Cough and viruses in airways disease: mechanisms

Evolutionary principles for modifying pathogen virulence

Current methods for combatting infectious diseases are largely limited to the prevention of infection, enhancing host immunity (via vaccination), and administration of small molecules to slow the growth of or kill pathogens (e.g. antimicrobials). Beyond efforts to deter the rise of antimicrobial resistance, little consideration is given to pathogen evolution. Natural selection will favor different levels of virulence under different circumstances. Experimental studies and a wealth of theoretical work have identified many likely evolutionary determinants of virulence. Some of these, such as transmission dynamics, are amenable to modification by clinicians and public health practitioners. In this article, we provide a conceptual overview of virulence, followed by an analysis of modifiable evolutionary determinants of virulence including vaccinations, antibiotics, and transmission dynamics. Finally, we discuss both the importance and limitations of taking an evolutionary approach to reducing pathogen virulence.

Infections including SARS-CoV-2 as triggers for vocal cord dysfunction

Vocal cord dysfunction (VCD) is often under-recognized and/or misdiagnosed as asthma. Although post-viral syndrome has been suggested as a contributing factor in VCD, there is limited data on infection-associated VCD. The purpose of this study was to assess and describe the proportion of patients who were diagnosed with VCD who did and did not report infection preceding VCD diagnosis. Subjects age ≥ 12 years referred for VCD assessment at the time of provocation challenge-rhinolaryngoscopy were enrolled in this prospective study of triggers for VCD registry. Enrollment initiated September 2021. An investigator designed questionnaire of potential triggers for VCD including SARS-CoV-2 was administered with medical data collection using REDCap software platform. Characteristics of subjects with and without respiratory infection-associated VCD were analyzed using Chi-square test and Student’s t-test. Of the 54 subjects analyzed, 57.4% (N=31) reported infection-associated VCD symptoms with either 1) VCD onset following respiratory infection (N=18, 33.3%) or 2) VCD symptoms worsened following SARS-CoV-2 infection (N=13, 24.1%). Subjects with infection-associated and non-infection-associated VCD otherwise shared largely similar characteristics. There were more subjects being age greater than 40 years in the infection-associated group (p=0.027) and this group also reported more throat clearing (p=0.019). Our results suggest a role for infectious etiologies, including SARS-CoV-2, in triggering and/or worsening VCD. VCD should be considered in the differential diagnosis of protracted shortness of breath following SARS-CoV-2 and other respiratory infections.

Preventing upper respiratory tract infections with prophylactic nasal carrageenan: a feasibility study

Aim: To observe upper respiratory tract infection (URTI) symptoms, rhinovirus levels and compliance with daily carrageenan nasal spray. Methods: 102 adults were randomized to carrageenan or saline placebo three times daily for 8 weeks and URTI symptoms were recorded. A control group (n = 42) only recorded URTI symptoms. Participants collected nasal swabs when symptomatic. Results: Regular daily carrageenan prophylaxis resulted in consistent but nonsignificant reductions in URTI symptoms versus the placebo group. Saline placebo decreased and increased some cold symptoms compared with no treatment. Conclusion: Daily prophylactic administration of antiviral carrageenan may not significantly reduce URTI symptoms. Due to low compliance, use in a population with specific reasons to avoid URTIs may be more appropriate. Disease-specific outcomes may be more useful than symptom reporting.

Cough and cough hypersensitivity as treatable traits of asthma

Cough is a common and troublesome symptom in people with asthma and is often associated with poorer asthma control and exacerbations. Apart from asthma, other causes or comorbidities might underlie cough in asthma, such as rhinosinusitis and bronchiectasis. Eosinophilic inflammation and bronchoconstriction can lead to an acute episode of cough or worsen chronic cough. Cough hypersensitivity with laryngeal paraesthesia, allotussia, and hypertussia might underlie the cough of asthma through augmented sensory nerve excitability of upper-airway vagal sensory nerves. Cough associated with bronchoconstriction and type 2 inflammation should respond to inhaled corticosteroids and long-acting β-adrenoceptor agonist therapy. For cough hypersensitivity in adults, speech and language therapy and neuromodulators (eg, gabapentin) could be considered. In children, there is no consistent association of asthma with cough sensitivity or between cough and asthma severity. Further research is needed to realise the potential of cough as a measure of asthma control, to understand the mechanisms of cough in asthma, and to develop safe, effective treatments and a precision-medicine approach to the management of cough in asthma in children and adults.

Effectiveness of budesonide formoterol fixed-dose combination MDI in reducing cough symptoms in COVID-19 patients: A real-world evidence study

Background

Cough is a wearisome and exasperating symptom affecting the daily life of the infected patient. Cough due to coronavirus disease 2019 (COVID-19) causes excessive morbidity in human populations globally. Apart from the morbidity associated with cough, it also enhances the transmission of this viral infection through droplets. Therefore, curbing cough is crucial to limit its spread. Patients often administer over-the-counter products and antitussive agents, which have no proven benefit. The present study was undertaken to find out if cough associated with COVID-19 and other indicative clinical outcomes is alleviated with a budesonide/formoterol fixed-dose combination (FDC) metered-dose inhaler (MDI).

