Eight International London Cough Symposium 2014: Cough hypersensitivity syndrome as the basis for chronic cough

Clinical characteristics and drug utilisation patterns in patients with chronic cough: a retrospective cohort study using a Japanese claims database

BACKGROUND

Although unmet medical needs for better care of patients with chronic cough exist in Japan, epidemiological information about these patients and their treatments is very limited.

OBJECTIVES

To describe patient characteristics, underlying cough-related diseases and drug utilisation patterns in patients with chronic cough, and their changes over time.

METHODS

This large retrospective claims database study enrolled subjects with chronic cough, identified either by a specific diagnostic cough code for chronic cough (Population 1) or by multiple cough-related diagnostic codes spanning > 8 weeks (Population 2). Within Population 2, patients with each of the three most frequent diagnostic cough codes were analysed as subgroups. Patient characteristics, underlying cough-related diseases and utilisation patterns for drugs used for cough were documented at the index date, during the 6-month pre-index period and during the 12-month post-index period.

RESULTS

6,038 subjects were enrolled in the cohort (Population 1: N = 3,500; Population 2: N = 2,538). The mean age was 43.7 ± 12.2 years and 61.8% were women. The largest cough diagnosis subgroups in Population 2 were 'other coughs' (N = 1,444), 'cough-variant asthma' (N = 1,026) and 'atopic/allergic cough' (N = 105). At the index date, the most frequent underlying cough-related diseases were allergic rhinitis/nasal inflammation (N = 3,132; 51.9%), asthma (N = 2,517; 41.7%) and gastro-esophageal reflux disease (N = 829; 13.7%). At the index date, 4,860 participants (80.5%) were prescribed at least one cough-related treatment. 194 participants (4.0% of medication users) were prescribed central antitussives alone, principally in Population 1, and 2,331 (48.0%) were prescribed expectorants. Other frequently prescribed medications were antiallergic drugs (N = 2,588; 53.3%), antimicrobials (N = 1,627; 34.4%) and inhaled corticosteroids with long-acting beta-agonists (N = 1,404; 28.9%). Over time, cough diagnoses tended to be lost, with only 470 participants in Population 1 retaining a diagnostic code for chronic cough one year later. The frequency of underlying cough-related diseases was stable over time.

CONCLUSIONS

Patients in this cohort with chronic cough are most frequently identified by a diagnostic cough code for chronic cough, followed by codes for other coughs, cough-variant asthma and atopic cough. Chronic cough frequently presents with an underlying cough-related disease, most frequently allergic rhinitis/nasal inflammation, asthma or GERD. Medication prescription for the underlying cough-related diseases was generally appropriate.

Pathogenesis and treatment principles ocular damage by self-defense gas weapons

The article presents the pathogenetic mechanisms of eye damage by gas self-defense weapons in detail. We discuss the mechanisms of eye damage and structural changes of the tissues after gas-trauma. The causes of these changes and the main clinical manifestations accompanying them are analyzed. We analyzed the factors, influencing the development of dystrophic changes of the ocular surface in detail. The information on various techniques for self-assistance, mutual aid and earlier specific treatment of this injury was summarized. An aqueous solution of pediphene substance promising for use is considered, which has a number of pharmacological properties that fundamentally affect the pathogenetic mechanisms of gas-weapon trauma. Its effectiveness was shown in the experiment in comparison with the control group without treatment and the group using the combined drug-dexamethasone in combination with an antibiotic.

Investigating Potential TRPV1 Positive Feedback to Explain TRPV1 Upregulation in Airway Disease States

OBJECTIVE

The airway epithelium is a potential source of pathophysiology through activation of transient potential receptor vallinoid type 1 (TRPV1) channel. A positive feedback cycle caused by TRPV1 activity is hypothesised to induce upregulation and production of inflammatory cytokines, leading to exacerbations of chronic airway diseases. These cytokine and protein regulation effects were investigated in this study.

