Histamine Intolerance Originates in the Gut

Pilot Study on the Prevalence of Diamine Oxidase Gene Variants in Patients with Symptoms of Histamine Intolerance

A retrospective pilot study was carried out to investigate the prevalence of four variants of the diamine oxidase (DAO) encoding gene (AOC1) in Caucasian adults with symptoms of histamine intolerance. In a cohort of 100 patients and 100 healthy individuals, DAO-encoding gene non-synonymous Single Nucleotide Variations (SNVs) were genotyped by multiplex single-nucleotide primer extension (SNPE) and capillary electrophoresis, and serum DAO activity was analyzed with a radio-extraction assay. The study found that 79% of individuals with symptoms of histamine intolerance harbored one or more of the four SNVs associated with reduced DAO activity. No significant differences were found in the prevalence of any variant between the group of patients and healthy controls. However, when considering the status of the alleles associated with DAO deficiency, more homozygous alleles were observed in histamine-intolerant patients. Moreover, a slightly but statistically higher percentage of patients had a high genetic risk score, reflecting the cumulative effect of carrying multiple DAO deficiency-associated gene variants and a high load of risk alleles (homozygous). A relationship between serum DAO activity and the genetic load of one specific SNV was observed, with DAO activity being significantly lower in patients homozygous for rs2052129. These results potentially support that carrying multiple DAO deficiency-associated gene variants and a high load of risk alleles (homozygous) is more relevant than the mere presence of one or more SNVs. Further studies are needed to determine the predictive value of these DAO-encoding gene variants.

Is calcitonin gene-related peptide (CGRP) the missing link in food histamine-induced migraine? A review of functional gut-to-trigeminovascular system connections

Calcitonin gene-related peptide (CGRP) and histamine plasma concentrations increase during migraine attacks. Both mediators are potent vasodilators, and they have been shown to reciprocally contribute to the release of each other in the trigeminovascular system, possibly driving migraine development. A high-histamine-content diet triggers migraine in patients who have histamine degradation deficiency owing to diaminooxidase (DAO) gene mutations. Therefore, studying functional links between exogenous histamine and CGRP seems promising for the understanding of diet-induced migraine generation. Notably, there is a lack of knowledge about the interplay of the enteric nervous system and the spinal/trigeminal somatosensory system with regard to CGRP and histamine. Based on background evidence, we propose that a functional interconnection between exogenous histamine and CGRP contributes to migraine development.

Enhanced mucosal mitochondrial function corrects dysbiosis and OXPHOS metabolism in IBD

Background

Mitochondrial (Mito) dysfunction in IBD reduces mucosal O2 consumption and increases O2 delivery to the microbiome. Increased enteric O2 promotes blooms of facultative anaerobes (eg. Proteobacteria ) and restricts obligate anaerobes (eg. Firmicutes ). Dysbiotic metabolites negatively affect host metabolism and immunity. Our novel compound (AuPhos) upregulates intestinal epithelial cell (IEC) mito function, attenuates colitis and corrects dysbiosis in humanized Il10-/- mice. We posit that AuPhos corrects IBD-associated dysbiotic metabolism.

Methods

Primary effect of AuPhos on mucosal Mito respiration and healing process was studied in ex vivo treated human colonic biopsies and piroxicam-accelerated (Px) Il10-/- mice. Secondary effect on microbiome was tested in DSS-colitis WT B6 and germ-free 129.SvEv WT or Il10-/- mice reconstituted with human IBD stool (Hu- Il10-/- ). Mice were treated orally with AuPhos (10- or 25- mg/kg; q3d) or vehicle, stool samples collected for fecal lipocalin-2 (f-LCN2) assay and microbiome analyses using 16S rRNA sequencing. AuPhos effect on microbial metabolites was determined using untargeted global metabolomics. AuPhos-induced hypoxia in IECs was assessed by Hypoxyprobe-1 staining in sections from pimonidazole HCl-infused DSS-mice. Effect of AuPhos on enteric oxygenation was assessed by E. coli Nissle 1917 WT (aerobic respiration-proficient) and cytochrome oxidase (cydA) mutant (aerobic respiration-deficient).