Materials and Methods

A prospective observational study was conducted in mild COVID-19 patients who presented with a cough score ≥8 at presentation. Patients who were initiated on ICS-LABA MDI were observed as group A and those who were not initiated on MDI were observed as Group B. Cough symptom score (at baseline and on day 3 and day 7), the incidence of hospital admission and/or death, and need for mechanical ventilation were documented. Prescribing patterns of anti-cough medications were also noted and analysed.

Results

Compared to group B, a higher mean cough score reduction was noted for group A patients at day 3 and day 7 when compared to the baseline, and this was significant at P < 0.001. A significant negative correlation was also observed between mean latency of MDI initiation from the symptom onset and mean cough score reduction. Analysis of the proportion of patients prescribed medications to treat cough showed that overall, 10.78% did not require these, with a greater proportion in group A compared to group B.

Conclusion

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) COVID-19 who were treated with ICS-LABA MDI along with usual care benefitted significantly in terms of symptom reduction compared to usual care.

Risk factors contributing to impaired cough-specific quality of life at the time of admission for coronavirus disease 2019 treatment

Background

Cough is the most common symptom of coronavirus disease 2019 (COVID-19). However, the factors contributing to impaired cough-specific quality of life (QoL) during the acute phase of COVID-19 infection remain unknown. We sought to identify such factors using the Japanese version of acute cough with the Leicester Cough Questionnaire (LCQ-acute).

Methods

Three hundred and two patients with COVID-19 admitted to Aichi Hospital between October 2020 and October 2021 completed the LCQ-acute at the time of admission. Clinical indices at the time of admission, such as presenting symptoms including cough, patient characteristics, disease severity, and biomarkers, were reviewed from the medical records. The impact of cough-specific QoL on clinical indices was assessed using two- or three-group comparisons and Pearson's correlation coefficient. Multivariate analysis was performed to determine the factors contributing to impaired cough-specific QoL at the time of admission for COVID-19 treatment.

Results

Two hundred and nine patients (69.2%) were coughing at the time of admission. Cough prevalence was highest, but cough-specific QoL was lowest at 8-11 days after onset. Multivariate analysis revealed that female sex, young age, gastrointestinal (GI) symptoms, and dysgeusia and/or dysosmia contributed to impaired cough-specific QoL at the time of admission for COVID-19 treatment, along with systemic and respiratory symptoms such as fever, higher C-reactive protein (CRP) levels, sputum, and dyspnea.

Conclusions

Female sex, young age, asthma, GI symptoms, dysgeusia, and/or dysosmia, along with systemic and respiratory symptoms, indicated impaired cough-specific QoL at the time of admission for COVID-19 treatment.

Effects of <em>Pelargonium sidoides</em> extract EPs 7630 on acute cough and quality of life – a meta-analysis of randomized, placebo-controlled trials

Background

Cough is a leading symptom of viral acute respiratory infections such as acute bronchitis (AB) and the common cold (CC), which can be debilitating and may persist for several weeks. We investigated whether treatment with Pelargonium extract EPs 7630 may reduce cough and improve disease-related quality of life (QoL).

Methods

We performed a meta-analysis of randomized, placebo-controlled trials investigating the efficacy of EPs 7630 in AB or CC. Efficacy analyses included change from baseline in a cough intensity score, remission of cough, and disease-associated impairments of QoL.

Results

Data of 2,195 participants from 11 trials (3 in children/adolescents with AB, 3 in adults with AB, 5 in adults with CC) were eligible. In children/adolescents with AB, 79.6% of participants treated with EPs 7630 and 41% treated with placebo showed a reduction in the intensity of cough by at least 50% of baseline values at day 7 [meta-analysis rate/risk ratio (RR), EPs 7630 / placebo: 1.86 (95% CI: 1.34; 2.95)], and 18.0% vs 5.5% presented with complete remission of cough [RR: 2.91 (95% CI: 1.26; 6.72)]. In adults with AB, 88.7% of participants in the EPs 7630 group and 47.6% in the placebo group showed a ≥50% response for cough intensity [RR: 2.13 (95% CI: 1.37; 3.31)], while 26.0% vs 6.3% did not cough any more at day 7 [RR: 5.00 [95% CI: 3.10; 8.07)]. Cough scale results were supported by significant improvements over placebo in the pursuit of normal daily activities and other QoL measures. In CC, 56.8% of participants treated with EPs 7630 and 38.8% treated with placebo showed a ≥50% cough intensity reduction [RR: 1.40 (95% CI: 1.19; 1.65)] at day 5, while 26.1% versus 18.4% showed complete remission of cough for EPs 7630 and placebo, respectively [RR: 1.40 (95% CI: 1.06; 1.84)]. CCassociated pain/discomfort and impairment of usual activities were no longer present in 41.5% and 48.8% of participants treated with EPs 7630 compared to less than 40% of patients in the placebo group.

Conclusions

The results show that EPs 7630 reduces the burden and leads to earlier remission of cough. Advantages for EPs 7630 were also reflected in self-rated measures of disease-associated QoL. Of note, patients treated with the herbal product felt able to resume their usual daily activities sooner.