METHODS

Healthy (BEAS-2B) and cancer-derived (Calu-3) airway epithelial cell lines were assessed for changes to TRPV1 protein expression and mRNA expression following exposure to capsaicin (5 µM to 50 µM), and TRPV1 modulators including heat (43 °C), and hydrochloric acid (pH 3.4 to pH 6.4). Cytotoxicity was measured to determine the working concentration ranges of treatment. Subsequent bronchoconstriction by TRPV1 activation with capsaicin was measured on guinea pig airway tissue to confirm locally mediated activity without the action of known neuronal inputs.

RESULTS

TRPV1 protein expression was not different for all capsaicin, acidity, and heat exposures (P > 0.05), and was replicated in mRNA protein expression (P > 0.05). IL-6 and IL-8 expression were lower in BEAS-2B and Calu-3 cell lines exposed with acidity and heat (P < 0.05), but not consistently with capsaicin exposure, with potential cytotoxic effects possible.

CONCLUSIONS

TRPV1 expression was present in airway epithelial cells but its expression was not changed after activation by TRPV1 activators. Thus, it was not apparent the reason for reported TRPV1 upregulation in patients with airway disease states. More complex mechanisms are likely involved and will require further investigation.

Laryngeal hypersensitivity and abnormal cough response during mannitol bronchoprovocation challenge

BACKGROUND AND OBJECTIVE

Inhalational challenge with dry mannitol powder may potentially induce cough by two mechanisms: airway bronchoconstriction or laryngeal irritation. This prospective observational study investigated laryngeal and bronchial components of cough induced by mannitol challenge.

METHODS

We recruited consecutive patients referred for clinical mannitol challenge. The Newcastle Laryngeal Hypersensitivity Questionnaire (LHQ) was administered. Throughout testing, coughs were audio-recorded to derive a cough frequency index per time and dose of mannitol. Relationships between cough indices, laryngeal hypersensitivity and bronchial hyperresponsiveness (BHR) were examined. Participants were classified by cough characteristics with k-means cluster analysis.

RESULTS

Of 90 patients who underwent challenge, 83 completed both the questionnaire and challenge. Cough frequency was greater in patients with abnormal laryngeal hypersensitivity (p = 0.042), but not in those with BHR. There was a moderate negative correlation between coughs per minute and laryngeal hypersensitivity score (r = -0.315, p = 0.004), with lower LHQ scores being abnormal. Cluster analysis identified an older, female-predominant cluster with higher cough frequency and laryngeal hypersensitivity, and a younger, gender-balanced cluster with lower cough frequency and normal laryngeal sensitivity.

CONCLUSION

Cough frequency during mannitol challenge in our cohort reflected laryngeal hypersensitivity rather than BHR. Laryngeal hypersensitivity was more often present among older female patients. With the incorporation of cough indices, mannitol challenge may be useful to test for laryngeal hypersensitivity as well as BHR.

Modulation of protective reflex cough by acute immune driven inflammation of lower airways in anesthetized rabbits

Chronic irritating cough in patients with allergic disorders may reflect behavioral or reflex response that is inappropriately matched to the stimulus present in the respiratory tract. Such dysregulated response is likely caused by sensory nerve damage driven by allergic mediators leading to cough hypersensitivity. Some indirect findings suggest that even acid-sensitive, capsaicin-insensitive A-δ fibers called “cough receptors” that are likely responsible for protective reflex cough may be modulated through immune driven inflammation. The aim of this study was to find out whether protective reflex cough is altered during acute allergic airway inflammation in rabbits sensitized to ovalbumin. In order to evaluate the effect of such inflammation exclusively on protective reflex cough, C-fiber mediated cough was silenced using general anesthesia. Cough provocation using citric acid inhalation and mechanical stimulation of trachea was realized in 16 ovalbumin (OVA) sensitized, anesthetized and tracheotomised rabbits 24h after OVA (OVA group, n = 9) or saline challenge (control group, n = 7). Number of coughs provoked by citric acid inhalation did not differ between OVA and control group (12,2 ±6,1 vs. 17,9 ± 6,9; p = 0.5). Allergic airway inflammation induced significant modulation of cough threshold (CT) to mechanical stimulus. Mechanically induced cough reflex in OVA group was either up-regulated (subgroup named “responders” CT: 50 msec (50–50); n = 5 p = 0.003) or down-regulated (subgroup named “non responders”, CT: 1200 msec (1200–1200); n = 4 p = 0.001) when compared to control group (CT: 150 msec (75–525)). These results advocate that allergen may induce longer lasting changes of reflex cough pathway, leading to its up- or down-regulation. These findings may be of interest as they suggest that effective therapies for chronic cough in allergic patients should target sensitized component of both, reflex and behavioral cough.

