostic and therapeutic approach.

Heparin-binding motif mutations of human diamine oxidase allow the development of a first-in-class histamine-degrading biopharmaceutical

Background

Excessive plasma histamine concentrations cause symptoms in mast cell activation syndrome, mastocytosis, or anaphylaxis. Anti-histamines are often insufficiently efficacious. Human diamine oxidase (hDAO) can rapidly degrade histamine and therefore represents a promising new treatment strategy for conditions with pathological histamine concentrations.

Methods

Positively charged amino acids of the heparin-binding motif of hDAO were replaced with polar serine or threonine residues. Binding to heparin and heparan sulfate, cellular internalization and clearance in rodents were examined.

Results

Recombinant hDAO is rapidly cleared from the circulation in rats and mice. After mutation of the heparin-binding motif, binding to heparin and heparan sulfate was strongly reduced. The double mutant rhDAO-R568S/R571T showed minimal cellular uptake. The short α-distribution half-life of the wildtype protein was eliminated, and the clearance was significantly reduced in rodents.

Conclusions

The successful decrease in plasma clearance of rhDAO by mutations of the heparin-binding motif with unchanged histamine-degrading activity represents the first step towards the development of rhDAO as a first-in-class biopharmaceutical to effectively treat diseases characterized by excessive histamine concentrations in plasma and tissues.

Funding

Austrian Science Fund (FWF) Hertha Firnberg program grant T1135 (EG); Sigrid Juselius Foundation, Medicinska Understödsförening Liv och Hälsa rft (TAS and SeV).

A Pilot Study Evaluating the Effectiveness and Safety of Daikenchuto (TJ-100) for the Treatment of Postoperative Abdominal Pain or Bloating in Patients Undergoing Hepatectomy: Study Protocol for a Randomized, Open, Controlled Trial

This study is being performed to evaluate the effectiveness and safety of TJ-100 TSUMURA Daikenchuto (DKT) Extract Granules in preventing post-hepatectomy digestive symptoms, and to examine the effects of DKT on small intestinal mucosal atrophy using diamine oxidase (DAO) and glucagon-like peptide-2 (GLP-2) activities. This is a randomized, open, controlled trial using patients treated with usual care as the control group. Patients who meet the inclusion criteria are randomized to the study groups. Eligible patients are randomized to the DKT therapy group (DKT administration for 14 days postoperatively or until the day of discharge if a patient leaves the hospital less than 14 days after the surgery) or the usual care group (no administration of DKT (ratio 1:1). Using the NRS (numeric rating scale) as an indicator, we will attempt to show whether DKT is effective for abdominal pain and bloating after surgery by comparing both groups. We will also attempt to evaluate postoperative small intestinal mucosal atrophy using DAO and GLP-2 activities in the serum, and postoperative nutrient absorption using nutrient assessment indicators. This study is being conducted according to the CONSORT statement. A consent form was signed by all participants, and the study protocol has been approved by the Central Review Board and Local Ethics Committee (CRB7180001).

Targeted inhibition of allergen-induced histamine production by neutrophils

Histamine is a critical inflammatory mediator in allergic diseases. We showed in a previous work that neutrophils from allergic patients produce histamine in response to allergens to which the patients were sensitized. Here, we investigate the molecular mechanisms involved in this process using peripheral blood neutrophils. We challenged these cells in vitro with allergens and analyzed histamine release in the culture supernatants. We also explored the effect of common therapeutic drugs that ameliorate allergic symptoms, as well as allergen-specific immunotherapy. Additionally, we examined the expression of histidine decarboxylase and diamine oxidase, critical enzymes in the metabolism of histamine, under allergen challenge. We show that allergen-induced histamine release is dependent on the activation of the phosphoinositide 3-kinase, mitogen-activated protein kinase p38, and extracellular signal-regulated kinase 1/2 signaling pathways. We also found a contribution of the phosphatase calcineurin to lesser extent. Anti-histamines, glucocorticoids, anti-M3-muscarinic receptor antagonists, and mainly β₂ -receptor agonists abolished the allergen-dependent histamine release. Interestingly, allergen-specific immunotherapy canceled the histamine release through the downregulation of histidine decarboxylase expression. Our observations describe novel molecular mechanisms involved in the allergen-dependent histamine release by human neutrophils and provide new targets to inhibit histamine production.