IAPV-Induced Paralytic Symptoms Associated with Tachypnea via Impaired Tracheal System Function

Although it had been reported that Israeli acute paralysis virus (IAPV) can cause systemic infection in honey bees, little is known about how it establishes this infection and results in the typical symptoms, paralysis and trembling. Here, we used our previously constructed IAPV infectious clone to investigate viral loads in different tissues of honey bees and further identify the relation between tissue tropism and paralytic symptoms. Our results showed that tracheae showed a greater concentration of viral abundance than other tissues. The abundance of viral protein in the tracheae was positively associated with viral titers, and was further confirmed by immunological and ultrastructural evidence. Furthermore, higher viral loads in tracheae induced remarkable down-regulation of succinate dehydrogenase and cytochrome c oxidase genes, and progressed to causing respiratory failure of honey bees, resulting in the appearance of typical symptoms, paralysis and body trembling. Our results showed that paralysis symptoms or trembling was actually to mitigate tachypnea induced by IAPV infection due to the impairment of honey bee tracheae, and revealed a direct causal link between paralysis symptoms and tissue tropism. These findings provide new insights into the understanding of the underlying mechanism of paralysis symptoms of honey bees after viral infection and have implications for viral disease prevention and specific therapeutics in practice.

Potentials of Antitussive Traditional Persian Functional Foods for COVID-19 Therapy†

Coronavirus disease 2019 is a worldwide pandemic resulting in a severe acute respiratory syndrome. Remdesivir is the only FDA-approved drug for hospitalized patients older than age 12. It shows the necessity of finding new therapeutic strategies. Functional foods (FFs) could have co-therapeutic and protective effects against COVID-19 infection. Traditional Persian medicine (TPM), one of the safest and most popular schools of medicine for hundreds of years, has recommended potential FF candidates to manage such a global pandemic. To reveal the potential of TPM in terms of antitussive FFs, traditional Persian pharmacopoeia "Qarabadin-e-Salehi" was searched using the keywords "Soaal" and "Sorfeh." Also, a search of MEDLINE, PubMed Central, Google Scholar, and Science Direct was performed for the relevant literature published from the inception up to March 2021. A combination of search terms including "cough, antitussive, antioxidant, anti-inflammation, antiviral, COVID-19, mucoactive, mucolytic, expectorant, and mucoregulatory" was also applied. The potential mechanism of action in SARS-CoV-2 infection was discussed. Twelve TPM FFs were found including Laooqs, Morabbas, a Saviq, a soup, and a syrup. They are combinations of two to seven ingredients. Natural compounds of mentioned formulations have the main pharmacological mechanisms including antiviral, anti-inflammatory, antioxidant, antihistamine, bronchodilator, immunomodulatory, and mucoactive effects as well as central or peripheral antitussive activities. FFs are cost-effective, easily accessible, and safe options for both treatment and prevention of COVID-19. They might have positive psychological effects along with their pharmacological effects and nutritional virtues. They could also manage persistent respiratory discomforts after recovery from COVID-19.

Mycobacterium tuberculosis Sulfolipid-1 Activates Nociceptive Neurons and Induces Cough

Pulmonary tuberculosis, a disease caused by Mycobacterium tuberculosis (Mtb), manifests with a persistent cough as both a primary symptom and mechanism of transmission. The cough reflex can be triggered by nociceptive neurons innervating the lungs, and some bacteria produce neuron-targeting molecules. However, how pulmonary Mtb infection causes cough remains undefined, and whether Mtb produces a neuron-activating, cough-inducing molecule is unknown. Here, we show that an Mtb organic extract activates nociceptive neurons in vitro and identify the Mtb glycolipid sulfolipid-1 (SL-1) as the nociceptive molecule. Mtb organic extracts from mutants lacking SL-1 synthesis cannot activate neurons in vitro or induce cough in a guinea pig model. Finally, Mtb-infected guinea pigs cough in a manner dependent on SL-1 synthesis. Thus, we demonstrate a heretofore unknown molecular mechanism for cough induction by a virulent human pathogen via its production of a complex lipid.

Roles of citric acid in conjunction with saline nebulization in experimental tracheostomy in guinea pigs

PURPOSE

Tracheostomy usually accompanied by the impairment of cough reflex, which may affect the clearance of secretions and result in the occurrence and development of pulmonary inflammation. Previous research has demonstrated that citric acid could effectively evoke cough. However, there are limited data available on this topic specific to the cough stimulation method, and the roles of citric acid in tracheostomy still remain obscure. The aims of present study were to identify the potential roles of citric acid in conjunction with saline nebulization in tracheostomy in guinea pigs.

MATERIALS AND METHODS

Experimental tracheostomy model was induced in guinea pigs, and different nebulization interventions were implemented. The expression of P-selectin and platelet count were analyzed by flow cytometer and automatic globulimeter, the histological changes in trachea and lung tissue were assessed by hematoxylin and eosin staining, and the inflammatory cytokines and substance P (SP) levels in bronchoalveolar lavage fluid were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Tracheostomy resulted in the disorder of trachea mucosa and cilia, the inflammatory cell infiltration in lung tissue, the increase of IL-6, TNF-α levels and the decrease of SP level. Citric acid alone increase the SP level, and the joint action of citric acid and saline nebulization further showed significantly beneficial effects on pathological, inflammatory changes and SP level.

CONCLUSIONS

Citric acid combined with saline nebulization contributes to the alleviation of tracheotomy-induced tracheal damage and pulmonary inflammation in an experimental tracheostomy model in guinea pigs. This may provide novel insights into the inflammation management and cough recovery after tracheostomy.