Results

Metagenomic (16S) analysis revealed AuPhos reduced relative abundances of Proteobacteria and increased blooms of Firmicutes in uninflamed B6 WT, DSS-colitis, Hu-WT and Hu- Il10-/- mice. AuPhos also increased hypoxyprobe-1 staining in surface IECs suggesting enhanced O2 utilization. AuPhos-induced anaerobiosis was confirmed by a significant increase in cydA mutant compared to WT (O2-utlizing) E.coli . Ex vivo treatment of human biopsies with AuPhos showed significant increase in Mito mass, and complexes I and IV. Further, gene expression analysis of AuPhos-treated biopsies showed increase in stem cell markers (Lgr4, Lgr5, Lrig1), with concomitant decreases in pro-inflammatory markers (IL1β,MCP1, RankL). Histological investigation of AuPhos-fed Px- Il10-/- mice showed significantly decreased colitis score in AuPhos-treated Px- Il10-/- mice, with decrease in mRNA of pro-inflammatory cytokines and increase in Mito complexes ( ND5 , ATP6 ). AuPhos significantly altered microbial metabolites associated with SCFA synthesis, FAO, TCA cycle, tryptophan and polyamine biosynthesis pathways. AuPhos increased pyruvate, 4-hydroxybutyrate, 2-hydroxyglutarate and succinate, suggesting an upregulation of pyruvate and glutarate pathways of butyrate production. AuPhos reduced IBD-associated primary bile acids (BA) with concomitant increase in secondary BA (SBA). AuPhos treatment significantly decreased acylcarnitines and increased L-carnitine reflective of enhanced FAO. AuPhos increases TCA cycle intermediates and creatine, energy reservoir substrates indicating enhanced OxPHOS. Besides, AuPhos also upregulates tryptophan metabolism, decreases Kynurenine and its derivatives, and increases polyamine biosynthesis pathway (Putresceine and Spermine).

Conclusion

These findings indicate that AuPhos-enhanced IEC mitochondrial function reduces enteric O2 delivery, which corrects disease-associated metabolomics by restoring short-chain fatty acids, SBA, AA and IEC energy metabolism.

Graphical abstract

Ageratina adenophora causes intestinal integrity damage in goats via the activation of the MLCK/ROCK signaling pathway

As a global toxin invasive species, the whole herb of Ageratina adenophora (A. adenophora) contains various sesquiterpenes, which can cause various degrees of toxic reactions characterized by inflammatory damage when ingested by animals. Current studies on the toxicity of A. adenophora have focused on parenchymatous organs such as the liver and spleen, but few studies have been conducted on the intestine as the organ that is first exposed to A. adenophora and digests and absorbs its toxic components. In this study, after feeding goats with 40 % A. adenophora herb powder for 90 d, we found that the intestinal structure of goats showed pathological changes characterized, and the damage to the small intestinal segments was more severe than that of the large intestine. The MLCK/ROCK signaling pathway was activated, the cytoskeleton underwent centripetal contraction, the composition of tight junctions between intestinal epithelial cells was altered table, Occludin, Claudin-1 and Zonula occluden (ZO-1) amount was decreased, and the intestinal mechanical barrier was disrupted. The intestinal damage markers diamine oxidase (DAO) and D-lactate (D-LA) levels were elevated. In addition, we also found that intestinal bacteria translocate and enter the portal vein to colonize the liver and mesenteric lymph nodes. The expression of intestinal pro-inflammatory factors and anti-inflammatory factors was changed, the intestinal immune function was disrupted. The present study is the first to analyze the mechanism of poisoning of A. adenophora from the intestinal tract in compound-gastric animals.

Adverse Food Reactions in Inflammatory Bowel Disease: State of the Art and Future Perspectives

Limited knowledge is available about the relationship between food allergies or intolerances and inflammatory bowel disease (IBD). Clinicians frequently encounter patients who report food allergies or intolerances, and gastroenterologists struggle distinguishing between patients with organic disorders and those with functional disorders, which the patients themselves may associate with specific dietary components. This task becomes even more arduous when managing patients with significant underlying organic conditions, like IBD. The aim of this review is to summarize and emphasize any actual associations between food allergies and intolerances and inflammatory diseases, such as ulcerative colitis and Crohn's disease. Through a narrative disceptation of the current literature, we highlight the increased prevalence of various food intolerances, including lactose, fructose, histamine, nickel, and non-celiac gluten sensitivity, in individuals with IBD. Additionally, we explore the association between increased epithelial barrier permeability in IBD and the development of food sensitization. By doing so, we aim to enhance clinicians' awareness of the nutritional management of patients with IBD when facing complaints or evidence of food allergies or intolerances.

Food Intolerances, Food Allergies and IBS: Lights and Shadows

This narrative review delves into the intricate relationship between irritable bowel syndrome (IBS) and food intolerances. IBS, a chronic functional gastrointestinal disorder, is characterized by symptoms like abdominal pain and altered bowel habits. The prevalence of IBS has increased globally, especially among young adults. Food and dietary habits play a crucial role in IBS management. About 85-90% of IBS patients report symptom exacerbation linked to specific food consumption, highlighting the strong connection between food intolerances and IBS. Food intolerances often exhibit a dose-dependent pattern, posing a challenge in identifying trigger foods. This issue is further complicated by the complex nature of gastrointestinal physiology and varying food compositions. This review discusses various dietary patterns and their impact on IBS, including the low-FODMAP diet, gluten-free diet, and Mediterranean diet. It highlights the importance of a personalized approach in dietary management, considering individual symptom variability and dietary history. In conclusion, this review emphasizes the need for accurate diagnosis and holistic management of IBS, considering the complex interplay between dietary factors and gastrointestinal pathophysiology. It underlines the importance of patient education and adherence to treatment plans, acknowledging the challenges posed by the variability in dietary triggers and the psychological impact of dietary restrictions.