Human diamine oxidase is readily released from activated neutrophils ex vivo and in vivo but is rarely elevated in bacteremic patients

During human diamine oxidase (DAO) ELISA development we noticed that in serum DAO concentrations appear to be higher when compared to plasma. Neutrophils contain DAO in the specific granules and we hypothesized that DAO is released from neutrophils during serum coagulation. If activation of neutrophils can release DAO, its concentrations might be elevated in vivo after lipopolysaccharide (LPS) administration and in bacteremic patients. Using blood from healthy volunteers DAO concentrations were measured ex vivo in serum, citrate, EDTA and heparin plasma over several hours and after activation of neutrophils. Lipopolysaccharide and granulocyte-colony stimulating factor (G-CSF) were administered to 15 and 8 healthy volunteers, respectively and DAO concentrations were measured at different timepoints. DAO antigen levels were also determined in three different subcohorts of patients with culture-proven bacteremia and high C-reactive protein (CRP) levels. DAO concentrations were elevated in a time-dependent manner in serum but not in EDTA or citrate plasma (P < 0.01). Neutrophil activation using phorbol myristate acetate (PMA) and zymosan dose-dependently caused DAO concentrations to be elevated more than 10-fold at both 22°C and 37°C (both P-values <0.001). Administration of LPS to healthy volunteers released DAO from neutrophils (P < 0.001). Of the 55 different bacteremic patients selected from three independent cohorts only 3 (5.4%) showed highly elevated DAO concentrations. Serum DAO concentrations do not accurately reflect circulating enzyme levels but coagulation-induced neutrophil activation and consequently DAO release. Only a few bacteremic patients show high DAO concentrations able to degrade histamine rapidly.

Histamine Intolerance-The More We Know the Less We Know. A Review

The intake of food may be an initiator of adverse reactions. Food intolerance is an abnormal non-immunological response of the organism to the ingestion of food or its components in a dosage normally tolerated. Despite the fact that food intolerance is spread throughout the world, its diagnosing is still difficult. Histamine intolerance (HIT) is the term for that type of food intolerance which includes a set of undesirable reactions as a result of accumulated or ingested histamine. Manifestations may be caused by various pathophysiological mechanisms or a combination of them. The problem with a "diagnosis" of HIT is precisely the inconstancy and variety of the manifestations in the same individual following similar stimuli. The diagnosing of HIT therefore requires a complex time-demanding multidisciplinary approach, including the systematic elimination of disorders with a similar manifestation of symptoms. Among therapeutic approaches, the gold standard is a low-histamine diet. A good response to such a diet is considered to be confirmation of HIT. Alongside the dietary measures, DAO supplementation supporting the degradation of ingested histamine may be considered as subsidiary treatment for individuals with intestinal DAO deficiency. If antihistamines are indicated, the treatment should be conscious and time-limited, while 2nd or 3rd generation of H1 antihistamines should take precedence.

Downregulation of Polyamine and Diamine Oxidases in Silicon-Treated Cucumber

Silicon (Si) is a ubiquitous element in soil with well-known beneficial effects under certain conditions, in several plant species, if supplied in available form for uptake. It may alleviate damage in various stress situations and may also promote growth when no obvious stressors are applied. Effects of Si are often linked to mitigation of oxidative stress, in particular to the induction of antioxidant defense mechanisms. In the work presented, the impact of silicon provision on pro-oxidant systems was investigated in cucumber. Plants of the F1 cultivar hybrid 'Joker' were grown under in vitro conditions in the absence of any applied external stressor. Silicon provision decreased H2O2 content and lowered lipid peroxidation in the leaves of the treated plants. This was paralleled by declining polyamine oxidase (PAO) and diamine oxidase (DAO) activities. Several PAO as well as lipoxygenase (LOX) genes were coordinately downregulated in Si-treated plants. Unlike in similar systems studied earlier, the Si effect was not associated with an increased transcript level of gene coding for antioxidant enzymes. These results suggest an inhibitory effect of Si provision on pro-oxidant amine oxidases, which may decrease the level of reactive oxygen species by retarding their production. This extends the molecular mechanisms linked to silicon effects onto redox balance in plants.

Relationship between allergic rhinitis and diamine oxidase activity: A preliminary report

AIM

To analyze the diamine oxidase (DAO), the main catabolic enzyme of histamine, degradation activity and its relation with symptoms of persistent allergic rhinitis.

METHODS

In this descriptive and analytical observational study, we collected DAO activity levels and the nasal peak inspiratory flow.

RESULTS

Enzymatic activity deficit in 108 patients was 46.3% (95% CI, 0.44 - 0.63), 33.33% in mild and 47.92% in moderate/severe rhinitis (p = 0.376). The nasal peak inspiratory flow in patients with a deficit in DAO activity was 76.30 ± 28.40 L/min compared to 93.62 ± 37.50 L/min in patients with normal enzymatic activity (p = 0.010).

CONCLUSIONS

It seems that the lower the catabolic activity of DAO, the lower the nasal peak inspiratory flow observed. Although DAO activity levels could be a severity biomarker in allergic rhinitis, a cause-effect association cannot be concluded. The enzyme could be another actor in the pathophysiology of allergic rhinitis.

Metabolome and lipidome derangements during a severe mast cell activation event in a patient with indolent systemic mastocytosis

BACKGROUND

The number of mast cells in various organs is elevated manifold in individuals with systemic mastocytosis. Degranulation can lead to life-threatening symptomatology. No data about the alterations of the metabolome and lipidome during an attack have been published.

