Histamine, histamine intoxication and intolerance

Excessive accumulation of histamine in the body leads to miscellaneous symptoms mediated by its bond to corresponding receptors (H1-H4). Increased concentration of histamine in blood can occur in healthy individuals after ingestion of foods with high contents of histamine, leading to histamine intoxication. In individuals with histamine intolerance (HIT) ingestion of food with normal contents of histamine causes histamine-mediated symptoms. HIT is a pathological process, in which the enzymatic activity of histamine-degrading enzymes is decreased or inhibited and they are insufficient to inactivate histamine from food and to prevent its passage to blood-stream. Diagnosis of HIT is difficult. Multi-faced, non-specific clinical symptoms provoked by certain kinds of foods, beverages and drugs are often attributed to different diseases, such as allergy and food intolerance, mastocytosis, psychosomatic diseases, anorexia nervosa or adverse drug reactions. Correct diagnosis of HIT followed by therapy based on histamine-free diet and supplementation of diamine oxidase can improve patient's quality of life

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Histamine, histamine intoxication and intolerance.

Excessive accumulation of histamine in the body leads to miscellaneous symptoms mediated by its bond to corresponding receptors (H1-H4). Increased concentration of histamine in blood can occur in healthy individuals after ingestion of foods with high contents of histamine, leading to histamine intoxication. In individuals with histamine intolerance (HIT) ingestion of food with normal contents of histamine causes histamine-mediated symptoms. HIT is a pathological process, in which the enzymatic activity of histamine-degrading enzymes is decreased or inhibited and they are insufficient to inactivate histamine from food and to prevent its passage to blood-stream. Diagnosis of HIT is difficult. Multi-faced, non-specific clinical symptoms provoked by certain kinds of foods, beverages and drugs are often attributed to different diseases, such as allergy and food intolerance, mastocytosis, psychosomatic diseases, anorexia nervosa or adverse drug reactions. Correct diagnosis of HIT followed by therapy based on histamine-free diet and supplementation of diamine oxidase can improve patient's quality of life.

The effect of selective antagonist of H4 receptor JNJ7777120 on nasal symptoms, cough, airway reactivity and inflammation in guinea pigs.

The efficacy of H4R antagonist JNJ7777120 on nasal symptoms, cough, airway resistance (Raw), inflammatory cell count in bronchoalveolar lavage (BAL) and blood in ovalbumin (OVA) induced allergic rhinitis (AR) was studied in guinea pigs. Animals (n=8) were sensitized by i.p. OVA and were repeatedly challenged with nasal OVA to induce rhinitis, seven animals were not sensitized. Animals were pre-treated with JNJ7777120 2.5 and 5mg/kg i.p. 30 min prior OVA. Cough was induced by inhalation of citric acid, Raw was measured in vivo by Pennock's method as baseline, during AR and after JNJ7777120 treatment. Leucocyte count in BAL and blood was analyzed. JNJ7777120 (5mg/kg) significantly suppressed nasal symptoms and the number of coughs. This compound significantly inhibited airway reactivity to histamine, but not methacholine. Pre-treatment with JNJ7777120 5mg/kg did not influence significantly the leucocyte count in BAL and blood except for a significant decrease in monocyte count in blood compared to the control group (p<0.05). We conclude that the antitussive action of JNJ7777120 is peripheral. The primary effect of the compound is anti-inflammatory, and the suppression of cough is a consequence of reduced airway inflammation.

The effects of nasal irritant induced responses on breathing and cough in anaesthetized and conscious animal models.

There is little evidence to support the down-regulation of coughing from the nose. The cough response to citric acid (CA) was studied in anesthetized and conscious guinea pigs after nasal pretreatment with saline, 1% DMSO, allylisothiocyanate (TRPA1 agonist) and allylisothiocyanate +AP-18 (TRPA1 antagonist). Cough was induced by adding citric acid (CA) to the tracheal perfusion in anaesthetized animals, or by inhaling 0.4M CA in conscious animals. The cough response was counted from the dose response curves, airflow traces and cough sound analysis. In conscious animals, nasal allylisothiocyanate induced reproducible, dose dependent nasal symptoms and a significant drop in respiratory rate. Cough induced by CA was suppressed after nasal allylisothiocyanate (p<0.05), and this effect was prevented by AP-18 (1mM). In anaesthetized animals, nasal allylisothiocyanate induced a significant drop in respiratory rate. Cough induced subsequently by CA was suppressed when compared to baseline and vehicle responses (p<0.05). The reasons for the suppression of CA induced cough by TRPA1 agonist applied to the nose are not clear and remain to be elucidated.

[Histamine intolerance]. / Histamínová intolerancia.

Histamine intolerance (HIT) is a pathological process that results from a disbalance between levels of released histamine and the ability of the body to metabolize it. Accumulated histamine leads to the onset of "histamine mediated" reactions which are usually excessive and decrease quality of life. Although we have a lot of knowledge about histamine intolerance, HIT is still vastly underestimated, because it manifests via the diversity of clinical symptoms, that are often misinterpreted by the patient and sometimes even by a physician. Clinical symptoms and their provocation by certain kinds of food, beverages and drugs are often attributed to the different diseases, such as food allergy and intolerance of sulfites, or other biogenic amines (eg. tyramine), mastocytosis, psychosomatic diseases or adverse drug reactions in general. Proper diagnosis of HIT followed by therapy based on histamine--free diet and supplementation of diaminooxidase can considerably improve patient's quality of life.