Gut microbiota and metabolic modulation by supplementation of polysaccharide-producing Bacillus licheniformis from Tibetan Yaks: A comprehensive multi-omics analysis

Gut microbiota and their metabolic processes depend on the intricate interplay of gut microbiota and their metabolic processes. Bacillus licheniformis, a beneficial food supplement, has shown promising effects on stabilizing gut microbiota and metabolites. However, the precise mechanisms underlying these effects remain elusive. In this study, we investigated the impact of polysaccharide-producing B. licheniformis as a dietary supplement on the gut microbiome and metabolites through a combination of scanning electron microscopy (SEM), histological analysis, high-throughput sequencing (HTS), and metabolomics. Our findings revealed that the B. licheniformis-treated group exhibited significantly increased jejunal goblet cells. Moreover, gut microbial diversity was lower in the treatment group as compared to the control, accompanied by noteworthy shifts in the abundance of specific bacterial taxa. Enrichment of Firmicutes, Lachnospiraceae, and Clostridiales_bacterium contrasted with reduced levels of Campylobacterota, Proteobacteria, Parasutterella, and Helicobacter. Notably, the treatment group showed significant weight gain after 33 days, emphasizing the polysaccharide's impact on host metabolism. Delving into gut metabolomics, we discovered significant alterations in metabolites. Nine metabolites, including olprinone, pyruvic acid, and 2-methyl-3-oxopropanoate, were upregulated, while eleven, including defoslimod and voclosporin were down-regulated, shedding light on phenylpropanoid biosynthesis, tricarboxylic acid cycle (TCA cycle), and the glucagon signaling pathway. This comprehensive multi-omics analysis offers compelling insights into the potential of B. licheniformis as a dietary polysaccharide supplement for gut health and host metabolism, promising significant implications for gut-related issues.

Diamine Oxidase Interactions with Anti-Inflammatory and Anti-Migraine Medicines in the Treatment of Migraine

Histamine intolerance arises when there is a disparity between the production of histamine and the body's ability to break it down. In the gastrointestinal tract, the primary enzyme responsible for metabolizing ingested histamine is diamine oxidase (DAO), and a shortage of this enzyme has been associated with some diseases related to the respiratory, cardiovascular, nervous, muscular, and digestive systems, in addition to migraines. The treatment of migraines typically revolves around the utilization of both anti-migraine and anti-inflammatory drugs, but their interaction with DAO is not thoroughly understood. In this study, we examined the impact of nonsteroidal anti-inflammatory drugs (NSAIDs) and anti-migraine medications on DAO activity through in vitro experiments. We also investigated their effects on the human intestinal cell line Caco-2, assessing changes in DAO expression (both at the mRNA and protein levels) as well as DAO activity. The tested drugs, including ibuprofen, acetylsalicylic acid, paracetamol, a combination of acetylsalicylic acid with paracetamol and caffeine, zolmitriptan, and sumatriptan, did not inhibit DAO activity or reduce their levels. However, naproxen reduced DAO protein levels in human enterocyte cultures while not affecting DAO activity. These results suggest that combining anti-inflammatory and anti-migraine drugs with DAO enzyme supplementation for migraine patients with DAO deficiency could be beneficial for healthcare professionals in their daily practice.

Sexually Dimorphic Effects of Histamine Degradation by Enteric Glial Histamine N-Methyltransferase (HNMT) on Visceral Hypersensitivity

Histamine is a neuromodulator that affects gut motility and visceral sensitivity through intrinsic and extrinsic neural pathways, yet the mechanisms regulating histamine availability in these pathways remain poorly understood. Here, we show that enteric glia contribute to histamine clearance in the enteric nervous system (ENS) through their expression of the enzyme histamine N-methyltransferase (HNMT). Glial HNMT expression was initially assessed using immunolabeling and gene expression, and functionally tested using CRISPR-Cas9 to create a Cre-dependent conditional Hnmt ablation model targeting glia. Immunolabeling, calcium imaging, and visceromotor reflex recordings were used to assess the effects on ENS structure and visceral hypersensitivity. Immunolabeling and gene expression data show that enteric neurons and glia express HNMT. Deleting Hnmt in Sox10+ enteric glia increased glial histamine levels and altered visceromotor responses to colorectal distension in male mice, with no effect in females. Interestingly, deleting glial Hnmt protected males from histamine-driven visceral hypersensitivity. These data uncover a significant role for glial HNMT in histamine degradation in the gut, which impacts histamine-driven visceral hypersensitivity in a sex-dependent manner. Changes in the capacity of glia to clear histamines could play a role in the susceptibility to developing visceral pain in disorders of the gut-brain interaction.