OBJECTIVE

Our aim was to analyze changes in metabolomics and lipidomics during the acute phase of a severe mast cell activation event.

METHODS

A total of 43 metabolites and 11 lipid classes comprising 200 subvariants from multiple plasma samples in duplicate, covering 72 hours of a severe mast cell activation attack with nausea and vomiting, were compared with 2 baseline samples by using quantitative liquid chromatography-mass spectrometry.

RESULTS

A strong enterocyte dysfunction reflected in an almost 20-fold reduction in the functional small bowel length was extrapolated from strongly reduced ornithine and citrulline concentrations and was very likely secondary to severe endothelial cell dysfunction with hypoperfusion and extensive vascular leakage. Highly increased histamine and lactate concentrations accompanied the peak in clinical symptoms. Elevated asymmetric and symmetric dimethylarginine levels combined with reduced arginine levels compromised endothelial nitric oxide synthase activity and nitric oxide signaling. Specific and extensive depletion of many lysophosphatidylcholine variants indicates localized autotaxin activation and lysophosphatidic acid release. A strong correlation of clinical parameters with histamine concentrations and symptom reduction after 100-fold elevated plasma diamine oxidase concentrations implies that histamine is the key driver of the acute phase.

CONCLUSIONS

Rapid elimination of elevated histamine concentrations through use of recombinant human diamine oxidase, supplementation of lysophosphatidylcholine for immunomodulation, inhibition of autotaxin activity, and/or blockade of lysophosphatidic acid receptors might represent new treatment options for life-threatening mast cell activation events.

Histamine Intolerance Originates in the Gut

Histamine intolerance (HIT) is assumed to be due to a deficiency of the gastrointestinal (GI) enzyme diamine oxidase (DAO) and, therefore, the food component histamine not being degraded and/or absorbed properly within the GI tract. Involvement of the GI mucosa in various disorders and diseases, several with unknown origin, and the effects of some medications seem to reduce gastrointestinal DAO activity. HIT causes variable, functional, nonspecific, non-allergic GI and extra-intestinal complaints. Usually, evaluation for HIT is not included in differential diagnoses of patients with unexplained, functional GI complaints or in the here-listed disorders and diseases. The clinical diagnosis of HIT is challenging, and the thorough anamnesis of all HIT-linked complaints, using a standardized questionnaire, is the mainstay of HIT diagnosis. So far, DAO values in serum have not been established to correlate with DAO activity in the gut, but the diagnosis of HIT may be supported with determination of a low serum DAO value. A targeted dietary intervention, consisting of a histamine-reduced diet and/or supplementation with oral DAO capsules, is helpful to reduce HIT-related symptoms. This manuscript will present why histamine should also be taken into account in the differential diagnoses of patients with various diseases and disorders of unknown origin, but with association to functional gastrointestinal complaints. In this review, we discuss currently increasing evidence that HIT is primarily a gastrointestinal disorder and that it originates in the gut.

Increasing Expiratory Hydrogen in Lactose Intolerance Is Associated with Additional Food Intolerance/Malabsorption

Single and/or combined food intolerance/malabsorption may cause nonspecific, functional gastrointestinal (GI) complaints. In lactose-intolerant patients we evaluated the influence of additional food intolerance/malabsorption with hydrogen (H2) breath tests. In a retrospective analysis of charts from 279 lactose-intolerant patients, we found 128 patients with only lactose intolerance (LIT). Then, we identified 106 LIT patients with additional histamine intolerance (HIT). Additionally, 45 LIT and HIT patients also had fructose malabsorption (FM). A hydrogen (H2) breath test was performed to evaluate LIT and FM. A serum diamine oxidase value of <10 U/mL and a response to a histamine-reduced diet was used to identify HIT. Using pairwise comparison with the Kruskal-Wallis test to associate the area under the curve (AUC) of LIT patients and, LIT with HIT, to LIT with HIT and FM it was found, that the exhaled hydrogen values were significantly higher in patients with two-fold and triple combined food intolerance/malabsorption (p < 0.004 and p < 0.001, respectively). Within the pool of 170 LIT patients with >20 ppm increase of expiratory H2 from baseline, there were 74 LIT-only patients, 60 LIT with HIT patients, and 36 LIT patients with additional HIT and FM. With the Kruskal-Wallis test AUCs demonstrated a significant difference between all three groups (p = 0.024). In patients with LIT, the presence of additional food intolerance/malabsorption, significantly increases expiratory H2 values. We demonstrate evidence, which may suggest HIT to embody an own GI disorder as food intolerance/malabsorption.

