A case of atopic cough with aphonia showed a prominent response to a histamine H1 receptor antagonist

A 33-year-old woman admitted to our hospital for further examination of severe non-productive cough lasting for about two months. Her symptom did not ameliorate by treatments including long acting β2 agonists. She had a medical history of drug allergy to non-steroidal anti-inflammatory drugs. At the initial visit, she could not speak at all and communicated with us in writing. Chest auscultation revealed no wheezes, rhonchi and other crackles. Laboratory findings showed a mild eosinophilia with normal total and specific serum immunoglobulin E. The results of an electrocardiogram, a chest X-ray and a chest CT were unremarkable. A fractional exhaled nitric oxide value was within normal limit. Based on these observations, a diagnosis of atopic cough (AC) was suspected, and we started treatment with a histamine H1 receptor antagonist (H1-RA). She had become able to speak again in association with complete disappearance of cough by eight-weeks after treatment initiation, and her symptoms did not recur even after cessation of treatment. By the confirmation of remarkable clinical improvement in response to a H1-RA, a diagnosis of AC was made. To the best of our knowledge, this is the first report of an AC patient who presented severe cough with aphonia. J. Med. Invest. 70 : 281-284, February, 2023.

Selective inhibitors for phosphodiesterase 3 and 4 in antigen-induced increase of cough reflex sensitivity in guinea pigs

Effects of the selective phosphodiesterase 3 (PDE3) inhibitor olprinone and the selective PDE4 inhibitor SB207499 were investigated on antigen-induced increase of cough reflex sensitivity and normal cough response to capsaicin in guinea pigs. Number of coughs elicited by inhalation of capsaicin (10(-8), 10(-6) and 10(-4)M) was counted 24h after an antigen challenge in actively sensitized guinea pigs, and then bronchoalveolar lavage (BAL) was performed. Olprinone (1 or 10mg/kg) or SB207499 (1 or 10mg/kg) was given twice intraperitoneally: One hour after the antigen challenge and 1h before the capsaicin provocation. SB207499, but not olprinone, significantly reduced both antigen-induced increase of cough response to inhaled capsaicin in sensitized animals and normal cough response in non-sensitized animals. SB207499, but not olprinone, also reduced the antigen-induced BAL eosinophilia. PDE4 inhibitors may be useful in treating cough associated with airway allergy via inhibiting both allergic airway inflammation and the common pathway of cough reflex.

Atopic cough-like cough hypersensitivity caused by active sensitization with protein fraction of Aspergillus restrictus strain A-17

We examined the sensitivity of the cough reflex to inhaled citric acid in guinea pigs that had been actively sensitized with the protein fraction of Aspergillus restrictus strain A-17. The number of coughs elicited by an aerosol of 5% citric acid was significantly increased in the sensitized group compared to the non-sensitized group. The number of citric-acid-induced coughs in sensitized guinea pigs was dose-dependently and significantly reduced to the level in non-sensitized guinea pigs when animals were pretreated with fexofenadine, a selective histamine H1 receptor antagonist, 60min before citric acid inhalation. The bronchial responsiveness to inhaled methacholine or histamine in the sensitized group was not significantly heightened compared to the non-sensitized group. These results suggest that active sensitization with the protein fraction of A. restrictus by itself, that is without subsequent allergen challenge, enhances the excitability of cough receptors to tussive stimuli, and the physiologic features of this animal model are consistent with those of atopic cough.

Comparison of cough reflex sensitivity after an inhaled antigen challenge between actively and passively sensitized guinea pigs

Background

Late asthmatic response is observed following antigen challenge in actively, but not passively, sensitized guinea pigs. Although cough reflex sensitivity is increased after antigen challenge in actively sensitized guinea pigs, it is unknown whether the antigen-induced increase in cough reflex sensitivity develops in passively sensitized animals. The aim of this study was to compare the cough reflex sensitivity to inhaled capsaicin after an inhaled antigen challenge between actively and passively sensitized guinea pigs.

Methods

Measurement of number of coughs elicited by increasing concentrations of capsaicin (10^-6 and 10^-4 M) and bronchial responsiveness to ascending concentrations of methacholine, and analysis of bronchoalveolar lavage fluid (BALF) were separately performed 24 h after an antigen challenge in actively and passively sensitized guinea pigs.

Results

Percentage of eosinophils in BALF and bronchial responsiveness to methacholine were increased 24 h after the antigen challenge in both actively and passively sensitized animals compared with saline-challenged actively and passively sensitized animals, respectively. Absolute number of eosinophils in BALF from actively sensitized and antigen-challenged guinea pigs was significantly greater than that from passively sensitized and antigen-challenged animals. Cough response to capsaicin and concentration of substance P in BALF were increased 24 h after the antigen challenge in actively sensitized guinea pigs, but not in passively sensitized guinea pigs. Bronchial responsiveness, cough reflex sensitivity and substance P concentration and total cells in BALF were increased in actively sensitized and saline challenged guinea pigs compared with passively sensitized and saline challenged animals.

Conclusion

The results suggest that active sensitization per se increases cough reflex sensitivity accompanied by increased inflammatory cells and substance P level in BALF, and antigen challenge further increases them, while simple IgE- and/or IgG-mediated allergic reaction per se or the low intensity of eosinophil infiltration in the airway itself may not affect cough reflex sensitivity in guinea pigs.