Crotonis Fructus-induced gut microbiota and serum metabolic disorders in rats

Crotonis Fructus (CF), a poisonous traditional laxative, has been used to treat constipation, edema, ascites, and inflammation for more than 2000 years. However, CF possesses toxicity and its toxic mechanism is still unclear. Thus, this research explored the deleterious impacts and underlying mechanisms of CF by evaluating alterations in gut microbiota composition and metabolites. High-throughput sequencing was employed on the 16S rDNA gene to explore the intestinal flora. The untargeted metabolomics method was utilized for evaluating serum metabolomics analysis. The results showed that CF could induce obvious hepatic and gastrointestinal damage by histopathologic morphology of the liver, stomach, duodenum, and colon. According to 16S rDNA sequencing, CF can cause gut microbiota disturbance in rats, and the abundance of opportunistic pathogens such as Clostridia_UCG_014_unclassified increased significantly, while the levels of beneficial bacterial Lactobacillus remarkably declined after CF treatment. Additionally, metabolomics analysis demonstrated that CF may induce toxicity by disrupting the glycerophospholipid metabolism pathway and metabolites such as phosphatidylcholine and phosphatidylethanolamine. Moreover, a correlation study revealed the link between intestinal flora, serum metabolites, and toxicity-related biochemical markers. The results provide a new idea for the research and clinical application of toxic traditional medicine. KEY POINTS: • Crotonis Fructus could affect the gut flora and serum metabolic disruption in SD rats. • Crotonis Fructus could promote the proliferation of harmful bacteria and inhibit beneficial bacteria. • Glycerophospholipid metabolism was disturbed by Crotonis Fructus.

Linking Migraine to Gut Dysbiosis and Chronic Non-Communicable Diseases

In the world, migraine is one of the most common causes of disability in adults. To date, there is no a single cause for this disorder, but rather a set of physio-pathogenic triggers in combination with a genetic predisposition. Among the factors related to migraine onset, a crucial role seems to be played by gut dysbiosis. In fact, it has been demonstrated how the intestine is able to modulate the central nervous system activities, through the gut-brain axis, and how gut dysbiosis can influence neurological pathologies, including migraine attacks. In this context, in addition to conventional pharmacological treatments for migraine, attention has been paid to an adjuvant therapeutic strategy based on different nutritional approaches and lifestyle changes able to positively modulate the gut microbiota composition. In fact, the restoration of the balance between the different gut bacterial species, the reconstruction of the gut barrier integrity, and the control of the release of gut-derived inflammatory neuropeptides, obtained through specific nutritional patterns and lifestyle changes, represent a possible beneficial additive therapy for many migraine subtypes. Herein, this review explores the bi-directional correlation between migraine and the main chronic non-communicable diseases, such as diabetes mellitus, arterial hypertension, obesity, cancer, and chronic kidney diseases, whose link is represented by gut dysbiosis.

A personalized management approach in disorders of the irritable bowel syndrome spectrum

Symptoms of the disorders across the irritable bowel syndrome (IBS) spectrum include several different, usually postprandial, abdominal complaints. Up to date, dietary treatments of the IBS have neither been personalized nor diagnosed with sufficient scientific evidence. They have mostly been treated using 'one-size-fits-all' approaches. Such include exclusion diets, a low fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet, and gluten-free diets, lactose-free diets, a diet recommended by the UK National Institute for Health and Care Excellence, and a wheat-free diet. The exact pathophysiology of IBS disorders across the spectrum is still unclear. However, the symptom profile of IBS spectrum disorders seems similar to that of food intolerance/malabsorption syndromes. Celiac disease, fructose malabsorption, histamine intolerance and lactose intolerance represent food intolerance/malabsorption disorders based on the indigestion of sugars and/or proteins. Helicobacter pylori infection may potentially promote the development of IBS and, when facing a case of IBS-like symptoms, a search for intolerance/malabsorption and H. pylori should be added to find the correct treatment for the respective patient. This review will discuss why the 'one-size-fits-all' dietary approach in the treatment of complaints across the IBS spectrum cannot be successful. Hence, it will provide an overview of the most common overall dietary approaches currently used, and why those should be discouraged. Alternatively, a noninvasive diagnostic workup of the pathophysiologic factors of food intolerance/malabsorption in each patient with symptoms of the IBS spectrum is suggested. Additionally, if H. pylori is found, eradication therapy is mandatory, and if food intolerance/malabsorption is detected, an individual and personalized dietary intervention by a registered dietician is recommended.