Astrocytes Control Sensory Acuity via Tonic Inhibition in the Thalamus

Sensory discrimination is essential for survival. However, how sensory information is finely controlled in the brain is not well defined. Here, we show that astrocytes control tactile acuity via tonic inhibition in the thalamus. Mechanistically, diamine oxidase (DAO) and the subsequent aldehyde dehydrogenase 1a1 (Aldh1a1) convert putrescine into GABA, which is released via Best1. The GABA from astrocytes inhibits synaptically evoked firing at the lemniscal synapses to fine-tune the dynamic range of the stimulation-response relationship, the precision of spike timing, and tactile discrimination. Our findings reveal a novel role of astrocytes in the control of sensory acuity through tonic GABA release.

Relationship between postnatal days, serum Cu concentration and plasma diamine oxidase activity in Japanese Black calves

The aim of study was to investigate the relationships among serum diamine oxidase (DAO) activity, postnatal days and the plasma copper (Cu) concentration, using calves with or without diarrhea. In healthy calves, the serum DAO activity was significantly higher at 2 postnatal days than at ≥7 postnatal days, and no significant changes were observed after 7 postnatal days. In addition, no significant correlation was found between serum DAO activity and plasma Cu concentration at all postnatal days in healthy calves. Although, the serum DAO activity in 14 diarrheic calves (66.78 ± 14.37 IU/ml) was lower than that in 19 healthy calves (170.33 ± 97.83 IU/m, P<0.01), plasma Cu concentrations in all calves remained within the normal range.

Clinical effect of Changweishu on gastrointestinal dysfunction in patients with sepsis

Objective

To investigate Changweishu’s clinical effect on gastrointestinal dysfunction in patients with sepsis.

Methods

Fifty patients with gastrointestinal dysfunction and sepsis were randomly divided into treatment and control groups. The control group patients received routine Western medicine treatments (meropenem, noradrenaline, glutamine glue, Bifidobacterium lactis triple-strain tablet), and the treatment group patients received routine Western medicine treatment combined with Changweishu. Treatments in both groups lasted 7 days. Changes in APACHE II score, gastrointestinal dysfunction score, serum levels of diamine oxidase (DAO), D-lactic acid, inflammatory factors (tumor necrosis factor (TNF)-α, interleukin (IL)-6, and high-mobility group box 1 (HMGB-1)), and the incidence of multiple organ dysfunction syndrome (MODS) and mortality were observed.

Results

After treatment, APACHE II score, gastrointestinal dysfunction score, and DAO, D-lactic acid, TNF-α, IL-6, and HMGB-1 levels decreased significantly in both groups, but the decrease was more significant in the treatment group than in the control group. The incidence of MODS and mortality were significantly lower in the treatment group than in the control group.

Conclusion

The addition of Changweishu to routine Western treatments can improve gastrointestinal function in patients with sepsis and gastrointestinal dysfunction, as well as decreasing the incidence of MODS and mortality and improving patient prognosis.

Considering histamine in functional gastrointestinal disorders

In westernized countries, adverse reactions to ingested foods are reported to affect up to 20% of the population. Functional, nonspecific, non-allergic gastrointestinal complaints are mainly due to the intolerance/malabsorption of carbohydrates (lactose and fructose), proteins (gluten), and biogenic amines (histamine). Food intolerance/malabsorption is defined by one or several of the above mentioned food components not being degraded and/or absorbed properly within the gastrointestinal tract. Food intolerance/malabsorption causes variable, functional, nonspecific, non-allergic gastrointestinal and extra-intestinal complaints, and a detailed diagnostic workup for all possible etiologic factors in individual patients is essential. Usually, evaluation for histamine intolerance is not included in differential diagnoses of patients with functional, nonspecific, non-allergic gastrointestinal complaints. A targeted dietary intervention for single or possibly combined intolerance/malabsorption is required. In this article, we review currently discussed differential diagnoses and available tests for intolerance/malabsorption. Accordingly, we aim to outline why including histamine and, histamine intolerance, should be considered in differential diagnoses of patients with functional, nonspecific, non-allergic gastrointestinal complaints.

Accumulation of Agmatine, Spermidine, and Spermine in Sprouts and Microgreens of Alfalfa, Fenugreek, Lentil, and Daikon Radish

Sprouts and microgreens are a rich source of various bioactive compounds. Seeds of lentil, fenugreek, alfalfa, and daikon radish seeds were germinated and the contents of the polyamines agmatine (AGM), putrescine (PUT), cadaverine (CAD), spermidine (SPD), and spermine (SPM) in ungerminated seeds, sprouts, and microgreens were determined. In general, sprouting led to the accumulation of the total polyamine content. The highest levels of AGM (5392 mg/kg) were found in alfalfa microgreens, PUT (1079 mg/kg) and CAD (3563 mg/kg) in fenugreek sprouts, SPD (579 mg/kg) in lentil microgreens, and SPM (922 mg/kg) in fenugreek microgreens. A large increase in CAD content was observed in all three legume sprouts. Conversely, the nutritionally beneficial polyamines AGM, SPD, and SPM were accumulated in microgreens, while their contents of CAD were significantly lower. In contrast, daikon radish sprouts exhibited a nutritionally better profile of polyamines than the microgreens. Freezing and thawing of legume sprouts resulted in significant degradation of CAD, PUT, and AGM by endogenous diamine oxidases. The enzymatic potential of fenugreek sprouts can be used to degrade exogenous PUT, CAD, and tyramine at pH values above 5.