The human viral challenge model: accelerating the evaluation of respiratory antivirals, vaccines and novel diagnostics

The Human Viral Challenge (HVC) model has, for many decades, helped in the understanding of respiratory viruses and their role in disease pathogenesis. In a controlled setting using small numbers of volunteers removed from community exposure to other infections, this experimental model enables proof of concept work to be undertaken on novel therapeutics, including vaccines, immunomodulators and antivirals, as well as new diagnostics.Crucially, unlike conventional phase 1 studies, challenge studies include evaluable efficacy endpoints that then guide decisions on how to optimise subsequent field studies, as recommended by the FDA and thus licensing studies that follow. Such a strategy optimises the benefit of the studies and identifies possible threats early on, minimising the risk to subsequent volunteers but also maximising the benefit of scarce resources available to the research group investing in the research. Inspired by the principles of the 3Rs (Replacement, Reduction and Refinement) now commonly applied in the preclinical phase, HVC studies allow refinement and reduction of the subsequent development phase, accelerating progress towards further statistically powered phase 2b studies. The breadth of data generated from challenge studies allows for exploration of a wide range of variables and endpoints that can then be taken through to pivotal phase 3 studies.We describe the disease burden for acute respiratory viral infections for which current conventional development strategies have failed to produce therapeutics that meet clinical need. The Authors describe the HVC model's utility in increasing scientific understanding and in progressing promising therapeutics through development.The contribution of the model to the elucidation of the virus-host interaction, both regarding viral pathogenicity and the body's immunological response is discussed, along with its utility to assist in the development of novel diagnostics.Future applications of the model are also explored.

Effects of indole alkaloids from leaf of Alstonia scholaris on post-infectious cough in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Leaf of Alstonia scholaris (L.) R. Br. (Apocynaceae), a wide used ethic-medicine in many Asia and Africa counties, has also been recorded as the common traditional Chinese medicine for treatment of illnesses in respiratory system by Dai people.

AIM OF THE STUDY

To provide experimental data of clinical adaption of total indole alkaloids (TA) from leaf of A. scholaris for treating post-infectious cough in phase II clinical trial.

MATERIALS AND METHODS

To model post-infectious cough, all animals except control group were instilled intra-tracheal with lipopolysaccharide (LPS) (80 μg/50 µL/mouse), followed by subsequent exposure to cigarette smoke (CS) for 30 min per day for a total of 30 days. Mice were orally given TA at dose of 10, 25, 50 mg/kg, and four main alkaloids (Sch: scholaricine, Epi: 19-epischolaricine, Val: vallesamine, Pic: picrinine) once daily. Cellular infiltration was assessed in the broncho-alveolar lavage fluid (BALF). Expression of interleukin-6 (IL-6) and C-reactive protein (CRP) in the serum was determined, the superoxide dismutase (SOD) activity as well as malondialdehyde (MDA) content in the serum and homogenate were examined. Finally, histopathological examination in the lungs was assessed by H. E. staining.

RESULTS

After administration of TA and four major alkaloids respectively, the symptoms of cough in mice were obviously attenuated. Total white blood cells (WBC) and neutrophils (NEU) amounts in BALF were reduced obviously and the pathological damage of lung was also attenuated. There was also significant reduction in IL-6, CRP, MDA and a marked improvement in SOD.

CONCLUSIONS

The efficacy of indole alkaloids against post-infectious cough (PIC) was shown in the down-regulation of inflammatory cells, cytokines, and the balance of antioxidants. What's more, the pharmacological effects of TA were better than single indole alkaloid, which might be related to the synergic effect of four major alkaloids.

Respiratory virus infection up-regulates TRPV1, TRPA1 and ASICS3 receptors on airway cells

Receptors implicated in cough hypersensitivity are transient receptor potential vanilloid 1 (TRPV1), transient receptor potential cation channel, Subfamily A, Member 1 (TRPA1) and acid sensing ion channel receptor 3 (ASIC3). Respiratory viruses, such as respiratory syncytial virus (RSV) and measles virus (MV) may interact directly and/or indirectly with these receptors on sensory nerves and epithelial cells in the airways. We used in vitro models of sensory neurones (SHSY5Y or differentiated IMR-32 cells) and human bronchial epithelium (BEAS-2B cells) as well as primary human bronchial epithelial cells (PBEC) to study the effect of MV and RSV infection on receptor expression. Receptor mRNA and protein levels were examined by qPCR and flow cytometry, respectively, following infection or treatment with UV inactivated virus, virus-induced soluble factors or pelleted virus. Concentrations of a range of cytokines in resultant BEAS-2B and PBEC supernatants were determined by ELISA. Up-regulation of TRPV1, TRPA1 and ASICS3 expression occurred by 12 hours post-infection in each cell type. This was independent of replicating virus, within the same cell, as virus-induced soluble factors alone were sufficient to increase channel expression. IL-8 and IL-6 increased in infected cell supernatants. Antibodies against these factors inhibited TRP receptor up-regulation. Capsazepine treatment inhibited virus induced up-regulation of TRPV1 indicating that these receptors are targets for treating virus-induced cough.

Efficacy and tolerability of a polysaccharide-resin-honey based cough syrup as compared to carbocysteine syrup for children with colds: a randomized, single-blinded, multicenter study

BACKGROUND

Available pediatric treatments for acute cough are limited by lack of demonstrated efficacy. The objective of this trial is to compare the effects of a polysaccharide-resin-honey based cough syrup, and carbocysteine syrups on nocturnal and daytime cough associated with childhood upper respiratory tract infections (URIs).