Effectiveness of radiotherapy and targeted radionuclide therapy for melanoma in preclinical mouse models: A combination treatments overview

Cutaneous melanoma is an aggressive and highly metastatic skin cancer. In recent years, immunotherapy and targeted small-molecule inhibitors have improved the overall survival of patients. Unfortunately, most patients in advanced stages of disease exhibit either intrinsically resistant or rapidly acquire resistance to these approved treatments. However, combination treatments have emerged to overcome resistance, and novel treatments based on radiotherapy (RT) and targeted radionuclide therapy (TRT) have been developed to treat melanoma in the preclinical mouse model, raising the question of whether synergy in combination therapies may motivate and increase their use as primary treatments for melanoma. To help clarify this question, we reviewed the studies in preclinical mouse models where they evaluated RT and TRT in combination with other approved and unapproved therapies from 2016 onwards, focusing on the type of melanoma model used (primary tumor and or metastatic model). PubMed® was the database in which the search was performed using mesh search algorithms resulting in 41 studies that comply with the inclusion rules of screening. Studies reviewed showed that synergy with RT or TRT had strong antitumor effects, such as tumor growth inhibition and fewer metastases, also exhibiting systemic protection. In addition, most studies were carried out on antitumor response for the implanted primary tumor, demonstrating that more studies are needed to evaluate these combined treatments in metastatic models on long-term protocols.

The tale of antibiotics beyond antimicrobials: Expanding horizons

Antibiotics had proved to be a godsend for mankind since their discovery. They were once the magical solution to the vexing problem of infection-related deaths. German scientist Paul Ehrlich had termed salvarsan as the silver bullet to treatsyphilis.As time passed, the magic of newly discovered silver bullets got tarnished with raging antibiotic resistance among bacteria and associated side-effects. Still, antibiotics remain the primary line of treatment for bacterial infections. Our understanding of their chemical and biological activities has increased immensely with advancement in the research field. Non-antibacterial effects of antibiotics are studied extensively to optimise their safer, broad-range use. These non-antibacterial effects could be both useful and harmful to us. Various researchers across the globe including our lab are studying the direct/indirect effects and molecular mechanisms behind these non-antibacterial effects of antibiotics. So, it is interesting for us to sum up the available literature. In this review, we have briefed the possible reason behind the non-antibacterial effects of antibiotics, owing to the endosymbiotic origin of host mitochondria. We further discuss the physiological and immunomodulatory effects of antibiotics. We then extend the review to discuss molecular mechanisms behind the plausible use of antibiotics as anticancer agents.

Interaction of Diamine Oxidase with Psychostimulant Drugs for ADHD Management

Histamine intolerance occurs when there is an imbalance between histamine production and the capacity for histamine degradation. Diamine oxidase (DAO) is the main enzyme for the catabolism of ingested histamine degradation in the gastrointestinal tract and its deficiency has been linked to allergy-like symptoms. Psychostimulant drugs are commonly used to treat Attention Deficit Hyperactivity Disorder (ADHD), but their interaction with DAO is not well characterized. In this work, we evaluated the effects of psychostimulant drugs (methylphenidate and lisdexamfetamine) on in vitro DAO activity and in the human cell line of enterocytes (Caco-2), evaluating DAO expression (mRNA and protein) and DAO activity. Methylphenidate and lisdexamfetamine did not repress the in vitro DAO activity. In addition, in Caco-2 cells, lisdexamfetamine promoted a strong upregulation of DAO mRNA levels, whereas methylphenidate tended to induce DAO activity. To sum up, methylphenidate and lisdexamfetamine treatments do not reduce DAO activity. These findings could be useful for physicians prescribing these two drugs to ADHD patients affected by DAO deficiency.

Inflammatory Bowel Disease: Crosstalk between Histamine, Immunity, and Disease

Inflammatory bowel disease (IBD) is increasingly recognized as a serious, worldwide public health concern. It is generally acknowledged that a variety of factors play a role in the pathogenesis of this group of chronic inflammatory diseases. The diversity of molecular actors involved in IBD does not allow us to fully assess the causal relationships existing in such interactions. Given the high immunomodulatory activity of histamine and the complex immune-mediated nature of inflammatory bowel disease, the role of histamine and its receptors in the gut may be significant. This paper has been prepared to provide a schematic of the most important and possible molecular signaling pathways related to histamine and its receptors and to assess their relevance for the development of therapeutic approaches.