Is TRPA1 Burning Down TRPV1 as Druggable Target for the Treatment of Chronic Pain?

Over the last decades, a great array of molecular mediators have been identified as potential targets for the treatment of chronic pain. Among these mediators, transient receptor potential (TRP) channel superfamily members have been thoroughly studied. Namely, the nonselective cationic channel, transient receptor potential ankyrin subtype 1 (TRPA1), has been described as a chemical nocisensor involved in noxious cold and mechanical sensation and as rivalling TRPV1, which traditionally has been considered as the most important TRP channel involved in nociceptive transduction. However, few TRPA1-related drugs have succeeded in clinical trials. In the present review, we attempt to discuss the latest data on the topic and future directions for pharmacological intervention.

Advances in mechanisms and management of chronic cough: The Ninth London International Cough Symposium 2016

At the Ninth London International Cough Symposium held in June 2016, advances in chronic cough were presented. Chronic cough has been labelled as a cough hypersensitivity syndrome (CHS) with neuroinflammatory mechanisms likely to be the underlying mechanisms. The concept is that there is a stage of peripheral sensitisation induced by inflammatory factors setting up the scene for a central component that can be visualised by functional magnetic resonance imaging. There has also been progress in assessing CHS patients in the clinic in terms of measuring cough, with an increasing interest in assessing different types of cough associated with respiratory diseases such as asthma, COPD, bronchiectasis and pulmonary fibrosis. There is an emerging area of new antitussives in the form of neuromodulators. These advances have been paralleled by improvements in the management of patients with chronic cough. However, more work is needed but the future looks promising.

Evidence-based Evaluation and Management of Chronic Cough

Chronic cough is common and has a significant impact on the wellbeing of patients and the use and cost of health care services. Traditionally the approach to chronic cough in patients who are nonsmokers and are not taking an angiotensin-converting enzyme inhibitor has focused on the diagnosis and management of the upper airway cough syndrome, asthma, and reflux disease. The evaluation of patients with chronic cough frequently involves trials of empiric therapy for these 3 conditions. Chronic cough may be perpetuated by abnormalities of the cough reflex and sensitization of its afferent and central components.

Tear gas: an epidemiological and mechanistic reassessment

Deployments of tear gas and pepper spray have rapidly increased worldwide. Large amounts of tear gas have been used in densely populated cities, including Cairo, Istanbul, Rio de Janeiro, Manama (Bahrain), and Hong Kong. In the United States, tear gas was used extensively during recent riots in Ferguson, Missouri. Whereas tear gas deployment systems have rapidly improved-with aerial drone systems tested and requested by law enforcement-epidemiological and mechanistic research have lagged behind and have received little attention. Case studies and recent epidemiological studies revealed that tear gas agents can cause lung, cutaneous, and ocular injuries, with individuals affected by chronic morbidities at high risk for complications. Mechanistic studies identified the ion channels TRPV1 and TRPA1 as targets of capsaicin in pepper spray, and of the tear gas agents chloroacetophenone, CS, and CR. TRPV1 and TRPA1 localize to pain-sensing peripheral sensory neurons and have been linked to acute and chronic pain, cough, asthma, lung injury, dermatitis, itch, and neurodegeneration. In animal models, transient receptor potential inhibitors show promising effects as potential countermeasures against tear gas injuries. On the basis of the available data, a reassessment of the health risks of tear gas exposures in the civilian population is advised, and development of new countermeasures is proposed.