METHODS

Using a single-blind randomization design, the study recruited children from 4 general pediatric community clinics. Participants included 150 children aged 2 to 5 years with an URI, nocturnal and daytime cough and illness duration of ≤7 days. To be eligible, children had to be free of medication on the day before presentation. A survey was administered to parents on 4 consecutive days beginning from the day of presentation in clinic. Children received the study preparation on the first evening and then 3 times per day for 3 further days. Main outcome measures were cough frequency, cough severity, bothersome nature of cough, and quality of sleep for both child and parent.

RESULTS

Both preparations were well tolerated and cough improved over the study period. After one night and on all survey days, there was a significantly better result for polysaccharide-resin-honey (P<0.05) for all the main outcome measures. The trend of improvement over the 4 days was steeper for polysaccharide-resin-honey (P<0.05) with regards to all cough parameters.

CONCLUSIONS

Both polysaccharide-resin-honey and carbocysteine cough syrups were well tolerated in children over 2 years of age. The polysaccharide-resin-honey syrup was associated with a more rapid and greater improvement in all clinical cough symptoms measured, beginning from the first night of therapy. Both nocturnal and daytime cough improved, as did sleep quality for both children and parents.

Characterization of urge to cough and cough symptoms associated with the common cold: results of a US internet survey

OBJECTIVES

Our knowledge of cough physiology is limited despite years of study. Even less is known about the sensation of urge to cough. Given that limited clinical data are available about urge to cough and cough attributes during a common cold, we sought to gain insights into experiences and perceptions related to these symptoms.

METHODS

An internet survey consisting of 51 questions was fielded in the United States. Eligible survey participants included men and women aged 18 years and older who had suffered from a cold with cough within the three months preceding the survey. Participants who confirmed suffering from recurrent cough, asthma, chronic bronchitis, chronic obstructive pulmonary disease, cystic fibrosis, or gastrointestinal reflux were excluded.

RESULTS

Of 19,530 initial respondents, 8011 had a cold in the past three months. Of these, 6484 (81%) had experienced cough symptoms; 2708 respondents with cough due to cold and no exclusionary condition made up the analysis sample. Most respondents (62%) reported that cough developed one to two days after the onset of cold symptoms, and 45% felt that cough worsened their other cold symptoms. In 69% of respondents, cough outlasted other cold symptoms. Urge to cough was reported by 98% of respondents, and among these respondents, 64% described it as uncontrollable and 65% rated severity as moderate. More than half of respondents (57%) considered the sensation of urge to cough and the act of coughing as equally bothersome. Although urge to cough and inability to control cough were the most bothersome aspects of cough due to cold, few (<20%) respondents asked healthcare providers for treatment recommendations.

CONCLUSION

Symptoms of urge to cough and cough are common and have a significant impact on cold sufferers. Understanding attributes of these symptoms may provide insights for effective management and the development of novel treatment strategies.

Airway Vagal Neuroplasticity Associated with Respiratory Viral Infections

Respiratory virus infections leads to coughing, sneezing, and increases in reflex parasympathetic bronchoconstriction and secretions. These responses to viral infection are exclusively or largely secondary to changes in the function of the nervous system. For many with underlying airway pathologies such as asthma and COPD, this neuroplasticity can lead to disease exacerbations and hospitalization. Relatively little is understood about the cellular and molecular mechanisms that underlie the changes in neuronal control of the respiratory tract during viral infection, but the evidence supports the idea that changes occur in the physiology of both the sensory and autonomic innervation. Virus infection can lead to acute increases in the activity of sensory nerves as well as to genetic changes causing alterations in sensory nerve phenotype. In addition, respiratory viral infections are associated with changes in the control of neurotransmitter release from cholinergic nerve endings terminating at the level of the airway smooth muscle.

Effect of Lactobacillus paracasei subsp. paracasei, L. casei 431 on immune response to influenza vaccination and upper respiratory tract infections in healthy adult volunteers: a randomized, double-blind, placebo-controlled, parallel-group study

BACKGROUND

Probiotics can modulate the immune system in healthy individuals and may help reduce symptoms related to respiratory infections.

OBJECTIVE

The objective of the study was to investigate the effect of the probiotic strain Lactobacillus paracasei subsp. paracasei, L. casei 431 (Chr. Hansen A/S) (hereafter, L. casei 431) on immune response to influenza vaccination and respiratory symptoms in healthy adults.

DESIGN

A randomized double-blind, placebo-controlled trial was conducted in 1104 healthy subjects aged 18-60 y at 2 centers in Germany and Denmark. Subjects were randomly assigned to receive an acidified milk drink containing ≥10(9) colony-forming units of L. casei 431 (n = 553) or placebo (n = 551) for 42 d. After 21 d, subjects received the seasonal influenza vaccination. The primary outcome was seroprotection rate (anti-influenza antibody titers by hemagglutination inhibition) 21 d after vaccination. Other outcomes were seroconversion rate and mean titers, influenza A-specific antibodies and incidence, and duration and severity of upper respiratory symptoms. Antibiotic use and use of health care resources were recorded.