Is the microbiome the cause of irritable bowel syndrome and inflammatory bowel disease? Lessons to consider from odontology

BACKGROUND

A substantial amount of research is pointing to the disrupted microbiome and dysfunctional host-microbiome interaction as potential causes of Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). The true cause of the diseases is still not fully elucidated, and the various treatments used are not truly effective in the long run, especially for IBD, since a true cure is not known to exist. Treatment failure and surgery are common for IBD, many times leading to a perceived lower quality of life, not to mention the enormous cost for society for treatment up until that point and after. Although it is clear that the microbiome has a major role in the disease, it seems the majority of the research and treatments are still focused on treating and understanding the inflammation and not the primary cause of the inflammation in the first place. This was also the case for many decades in the search for the cause of periodontitis (PD) and gingivitis (GV), a destructive and non-destructive inflammatory disorder, respectively, the first resulting in loss of tissue supporting the teeth. There was much uncertainty and confusion until it was fully established that the microbiome was the cause. PD treatments primarily nowadays reflect the cause, i.e. the removal of microbes. There is no doubt, however, that the inflammatory pathways are important in both diseases and the purpose of this text is not to dispute this in respect to gastrointestinal disorders too. However, a different view on inflammation and associated disorders is explored to explain the nature of extraintestinal manifestations.

PURPOSE

The aim of this report is not to systematically fully review the literature to try to strengthen causality, as there are many reviews that explore the microbial aspects of IBS and IBD. Instead, the objective is to above all reflect on what has been learned in the field of odontology/stomatology and discuss relevant gastrointestinal research in order to propose tentative hypotheses and questions regarding IBS and IBD aetiology. Perhaps it could help soften the confusion regarding the microbial aetiology and dysbiosis concept, while guiding future research and treatments, primarily regarding microbial transplants, antibiotics, and diet.

Diamine Oxidase as a Therapeutic Enzyme: Study of Germination from Vegetal Sources and Investigation of the Presence of β-N-Oxalyl-L-α,β-diaminopropionic Acid (β-ODAP) Using LC-MS/MS

Vegetal diamine oxidase (vDAO), an enzyme proposed to relieve symptoms of histaminosis, shows better reactivity with histamine and aliphatic diamines, as well as higher enzymatic activity than DAO of animal origin. The objective of this study was to evaluate the enzyme activity of vDAO from germinating grains from Lathyrus sativus (grass pea) and Pisum sativum (pea), and to verify the presence of a neurotoxin, β-N-Oxalyl-L-α,β-diaminopropionic acid (β-ODAP), in the crude extract obtained from their seedlings. A targeted liquid chromatography-multiple-reaction monitoring mass spectrometry method was developed and used to quantify β-ODAP in the analysed extracts. An optimized sample preparation procedure, involving protein precipitation with acetonitrile followed by mixed-anion exchange solid-phase extraction, allowed for high sensitivity and good peak shape for β-ODAP detection. The Lathyrus sativus extract exhibited the highest vDAO enzyme activity of the extracts, followed by the extract from pea cultivar Amarillo from the Crop Development Centre (CDC). The results have also shown that even though β-ODAP was present in the crude extract from L. sativus, its content was far below the toxicity threshold (300 mg of β-ODAP/kg body/day). CDC Amarillo showed 5000-fold less β-ODAP than the undialysed L. sativus extract. It was concluded that both species can be considered as convenient sources of vDAO for potential therapeutic use.

Loss of apical sodium bile acid transporter alters bile acid circulation and reduces biliary damage in cholangitis