Novel approach using activated cellulose film for efficient immobilization of purified diamine oxidase to enhance enzyme performance and stability

The presence of various contaminants in foodstuffs has led to serious public health concerns. Diamine oxidase (DAO) has attracted tremendous attention for guarding food safety as well as clinical and environmental industries. In this study, DAO from Pisum sativum (Pea) seedlings was extracted and purified by dialysis and gel filtration. Purified DAO was covalently immobilized onto the surface of nitrocellulose membrane using glutaraldehyde. The obtained bioaffinity support has efficiently shown high yield immobilization of DAO from pea seedlings. The optimal conditions of free and immobilized DAO activity were evaluated against the substrate, Putrescine dihydrochloride. The influence of pH, temperature, storage stability, and reusability of immobilized enzyme with comparison to the free enzyme was studied and the results showed that the stabilities were significantly enhanced compared with free counterpart. Residual activity of the immobilized enzyme was 59% of the initial activity after being recycled 10 times. We approve that this novel low cost immobilized DAO carrier presents a new approach in large scale applications.

Human Copper-Containing Amine Oxidases in Drug Design and Development

Two members of the copper-containing amine oxidase family are physiologically important proteins: (1) Diamine oxidase (hDAO; AOC1) with a preference for diamines is involved in degradation of histamine and (2) Vascular adhesion protein-1 (hVAP-1; AOC3) with a preference for monoamines is a multifunctional cell-surface receptor and an enzyme. hVAP-1-targeted inhibitors are designed to treat inflammatory diseases and cancer, whereas the off-target binding of the designed inhibitors to hDAO might result in adverse drug reactions. The X-ray structures for both human enzymes are solved and provide the basis for computer-aided inhibitor design, which has been reported by several research groups. Although the putative off-target effect of hDAO is less studied, computational methods could be easily utilized to avoid the binding of VAP-1-targeted inhibitors to hDAO. The choice of the model organism for preclinical testing of hVAP-1 inhibitors is not either trivial due to species-specific binding properties of designed inhibitors and different repertoire of copper-containing amine oxidase family members in mammalian species. Thus, the facts that should be considered in hVAP-1-targeted inhibitor design are discussed in light of the applied structural bioinformatics and structural biology approaches.

Evaluation of porcine diamine oxidase for the conversion of histamine in food-relevant amounts

Histamine exists in a multitude of foods and displays an emerging role within food intolerances. Our aim was to identify the activity of porcine diamine oxidase (DAO) required for the in vitro degradation of histamine amounts that are found in typical meals containing histamine (75 mg, equaled 150 mg/L). Furthermore, we investigated an actual dietary supplement that is commercially available for histamine intolerant individuals for its histamine reduction capability. Kinetic investigations of porcine DAO showed a substrate inhibition by histamine concentrations greater than 56 mg/L (0.5 mM). The stability of free porcine DAO was tested in a fed state simulated intestinal fluid and exhibited a half-life period of around 19 min. A total of 50 nanokatal (nkat) free porcine DAO, which equaled the amount of enzyme isolated from around 100 g pig kidney, were necessary for the in vitro reduction of around 90% of the histamine. The dietary supplement that contains a pig kidney extract did not show DAO activity. Instead, the used histamine (0.75 mg) was apparently reduced due to the adsorption of histamine onto a capsule component by 18.9 ± 2.3% within 5 hr. Although the capsule preparation retained its overall structure and shape for at least 90 min in simulated gastric fluid, the apparent histamine reduction was significantly reduced to 12.1 ± 2.3% (P ≤ 0.05). In conclusion, an alternative to the pig kidney DAO or an improved capsule preparation is needed to ensure an adequate supplementation for histamine-intolerant humans. PRACTICAL APPLICATION: Histamine intolerance is an emerging issue in our society and the intolerance-related physiological symptoms are currently not reliably treatable due to a lack of scientific investigation. A commercially available dietary supplement for histamine intolerance does not fulfil the requirements for a satisfactory histamine reduction in intolerant humans. The activity of the histamine degrading enzyme diamine oxidase, required for a satisfactory histamine degradation, is by far higher than the theoretical amount apparently given in the dietary supplement. With this knowledge, it is obvious that improved food supplements must be developed to help histamine intolerant humans.

