Urinary N tau-methylimidazole acetic acid excretion in respiratory disease

Population histamine burden assessed using wastewater-based epidemiology: The association of 1,4‑methylimidazole acetic acid and fexofenadine

Systematic sampling and analysis of wastewater has become an important tool for monitoring consumption of drugs and other substances, and has been proposed as a method to evaluate aspects of population health using endogenous biomarkers. 1,4‑methylimidazoleacetic acid (MIAA) is an endogenous biomarker and metabolite of histamine turnover. Its urinary excretion is elevated in conditions such as mastocytosis, hay fever, hives, food allergies and anaphylaxis. The aim of this study was to develop and apply methods for MIAA in wastewater and compare its occurrence with antihistamine use in wastewater. Consecutive daily samples were collected from seven catchments serving populations from 3000 to 2 million and covering rural and urban communities during the 2016 Census in Australia. MIAA and the antihistamines (ranitidine, fexofenadine, cetirizine) were quantified consistently. Per capita excretion of MIAA (mg/d/capita) estimated from the WW concentrations were consistent with findings from previous clinical studies. We found significant positive correlations between loads of MIAA and fexofenadine (R² = 0.68, p < 0.0001) and cetirizine (R² = 0.25, p = 0.03) across the various catchments. Sewer reactor experiments on the degradation of MIAA and the antihistamines found that fexofenadine is stable for at least 24 h while MIAA, ranitidine and cetirizine are subject to degradation, and this should be considered in interpretations. To the best of our knowledge, this study is the first wastewater study to introduce and monitor an endogenous metabolite of histamine, and the first study to monitor and relate proxies of disease and treatment of disease.

Urinary histamine metabolite elevations during experimental influenza infection

BACKGROUND

Although histamine is hypothesized to mediate symptoms induced by viral upper respiratory infections, elevations of this mediator have not been observed in nasal lavage fluids recovered from patients with viral upper respiratory infections.

OBJECTIVE

The purpose of this study was to use a novel method to determine whether histamine is released during experimental influenza A infection.

METHODS

Healthy adults (n = 15) were cloistered and inoculated intranasally with influenza A virus, and monitored for infection and illness. Daily morning void urines were collected and assayed for histamine and its metabolites by gas chromatography-mass spectrometry. Total histamine was calculated for each urine specimen by summing the assayed values of histamine and its metabolites.

RESULTS

All subjects were infected and developed illness. ANOVA documented a significant effect of study day (viral infection) on urinary levels of total histamine (P < 0.02). Pairwise analysis showed a significant elevation 2 days after inoculation.

CONCLUSIONS

These results provide the first direct evidence that histamine is released in vivo during infection with a virus that causes cold/flu symptoms.

Diurnal variation of urinary histamine and 1-methylhistamine excretion in healthy children

In order to establish a noninvasive method of monitoring immediate hypersensitivity reactions in children, we studied the diurnal variation of urinary histamine and 1-methylhistamine excretion and the influence of food intake in a group of 14 healthy nonatopic children (aged 2-16 years). Histamine and 1-methylhistamine in spontaneous urine samples were determined by radioimmunoassay. Mean variation of 2-h intervals was much higher for urinary histamine than for 1-methylhistamine (45% of base-line level versus 24%). There was no circadian rhythm or influence of food intake. The short half-life of histamine released into blood circulation may be the main reason for the higher variation of histamine excretion. In children, urinary 1-methylhistamine is less influenced by diurnal variation and is therefore more suited to monitor immediate hypersensitivity reactions than urinary histamine itself.