Primary sclerosing cholangitis (PSC) is characterized by increased ductular reaction (DR), liver fibrosis, hepatic total bile acid (TBA) levels, and mast cell (MC) infiltration. Apical sodium BA transporter (ASBT) expression increases in cholestasis, and ileal inhibition reduces PSC phenotypes. FVB/NJ and multidrug-resistant 2 knockout (Mdr2-/-) mice were treated with control or ASBT Vivo-Morpholino (VM). We measured 1) ASBT expression and MC presence in liver/ileum; 2) liver damage/DR; 3) hepatic fibrosis/inflammation; 4) biliary inflammation/histamine serum content; and 5) gut barrier integrity/hepatic bacterial translocation. TBA/BA composition was measured in cholangiocyte/hepatocyte supernatants, intestine, liver, serum, and feces. Shotgun analysis was performed to ascertain microbiome changes. In vitro, cholangiocytes were treated with BAs ± ASBT VM, and histamine content and farnesoid X receptor (FXR) signaling were determined. Treated cholangiocytes were cocultured with MCs, and FXR signaling, inflammation, and MC activation were measured. Human patients were evaluated for ASBT/MC expression and histamine/TBA content in bile. Control patient- and PSC patient-derived three-dimensional (3-D) organoids were generated; ASBT, chymase, histamine, and fibroblast growth factor-19 (FGF19) were evaluated. ASBT VM in Mdr2-/- mice decreased 1) biliary ASBT expression, 2) PSC phenotypes, 3) hepatic TBA, and 4) gut barrier integrity compared with control. We found alterations between wild-type (WT) and Mdr2-/- mouse microbiome, and ASBT/MC and bile histamine content increased in cholestatic patients. BA-stimulated cholangiocytes increased MC activation/FXR signaling via ASBT, and human PSC-derived 3-D organoids secrete histamine/FGF19. Inhibition of hepatic ASBT ameliorates cholestatic phenotypes by reducing cholehepatic BA signaling, biliary inflammation, and histamine levels. ASBT regulation of hepatic BA signaling offers a therapeutic avenue for PSC.NEW & NOTEWORTHY We evaluated knockdown of the apical sodium bile acid transporter (ASBT) using Vivo-Morpholino in Mdr2KO mice. ASBT inhibition decreases primary sclerosing cholangitis (PSC) pathogenesis by reducing hepatic mast cell infiltration, altering bile acid species/cholehepatic shunt, and regulating gut inflammation/dysbiosis. Since a large cohort of PSC patients present with IBD, this study is clinically important. We validated findings in human PSC and PSC-IBD along with studies in novel human 3-D organoids formed from human PSC livers.

Advances in the Clinical Application of Histamine and Diamine Oxidase (DAO) Activity: A Review

The serum level of diamine oxidase (DAO) reflects the integrity and maturation of the small intestinal mucosa. This measure is important in diagnosing various diseases, including chronic urticaria tachyphylaxis, multiple organ dysfunction syndrome, preterm abortion, and migraine. This review aimed to summarize the findings of previous studies on the changes in DAO levels in diverse diseases and the application of this enzyme in the clinical setting, as well as the roles of this enzyme under physiological and pathological conditions. The advances in the mechanism and clinical application of DAO presented in this review will contribute to a better understanding of this enzyme and open up new and broader perspectives for future basic research and clinical applications.

Improvement of digestive symptoms in fibromyalgia patients following a diet modification according to histamine release test - an observational study

Introduction

There is growing interest in the relationship between fibromyalgia and processes related to food, such as food intolerances. In fact, different associations have been described between the control of dietary habits and the improvement of the different symptoms of fibromyalgia.

Material and methods

We collected the results of applying a specific test of histamine release related to the diet of patients with fibromyalgia, and evaluated the changes in terms of the symptoms usually described by the patients. A total of 84 patients who met the established criteria were recruited; 40 of them underwent the exclusion diet for a period of 6 months, while the remaining ones continued with their usual dietary habits. All patients were instructed not to modify any other parameter during the study, such as medication, exercise, or other complementary treatments. The parameters studied were as follows: the Fibromyalgia Impact Questionnaire (FIQ), the Gastrointestinal Symptoms Rating Scale (GSRS), the pain Visual Analogue Scale (VAS), as well as the patients' body weight was controlled.

Results

There was a significant improvement (p < 0.05) in the group of patients who underwent the exclusion diet in assesment by GSRS and in total in total body weight. There were no differences compared to the rest of the patients in terms of VAS and FIQ.

Conclusions

Diet modification in patients with fibromyalgia by specific histamine relase test improves certain clinical parameters related to the symptoms of the digestive sphere, compared to the control group. Our work opens a possible way of non-pharmacological treatment to improve some symptoms of this very prevalent disease.

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.

Intestinal Dysbiosis in Patients with Histamine Intolerance

An underlying cause of histamine intolerance is diamine oxidase (DAO) deficiency, which leads to defective homeostasis and a higher systemic absorption of histamine. Impaired DAO activity may have a genetic, pharmacological or pathological origin. A recent proposal also suggests it can arise from an alteration in the gut microbiota, although only one study has explored this hypothesis to date. A greater abundance of histamine-secreting bacteria in the gut could lead to the development of histamine intolerance. Thus, the aim of this study was to characterize the composition of the intestinal microbiota of patients with histamine intolerance symptoms and compare it with that of healthy individuals. The study was performed by sequencing bacterial 16S rRNA genes (V3-V4 region) and analyzing the data using the EzBioCloud Database. Dysbiosis of the gut microbiota was observed in the histamine intolerance group who, in comparison with the healthy individuals, had a significantly lower proportion of Prevotellaceae, Ruminococcus, Faecalibacterium and Faecablibacterium prausnitzii, which are bacteria related to gut health. They also had a significantly higher abundance of histamine-secreting bacteria, including the genera Staphylococcus and Proteus, several unidentified genera belonging to the family Enterobacteriaceae and the species Clostridium perfringens and Enterococcus faecalis. A greater abundance of histaminogenic bacteria would favor the accumulation of high levels of histamine in the gut, its subsequent absorption in plasma and the appearance of adverse effects, even in individuals without DAO deficiency.