Thermospermine Synthase (ACL5) and Diamine Oxidase (DAO) Expression Is Needed for Zygotic Embryogenesis and Vascular Development in Scots Pine

Unlike in flowering plants, the detailed roles of the enzymes in the polyamine (PA) pathway in conifers are poorly known. We explored the sequence conservation of the PA biosynthetic genes and diamine oxidase (DAO) in conifers and flowering plants to reveal the potential functional diversification of the enzymes between the plant lineages. The expression of the genes showing different selective constraints was studied in Scots pine zygotic embryogenesis and early seedling development. We found that the arginine decarboxylase pathway is strongly preferred in putrescine production in the Scots pine as well as generally in conifers and that the reduced use of ornithine decarboxylase (ODC) has led to relaxed purifying selection in ODC genes. Thermospermine synthase (ACL5) genes evolve under strong purifying selection in conifers and the DAO gene is also highly conserved in pines. In developing Scots pine seeds, the expression of both ACL5 and DAO increased as embryogenesis proceeded. Strong ACL5 expression was present in the procambial cells of the embryo and in the megagametophyte cells destined to die via morphologically necrotic cell death. Thus, the high sequence conservation of ACL5 genes in conifers may indicate the necessity of ACL5 for both embryogenesis and vascular development. Moreover, the result suggests the involvement of ACL5 in morphologically necrotic cell death and supports the view of the genetic regulation of necrosis in Scots pine embryogenesis and in plant development. DAO transcripts were located close to the cell walls and between the walls of adjacent cells in Scots pine zygotic embryos and in the roots of young seedlings. We propose that DAO, in addition to the role in Put oxidation for providing H2O2 during the cell-wall structural processes, may also participate in cell-to-cell communication at the mRNA level. To conclude, our findings indicate that the PA pathway of Scots pines possesses several special functional characteristics which differ from those of flowering plants.

Impaired resolution of wheals in the skin prick test and low diamine oxidase blood level in allergic patients

Introduction

Histamine is the major mediator of IgE- and non-IgE-mediated allergic reactions upon allergen or hapten contact. Reduced histamine degradation capacity was associated with atopic eczema as well as with non-immunological histamine intolerance. Higher blood serum histamine level concomitant with decreased intestinal diamine oxidase activity were observed in patients with food allergy.

Aim

To evaluate the relationship between patients’ blood diamine oxidase (DAO) activity/histamine status and their reactivity to time-resolved histamine skin prick test in respect to vulnerability to allergic diseases.

Material and methods

Fifty-three patients were examined with skin prick tests (SPT) and patch tests for suspected presence of either IgE- or non-IgE-mediated allergy. All individuals were skin prick tested with histamine and the resolution of the wheal was monitored for 50 min. Blood DAO activity and histamine concentration were measured with a radio-extraction radioimmunoassay.

Results

Time-resolved histamine skin prick testing revealed presence of wheals which were 35% larger in diameter in 47% of examined subjects at 20 min of the test. These patients exhibited significantly compromised time-course wheal resolution (wheal ≥ 3 mm at 50 min) compared to a group of patients with the normal-rate of wheal resolution (wheal = 0 mm at 50 min). Within a group of subjects exhibiting impaired wheal resolution, 61% of patients were diagnosed allergic compared to 50% in a group of patients with a normal rate of wheal resolution. Finally, allergic patients were characterized by a significantly lower DAO activity and higher histamine content compared to healthy subjects.

Conclusions

The results of this study indicate that patients with IgE- or non-IgE-mediated allergy are likely to have low DAO blood activity and may concomitantly suffer from histamine intolerance. Furthermore, our results suggest that allergic patients are more likely to develop an excessive SPT reaction. Our results emphasize caution in interpretation of the SPT results in allergic patients with diagnosed histamine intolerance or histamine/DAO activity imbalance.

Diamine oxidase enzyme: a novel biomarker in respiratory allergy

BACKGROUND

Well-known allergy tests are used to evaluate and diagnose allergic diseases. The aim of this study was to assess the role of serum level diamine oxidase (DAO) enzyme as a diagnostic marker in respiratory allergy.

METHODS

This case-control study included 40 patients with respiratory allergies (atopic asthma and allergic rhinitis) as well as 40 age- and sex-matched controls. A detailed past medical history of allergy was collected from each participant including family history of allergy. Physical examination, pulmonary function test (PFT) and measurement of serum levels of total immunoglobulin E (IgE) and DAO were performed. Skin-prick test and specific IgE to common aeroallergens were also carried out.

RESULTS

DAO levels were higher in patients than controls. There was a positive correlation between severity of disease and DAO. No significant association was found between DAO level and age, type of respiratory allergy, duration of disease, PFT, eosinophilia, and total IgE. DAO had a high negative predictive value (94.7%) and high sensitivity (97.5%).

CONCLUSION

DAO may be helpful in the assessment of severity and in ruling out respiratory allergy.

Massive release of the histamine-degrading enzyme diamine oxidase during severe anaphylaxis in mastocytosis patients

Background

Histaminolytic activity mediated by diamine oxidase (DAO) is present in plasma after induction of severe anaphylaxis in rats, guinea pigs, and rabbits. Heparin released during mast cell degranulation in the gastrointestinal tract might liberate DAO from heparin‐sensitive storage sites. DAO release during anaphylaxis has not been demonstrated in humans.