RESULTS

There was no effect of L. casei 431 on immune responses to influenza vaccination. Generalized linear mixed modeling showed a shorter duration of upper respiratory symptoms in the probiotic group than in the placebo group (mean ± SD: 6.4 ± 6.1 vs. 7.3 ± 9.7 d, P = 0.0059) in the last 3 wk of the intervention period. No statistically significant differences were found for incidence or severity.

CONCLUSIONS

Daily consumption of L. casei 431 resulted in no observable effect on the components of the immune response to influenza vaccination but reduced the duration of upper respiratory symptoms. The trial was registered at www.isrctn.com as ISRCTN08280229.

Targeting TRP channels for chronic cough: from bench to bedside

Cough is currently the most common reason for patients to visit a primary care physician in the UK, yet it remains an unmet medical need. Current therapies have limited efficacy or have potentially dangerous side effects. Under normal circumstances, cough is a protective reflex to clear the lungs of harmful particles; however, in disease, cough can become excessive, dramatically impacting patients' lives. In many cases, this condition is linked to inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD), but can also be refractory to treatment and idiopathic in nature. Therefore, there is an urgent need to develop therapies, and targeting the sensory afferent arm of the reflex which initiates the cough reflex may uncover novel therapeutic targets. The cough reflex is initiated following activation of ion channels present on vagal sensory afferents. These ion channels include the transient receptor potential (TRP) family of cation-selective ion channels which act as cellular sensors and respond to changes in the external environment. Many direct activators of TRP channels, including arachidonic acid derivatives, a lowered airway pH, changes in temperature, and altered airway osmolarity are present in the diseased airway where responses to challenge agents which activate airway sensory nerve activity are known to be enhanced. Furthermore, the expression of some TRP channels is increased in airway disease. Together, this makes them promising targets for the treatment of chronic cough. This review will cover the current understanding of the role of the TRP family of ion channels in the activation of airway sensory nerves and cough, focusing on four members, transient receptor potential vanilloid (TRPV) 1, transient receptor potential ankyrin (TRPA) 1, TRPV4, and transient receptor potential melastatin (TRPM) 8 as these represent the channels where most information has been gathered with relevance to the airways. We will describe recent data and highlight the possible therapeutic utility of specific TRP channel antagonists as antitussives in the clinic.

Effect of viral upper respiratory tract infection on cough reflex sensitivity

Acute viral upper respiratory tract infection (URI; common cold) is among the most common medical conditions affecting man, with cough being a typical feature of the associated syndrome. Studies employing capsaicin inhalation challenge to measure cough reflex sensitivity have demonstrated a transient tussive hyperresponsiveness induced by URI that reverts to normal by 4-8 weeks post infection. Mechanisms proposed to explain the induction of cough by URI include a number of infection-associated airway effects, such as enhanced release of cytokines, neurotransmitters, and leukotrienes; increased neural receptor levels; reduced activity of neutral endopeptidases; transient modulation of afferent neural activity; mucus hypersecretion; and, possibly, effects on cholinergic motor pathways. Recent studies evaluating urge-to-cough (UTC), the sensation of irritation preceding the motor act of coughing, have demonstrated that URI induces a transient enhancement of UTC analogous to the effect observed on cough reflex sensitivity. The recently introduced concept of the Cough Hypersensitivity Syndrome may provide an explanation for the commonly observed clinical phenomenon of acute viral URI triggering what will develop into chronic, refractory cough in a subgroup of patients.

Antitussive drugs--past, present, and future

Cough remains a serious unmet clinical problem, both as a symptom of a range of other conditions such as asthma, chronic obstructive pulmonary disease, gastroesophageal reflux, and as a problem in its own right in patients with chronic cough of unknown origin. This article reviews our current understanding of the pathogenesis of cough and the hypertussive state characterizing a number of diseases as well as reviewing the evidence for the different classes of antitussive drug currently in clinical use. For completeness, the review also discusses a number of major drug classes often clinically used to treat cough but that are not generally classified as antitussive drugs. We also reviewed a number of drug classes in various stages of development as antitussive drugs. Perhaps surprising for drugs used to treat such a common symptom, there is a paucity of well-controlled clinical studies documenting evidence for the use of many of the drug classes in use today, particularly those available over the counter. Nonetheless, there has been a considerable increase in our understanding of the cough reflex over the last decade that has led to a number of promising new targets for antitussive drugs being identified and thus giving some hope of new drugs being available in the not too distant future for the treatment of this often debilitating symptom.

Chronic cough in preschool children

Cough may be the first overt sign of disease of the airways or lungs when it represents more than a defense mechanism, and may by its persistence become a helpful pointer of potential disease for both patient and physician. On the other hand, impairment or absence of the coughing mechanism can be harmful and even fatal; this is why cough suppression is rarely indicated in childhood. Pediatricians are concerned more with the etiology of the cough and making the right diagnosis. Whereas chronic cough in adults has been universally defined as a cough that lasts more than 8 weeks, in childhood, different timing has been reported. Many reasons support defining a cough that lasts more than 4 weeks in preschool children as chronic, however; and this is particularly true when the cough is wet. During childhood, the respiratory tract and nervous system undergo a series of anatomical and physiological maturation processes that influence the cough reflex. In addition, immunological response undergoes developmental and memorial processes that make infection and congenital abnormalities the overwhelming causes of cough in preschool children. Cough in children should be treated on the basis of etiology, and there is no evidence in support of the use of medication for symptomatic cough relief or adopting empirical approaches. Most cases of chronic cough in preschool age are caused by protracted bacterial bronchitis, tracheobronchomalacia, foreign body aspiration, post-infectious cough or some combination of these. Other causes of chronic cough, such as bronchiectasis, asthma, gastroesophageal reflux, and upper respiratory syndrome appear to be less frequent in this age group. The prevalence of each depends on the population in consideration, the epidemiology of infectious diseases, socioeconomic aspects, and the local health system.