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.

Histamine Intolerance-A Kind of Pseudoallergic Reaction

Histamine intolerance (HIT) is a common disorder associated with impaired histamine metabolism. Notwithstanding, it is often misdiagnosed as other diseases because of its lack of specific clinical manifestations. HIT did not gain traction until the early 21st century. In this review, we will focus on the latest research and elaborate on the clinical manifestations of HIT, including its manifestations in special populations such as atopic dermatitis (AD) and chronic urticaria (CU), as well as the latest understanding of its etiology and pathogenesis. In addition, we will explore the latest treatment strategies for HIT and the treatment of specific cases.

Food allergy and hypersensitivity reactions in children and adults-A review

Adverse reactions after food intake are commonly reported and a cause of concern and anxiety that can lead to a very strict diet. The severity of the reaction can vary depending on the type of food and mechanism, and it is not always easy to disentangle different hypersensitivity diagnoses, which sometimes can exist simultaneously. After a carefully taken medical history, hypersensitivity to food can often be ruled out or suspected. The most common type of allergic reaction is immunoglobulin E (IgE)-mediated food allergy (prevalence 5-10%). Symptoms vary from mild itching, stomach pain, and rash to severe anaphylaxis. The definition of IgE-mediated food allergy is allergic symptoms combined with specific IgE-antibodies, and therefore only IgE-antibodies to suspected allergens should be analyzed. Nowadays, methods of molecular allergology can help with the diagnostic process. The most common allergens are milk and egg in infants, peanut and tree nuts in children, and fish and shellfish in adults. In young children, milk/egg allergy has a good chance to remit, making it important to follow up and reintroduce the food when possible. Other diseases triggered by food are non-IgE-mediated food allergy, for example, eosinophilic esophagitis, celiac disease, food protein-induced enterocolitis syndrome, and hypersensitivity to milk and biogenic amines. Some of the food hypersensitivities dominate in childhood, others are more common in adults. Interesting studies are ongoing regarding the possibilities of treating food hypersensitivity, such as through oral immunotherapy. The purpose of this review was to provide an overview of the most common types of food hypersensitivity reactions.

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.

Role of the nuclear receptor subfamily 4a in mast cells in the development of irritable bowel syndrome

The activation of mast cells (MCs) and mediator release are closely related to the pathophysiology of irritable bowel syndrome (IBS). However, the exact underlying mechanisms are still not completely understood. The nuclear receptor subfamily 4a (Nr4a) is a family of orphan nuclear receptors implicated in regulating MC activation, degranulation, cytokine/chemokine synthesis and release. Acute and chronic stress trigger hypothalamic–pituitaryadrenal axis (HPA) activation to induce the release of corticotropin-releasing hormone (CRH), resulting in MC activation and induction of the Nr4a family. Our newest data showed that Nr4a members were specially over-expressed in colonic MCs of the chronic water-avoidance stress (WAS)-induced visceral hyperalgesia mice, suggesting that Nr4a members might be involved in the pathophysiology of visceral hypersensitivity. In this review, we highlight the present knowledge on roles of Nr4a members in the activation of MCs and the pathophysiology of IBS, and discuss signaling pathways that modulate the activation of Nr4a family members. We propose that a better understanding of Nr4a members and their modulators may facilitate the development of more selective and effective therapies to treat IBS patients.

Exploring functional metabolites in preterm infants

AIM

Metabolomics is the study of small molecules that represent the functional end points of cellular reactions that can impact health. Necrotising enterocolitis (NEC) and late onset sepsis (LOS) are the main cause of death in preterm infants surviving the initial days of life.

METHODS

This review will explore and summarise the current literature exploring metabolomics in preterm infants.

RESULTS

There are a relatively limited number of studies investigating metabolomics in preterm infants with NEC and/or LOS and matched controls. Nonetheless, it is evident across longitudinally age-related metabolomic studies that there are significant changes in metabolite profiles post-partum and over the first year of life. Existing studies have reported associations between the metabolite profiles of serum, urine and stool in health and disease in preterm infants. Although some studies have found selected metabolites are associated with disease, the specific metabolites vary from study to study, and larger studies are required. Excitingly, recent work has also begun to untangle how microbially produced metabolites can impact immunoregulation of the infant.

CONCLUSION

Metabolic exploration is an emerging research area with huge potential for developing novel biomarkers and better understanding disease processes in preterm infants.

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.