Methods

Plasma DAO, tryptase, and histamine concentrations of four severe anaphylaxis events were determined at multiple serial time points in two patients with systemic mastocytosis. The histamine degradation rates were measured in anaphylaxis samples and in pregnancy sera and plasma with comparable DAO concentrations.

Results

Mean DAO (132 ng/mL) and tryptase (304 ng/mL) concentrations increased 187‐ and 4.0‐fold, respectively, over baseline values (DAO 0.7 ng/mL, tryptase 76 ng/mL) during severe anaphylaxis. Under non‐anaphylaxis conditions, DAO concentrations were not elevated in 29 mastocytosis patients compared to healthy volunteers and there was no correlation between DAO and tryptase levels in mastocytosis patients. The histamine degradation rate of DAO in plasma from mastocytosis patients during anaphylaxis is severely compromised compared to DAO from pregnancy samples.

Conclusion

During severe anaphylaxis in mastocytosis patients, DAO is likely released from heparin‐sensitive gastrointestinal storage sites. The measured concentrations can degrade histamine, but DAO activity is compromised compared to pregnancy samples. For accurate histamine measurements during anaphylaxis, DAO inhibition is essential to inhibit further histamine degradation after blood withdrawal. Determination of DAO antigen levels might be of clinical value to improve the diagnosis of mast cell activation.

Building Microbial Hosts for Heterologous Production of N-Methylpyrrolinium

N-Methylpyrrolinium-derived alkaloids like tropane alkaloids, nicotine, and calystegines are valuable plant source specialized metabolites bearing pharmaceutical or biological activity. Microbial synthesis of the critical common intermediate N-methylpyrrolinium would allow for sustainable production of N-methylpyrrolinium-derived alkaloids. Here, we achieve the production of N-methylpyrrolinium both in Escherichia coli and in Saccharomyces cerevisiae by employing the biosynthetic genes derived from three different plants. Specifically, the diamine oxidases (DAOs) from Anisodus acutangulus were first characterized. Then, we produced N-methylpyrrolinium in vitro from l-ornithine via a combination of the three cascade enzymes, ornithine decarboxylase from Erythroxylum coca, putrescine N-methyltransferase from Anisodus tanguticus, and DAOs from A. acutangulus. Construction of the plant biosynthetic pathway in E. coli and S. cerevisiae resulted in de novo bioproduction of N-methylpyrrolinium with titers of 3.02 and 2.07 mg/L, respectively. Metabolic engineering of the yeast strain to produce N-methylpyrrolinium via decreasing the flux to the product catabolism pathway and improving the cofactor supply resulted in a final titer of 17.82 mg/L. This study not only presents the first microbial synthesis of N-methylpyrrolinium but also lays the foundation for heterologous biosynthesis of N-methylpyrrolinium-derived alkaloids. More importantly, the strains constructed herein can serve as important alternative tools for identifying undiscovered pathway enzymes with a synthetic biology strategy.

Histamine N-Methyltransferase in the Brain

Brain histamine is a neurotransmitter and regulates diverse physiological functions. Previous studies have shown the involvement of histamine depletion in several neurological disorders, indicating the importance of drug development targeting the brain histamine system. Histamine N-methyltransferase (HNMT) is a histamine-metabolising enzyme expressed in the brain. Although pharmacological studies using HNMT inhibitors have been conducted to reveal the direct involvement of HNMT in brain functions, HNMT inhibitors with high specificity and sufficient blood–brain barrier permeability have not been available until now. Recently, we have phenotyped Hnmt-deficient mice to elucidate the importance of HNMT in the central nervous system. Hnmt disruption resulted in a robust increase in brain histamine concentration, demonstrating the essential role of HNMT in the brain histamine system. Clinical studies have suggested that single nucleotide polymorphisms of the human HNMT gene are associated with several brain disorders such as Parkinson’s disease and attention deficit hyperactivity disorder. Postmortem studies also have indicated that HNMT expression is altered in human brain diseases. These findings emphasise that an increase in brain histamine levels by novel HNMT inhibitors could contribute to the improvement of brain disorders.

Serum levels of histamine and diamine oxidase in multiple sclerosis

BACKGROUND

Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system, mostly affecting young adults. Diamine oxidase is an enzyme essential for histamine production. Histamine which is produced mostly by mast cells can have effects on different aspects of immune system via its different histamine receptors (H1R, H2R, H3R and H4R). The crucial role of diamine oxidase and histamine in immune balance has been documented in different studies and experiments both on MS patients and on experimental allergic encephalomyelitis (EAE). In this regard, we aimed to measure the level of histamine and diamine oxidase in the serum of MS patients.