PCR based bronchoscopic detection of common respiratory pathogens in chronic cough: a case control study

BACKGROUND

Viral respiratory tract infection is the most frequent cause of acute cough and is reported at onset in about one third of patients with chronic cough. Persistent infection is therefore one possible explanation for the cough reflex hypersensitivity and pulmonary inflammation reported in chronic cough patients.

METHODS

Bronchoscopic endobronchial biopsies and bronchoalveolar lavage cell counts were obtained from ten healthy volunteers and twenty treatment resistant chronic cough patients (10 selected for lavage lymphocytosis). A screen for known respiratory pathogens was performed on biopsy tissue. Chronic cough patients also underwent cough reflex sensitivity testing using citric acid.

RESULTS

There was no significant difference in incidence of infection between healthy volunteers and chronic cough patients (p = 0.115) or non-lymphocytic and lymphocytic groups (p = 0.404). BAL cell percentages were not significantly different between healthy volunteers and chronic cough patients without lymphocytosis. Lymphocytic patients however had a significantly raised percentage of lymphocytes (p < 0.01), neutrophils (p < 0.05), eosinophils (p < 0.05) and decreased macrophages (p < 0.001) verses healthy volunteers. There was no significant difference in the cough reflex sensitivity between non-lymphocytic and lymphocytic patients (p = 0.536).

CONCLUSIONS

This study indicates latent infection in the lung is unlikely to play an important role in chronic cough, but a role for undetected or undetectable pathogens in either the lung or a distal site could not be ruled out.

TRIALS REGISTRATION

Current Controlled Trials ISRCTN62337037 & ISRCTN40147207.

The influence of virus infections on the course of COPD

Chronic obstructive pulmonary disease (COPD) is extensively influenced by viral infections. The mechanisms of how viral agents affect the pathogenesis and prognosis of COPD are numerous. In general, patients with infectious exacerbations are characterized by longer hospitalization periods and greater impairment of several lung function parameters than those with non-infectious exacerbations. Prodromal, clinical, and outcome parameters fail to distinguish virally from non-virally induced illnesses in cases of exacerbations. The importance of infections with respiratory and non-respiratory viral agents for pathogenesis and course of COPD is detailed. Human adenovirus, non-respiratory viruses including human immunodeficiency virus, human metapneumovirus, influenza virus, human rhinovirus, and respiratory syncytial virus are especially stressed.

Characteristics of Chinese patients with cough in primary care centre

Background

Cough is one of the most common respiratory symptoms and is well characterized in specialized cough clinics with high success rates of diagnosis and treatment. However, there is a paucity of data regarding cough in primary care settings. The present study aimed at investigating clinical epidemiology of cough through a national study of two questionnaire surveys sent to primary care physicians in China.

Methods

Approximately 18,000 subjects recruited were having daytime or night symptoms of cough and diagnoses of respiratory disease from February 2005 to April 2006 as Survey 1 and from June 2007 to December 2007 as Survey 2. Patients suffering from respiratory malignancy, hyperthyroidism, hypertension, heart disease, diabetes, severe hypohepatia or renal dysfunction, pregnancy, possible pregnancy or lactation, neutropenia were not eligible. Information regarding demography, history of allergies, symptomatic profile, treatment and curative effects for cough was elicited.

Results

8216 questionnaires were collected in Survey 1 and 9711 in Survey 2. The mean values of ages were 25.7 and 22.3 years old, respectively. Symptoms included expectoration (74% and 76%), wheeze (59% and 74%), breathlessness (22% and 26%), chest pain (9% and 13%) and fever (15% and 18%). About 15% and 23% patients had hypersusceptibility, of whom 6% to 17% had a family history. More than 50% of the cases had histories of allergic rhinitis, asthma, conjunctivitis or atopic dermatitis. Asthma, COPD, and bronchitis were dominant etiologies of cough. Procaterol or the combination of antibiotics and steroids were used as the treatment.

Conclusion

Causes and outcomes of cough differed with ages and time in this particular national study, while successful and precise diagnosis and management of cough in primary care settings need to be further improved in China.

Limited effects of Muc1 deficiency on mouse adenovirus type 1 respiratory infection

Muc1 (MUC1 in humans) is a membrane-tethered mucin that exerts anti-inflammatory effects in the lung during bacterial infection. Muc1 and other mucins are also likely to form a protective barrier in the lung. We used mouse adenovirus type 1 (MAV-1, also known as MAdV-1) to determine the role of Muc1 in the pathogenesis of an adenovirus in its natural host. Following intranasal inoculation of wild type mice, we detected increased TNF-α, a cytokine linked to Muc1 production, but no consistent changes in the production of lung Muc1, Muc5ac or overall lung mucus production. Viral loads were modestly higher in the lungs of Muc1(-/-) mice compared to Muc1(+/+) mice at several early time points but decreased to similar levels by 14 days post infection in both groups. However, cellular inflammation and the expression of CXCL1, CCL5, and CCL2 did not significantly differ between Muc1(-/-) and Muc1(+/+) mice. Our data therefore suggest that Muc1 may contribute to a physical barrier that protects against MAV-1 respiratory infection. However, our data do not reveal an anti-inflammatory effect of Muc1 that contributes to MAV-1 pathogenesis.