METHODS

A total number of 50 relapsing-remitting MS (RRMS) patients and 41 age and sex matched controls were enrolled in this study. Assessments of serum levels of histamine and diamine oxidase enzyme were performed using enzyme-linked immune sorbent assay (ELISA).

RESULTS

The serum levels of histamine and diamine oxidase in RRMS patients were lower than healthy controls (P-value = 0.00, for both).

CONCLUSION

Our research team found significant low levels of histamine and diamine oxidase in RRMS patients; however the pathogenesis of this issue was unclear.

Stability of Vegetal Diamine Oxidase in Simulated Intestinal Media: Protective Role of Cholic Acids

Food biogenic amines, in particular, histamine, are often responsible for various enteric and vascular dysfunctions. Several years ago, the oral administration of copper-containing diamine oxidase (DAO), also called histaminase, able to oxidatively deaminate biogenic amines, had been suggested as a food supplement to control food allergy and enteric dysfunctions. This report is aimed to generate a global image on the behavior of orally administrated DAO dosage forms in the intestinal tract. The catalytic stability of DAO from Lathyrus sativus seedlings in various simulated intestinal media with different pH and containing different association of cholic acids, pancreatic proteases, bicarbonate, lipids, or alcohol was investigated. Cholic acids and lipids protected the enzyme in the simulated intestinal fluids. However, they were not able to protect against the inhibitory effect of 24-36% (v/v) ethanol. These observations may be relevant for oral administration of enzymes as food supplements or therapeutic bioactive agents.

Nutrition therapy for adverse reactions to histamine in food and beverages

Adverse reactions to food are suspected in one third of the German population, but only 10% of these assumed hypersensitivity reactions can be clinically confirmed. While diagnosis of food allergies is fairly easy due to objective laboratory parameters, non-allergic hypersensitivity reactions are difficult to diagnose because these objective markers are lacking so far. Adverse reactions to histamine are often suspected to be the cause of a wide range of symptoms, especially when no allergic pathomechanism can be identified. In order to confirm such a suspicion, it is inevitable to validate a reproducible association between consumption of histamine-rich food and beverages and symptoms to identify causative agents and to exclude other disorders. Thereafter, avoidance tests should be performed on the basis of individual requirements. General advice with a lot of restraints is often unnecessarily strict. Nutrition therapy aims at a reduction of symptoms to a minimum while maintaining a high quality of life.

Conformational Design and Characterisation of a Truncated Diamine Oxidase from Arthrobacter globiformis

A functional mini protein can be developed by miniaturising its size. The minimisation technique provides an excellent model system for studying native enzymes, especially in creating an alternative novel biocatalyst. Miniaturised proteins may have enhanced stability, a crucial characteristic for large-scale production and industrial applications. In this study, a huge enzyme molecule, known as diamine oxidase (DAO, comprising 700 amino acids), was selected to undergo the process. By retaining the arrangement of the original functional sites of DAO in the fourth domain, a mini DAO can be designed via homology modelling. After several downsizing processes, a final configuration of 220 amino acids displayed high binding affinity towards histamine, a short-chain substrate that was catalysed by the parental DAO. The configuration also showed enhanced affinity towards a long-chain substrate known as spermidine. The gene for the designed protein was cloned and expressed in pET102/TOPO vector and overexpressed in E. coli BL21 (DE3). The new mini DAO had similar temperature tolerance and versatile substrates specificity characteristics as its parental protein. An active mini-protein with these characteristics is potentially useful for several applications such as detecting biogenic amines in the biological fluids and the environment that may give rise to health issues.

Laser Scribed Graphene Biosensor for Detection of Biogenic Amines in Food Samples Using Locally Sourced Materials

In foods, high levels of biogenic amines (BA) are the result of microbial metabolism that could be affected by temperatures and storage conditions. Thus, the level of BA is commonly used as an indicator of food safety and quality. This manuscript outlines the development of laser scribed graphene electrodes, with locally sourced materials, for reagent-free food safety biosensing. To fabricate the biosensors, the graphene surface was functionalized with copper microparticles and diamine oxidase, purchased from a local supermarket; and then compared to biosensors fabricated with analytical grade materials. The amperometric biosensor exhibits good electrochemical performance, with an average histamine sensitivity of 23.3 µA/mM, a lower detection limit of 11.6 µM, and a response time of 7.3 s, showing similar performance to biosensors constructed from analytical grade materials. We demonstrated the application of the biosensor by testing total BA concentration in fish paste samples subjected to fermentation with lactic acid bacteria. Biogenic amines concentrations prior to lactic acid fermentation were below the detection limit of the biosensor, while concentration after fermentation was 19.24 ± 8.21 mg histamine/kg, confirming that the sensor was selective in a complex food matrix. The low-cost, rapid, and accurate device is a promising tool for biogenic amine estimation in food samples, particularly in situations where standard laboratory techniques are unavailable, or are cost prohibitive. This biosensor can be used for screening food samples, potentially limiting food waste, while reducing chances of foodborne outbreaks.