Cough reflex sensitivity is increased in guinea pigs with parainfluenza virus infection

The purpose of this study was to investigate for the change in cough reflex sensitivity (CRS) caused by parainfluenza virus type 3 (PIV3) infection. Guinea pigs were randomized into a vehicle control, an asthma control, or 1 of 4 PIV3-inoculated groups (referred to as postinfection day [PID] 6, 12, 28, and 42 groups). Evidence of viral protein and nucleic acid within the lung confirmed successful PIV3 infection. Plethysmography was used to assess CRS and airway reaction and airway inflammation was assessed via bronchoalveolar lavage fluid cytology and lung histopathology. Compared with the vehicle control group, CRS was significantly increased in all PID groups (P <.05) in concert with an obvious airway hyperresponsiveness in the PID 6 group. Though a small increase in CRS in the asthma control group was noted, it was not significant compared to the vehicle control group. Total cell counts from the bronchoalveolar lavage fluid of all PIV3-inoculated groups increased markedly and the number of lymphocytes was significantly increased in the PID 6 and PID 12 groups. The lung pathology of PIV3-inoculated animals showed airway inflammation without pneumonia in the acute infectious phase. The temporal and spatial variation of CRS may be the essential mechanism of cough caused by PIV3.

Efficacy and safety of an antiviral Iota-Carrageenan nasal spray: a randomized, double-blind, placebo-controlled exploratory study in volunteers with early symptoms of the common cold

BACKGROUND

The common cold, the most prevalent contagious viral disease in humans still lacks a safe and effective antiviral treatment. Iota-Carrageenan is broadly active against respiratory viruses in-vitro and has an excellent safety profile. This study investigated the efficacy and safety of an Iota-Carrageenan nasal spray in patients with common cold symptoms.

METHODS

In a randomized, double-blind, placebo-controlled exploratory trial, 35 human subjects suffering from early symptoms of common cold received Iota-Carrageenan (0.12%) in a saline solution three times daily for 4 days, compared to placebo.

RESULTS

Administration of Iota-Carrageenan nasal spray reduced the symptoms of common cold (p = 0.046) and the viral load in nasal lavages (p = 0.009) in patients with early symptoms of common cold. Pro-inflammatory mediators FGF-2, Fractalkine, GRO, G-CSF, IL-8, IL-1alpha, IP-10, IL-10, and IFN-alpha2 were reduced in the Iota-Carrageenan group.

CONCLUSIONS

Iota-Carrageenan nasal spray appears to be a promising treatment for safe and effective treatment of early symptoms of common cold. Larger trials are indicated to confirm the results.

Interrupting the cough reflex in asthma

PURPOSE OF REVIEW

Although cough is one of the defining symptoms of asthma, wheeze, chest tightness and breathlessness have generally received more attention. The impact of coughing for patients may be more important than currently appreciated and has been rated more troublesome than wheeze, chest tightness or disturbance of sleep.

RECENT FINDINGS

Studies objectively measuring cough in asthma reveal that cough frequencies vary from those similar to healthy volunteers to cough counts comparable to patients presenting with chronic cough, but the potential triggers for cough in asthma are poorly understood. This review discusses our current knowledge of cough in asthma, potential mechanisms that may provoke coughing, the effect of current treatments and possible future therapeutics.

SUMMARY

Cough in some asthma patients is a significant problem, deserving further attention in both clinical practice and clinical research.

Future directions in treating cough

Cough is a common and troublesome symptom that can be difficult to treat. New therapeutic options that are safe and more effective than those currently available are needed. In this article, the authors offer opinion on future directions in the treatment of cough, with a particular emphasis on the clinical syndrome associated with cough reflex hypersensitivity. In addition, the article provides an overview of some of the diagnostic technologies and promising drug targets likely to emerge from current clinical and scientific endeavor.

COPD and the response of the lung to tobacco smoke exposure

Chronic Obstructive Pulmonary Disease (COPD) is a major cause of death in the western world and increasing in prevalence in developing countries. COPD is characterised by irreversible airflow obstruction, loss of lung tissue, reduced quality of life and high rates of mortality. The major cause of COPD is tobacco smoke. The changes in the innate immune system directed by tobacco smoke exposure lead to a pronounced and chronic inflammation in the lung. This in turn leads to other pathological changes including remodelling and destruction of lung tissue. Tobacco smoke exposure also leads to infection of the lung by bacteria and viruses. These, bacteria, viruses and co-infection are key triggers of acute worsening's of COPD termed exacerbations. COPD exacerbations are an additional major factor in the morbidity and mortality within COPD and are also the major healthcare costs associated with the disease. Within this review we discuss the response of the immune system to cigarette smoke exposure and inappropriate harmful responses. Successful treatment strategies will need to balance the positive effects of reducing inflammatory aspects of the disease whilst retaining some of the needed immune responses triggered by tobacco smoke exposure.