Stephen Bianchi

Subversion of a Lysosomal Pathway Regulating Neutrophil Apoptosis by a Major Bacterial Toxin, Pyocyanin

Neutrophils undergo rapid constitutive apoptosis that is accelerated following bacterial ingestion as part of effective immunity, but is also accelerated by bacterial exotoxins as a mechanism of immune evasion. The paradigm of pathogen-driven neutrophil apoptosis is exemplified by the Pseudomonas aeruginosa toxic metabolite, pyocyanin. We previously showed pyocyanin dramatically accelerates neutrophil apoptosis both in vitro and in vivo, impairs host defenses, and favors bacterial persistence. In this study, we investigated the mechanisms of pyocyanin-induced neutrophil apoptosis. Pyocyanin induced early lysosomal dysfunction, shown by altered lysosomal pH, within 15 min of exposure. Lysosomal disruption was followed by mitochondrial membrane permeabilization, caspase activation, and destabilization of Mcl-1. Pharmacological inhibitors of a lysosomal protease, cathepsin D (CTSD), abrogated pyocyanin-induced apoptosis, and translocation of CTSD to the cytosol followed pyocyanin treatment and lysosomal disruption. A stable analog of cAMP (dibutyryl cAMP) impeded the translocation of CTSD and prevented the destabilization of Mcl-1 by pyocyanin. Thus, pyocyanin activated a coordinated series of events dependent upon lysosomal dysfunction and protease release, the first description of a bacterial toxin using a lysosomal cell death pathway. This may be a pathological pathway of cell death to which neutrophils are particularly susceptible, and could be therapeutically targeted to limit neutrophil death and preserve host responses.

Granulocyte apoptosis in the pathogenesis and resolution of lung disease

Apoptosis, programmed cell death, of neutrophil and eosinophil granulocytes is a potential control point in the physiological resolution of innate immune responses. There is also increasing evidence that cellular processes of apoptosis can be dysregulated by pathogens as a mechanism of immune evasion and that delayed apoptosis, resulting in prolonged inflammatory cell survival, is important in persistence of tissue inflammation. The identification of cell-type specific pathways to apoptosis may allow the design of novel anti-inflammatory therapies or agents to augment the innate immune responses to infection. This review will explore the physiological roles of granulocyte apoptosis and their importance in infectious and non-infectious lung disease.

DiPALS: Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis - a randomised controlled trial.

BACKGROUND Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease resulting in death, usually from respiratory failure, within 2-3 years of symptom onset. Non-invasive ventilation (NIV) is a treatment that when given to patients in respiratory failure leads to improved survival and quality of life. Diaphragm pacing (DP), using the NeuRx/4(®) diaphragm pacing system (DPS)™ (Synapse Biomedical, Oberlin, OH, USA), is a new technique that may offer additional or alternative benefits to patients with ALS who are in respiratory failure. OBJECTIVE The Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis (DiPALS) trial evaluated the effect of DP on survival over the study duration in patients with ALS with respiratory failure. DESIGN The DiPALS trial was a multicentre, parallel-group, open-label, randomised controlled trial incorporating health economic analyses and a qualitative longitudinal substudy. PARTICIPANTS Eligible participants had a diagnosis of ALS (ALS laboratory-supported probable, clinically probable or clinically definite according to the World Federation of Neurology revised El Escorial criteria), had been stabilised on riluzole for 30 days, were aged ≥ 18 years and were in respiratory failure. We planned to recruit 108 patients from seven UK-based specialist ALS or respiratory centres. Allocation was performed using 1 : 1 non-deterministic minimisation. INTERVENTIONS Participants were randomised to either standard care (NIV alone) or standard care (NIV) plus DP using the NeuRX/4 DPS. MAIN OUTCOME MEASURES The primary outcome was overall survival, defined as the time from randomisation to death from any cause. Secondary outcomes were patient quality of life [assessed by European Quality of Life-5 Dimensions, three levels (EQ-5D-3L), Short Form questionnaire-36 items and Sleep Apnoea Quality of Life Index questionnaire]; carer quality of life (EQ-5D-3L and Caregiver Burden Inventory); cost-utility analysis and health-care resource use; tolerability and adverse events. Acceptability and attitudes to DP were assessed in a qualitative substudy. RESULTS In total, 74 participants were randomised into the trial and analysed, 37 participants to NIV plus pacing and 37 to standard care, before the Data Monitoring and Ethics Committee advised initial suspension of recruitment (December 2013) and subsequent discontinuation of pacing (on safety grounds) in all patients (June 2014). Follow-up assessments continued until the planned end of the study in December 2014. The median survival (interquartile range) was 22.5 months (lower quartile 11.8 months; upper quartile not reached) in the NIV arm and 11.0 months (6.7 to 17.0 months) in the NIV plus pacing arm, with an adjusted hazard ratio of 2.27 (95% confidence interval 1.22 to 4.25; p = 0.01). CONCLUSIONS Diaphragmatic pacing should not be used as a routine treatment for patients with ALS in respiratory failure. FUTURE WORK It may be that certain population subgroups benefit from DP. We are unable to explain the mechanism behind the excess mortality in the pacing arm, something the small trial size cannot help address. Future research should investigate the mechanism by which harm or benefit occurs further. TRIAL REGISTRATION Current Controlled Trials ISRCTN53817913. FUNDING This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 45. See the HTA programme website for further project information. Additional funding was provided by the Motor Neurone Disease Association of England, Wales and Northern Ireland.

The use of non-invasive ventilation at end of life in patients with motor neurone disease: A qualitative exploration of family carer and health professional experiences

Background: Non-invasive ventilation improves quality and quantity of life in patients with motor neurone disease who have respiratory failure. Use of non-invasive ventilation may, however, result in complex clinical issues for end-of-life care, with concerns as to whether and how it should be withdrawn. Aim: This study aimed to describe carer and health professional experiences of end-of-life care of motor neurone disease patients using non-invasive ventilation. Design/participants: This article reports data from qualitative interviews with family carers and professionals following the death of patients with motor neurone disease who were using non-invasive ventilation in the final phase of the disease. Results: Ten of the 20 patients initiated on non-invasive ventilation were using it in the end-of-life phase of their disease, with 5 using it for 24 h/day. Interviews were carried out with nine family carers and 15 professionals. Nine recurring themes were identified in the data. Both carers and health-care professionals perceived that the terminal phase of motor neurone disease was unexpectedly rapid and that this often led to unplanned interactions with the emergency services. Carers of patients who used non-invasive ventilation perceived non-invasive ventilation as aiding patient comfort and anxiety at the end of life. Conclusions: The use of non-invasive ventilation was described as beneficial and was not perceived by carers or most professionals to have adversely impacted patient’s end-of-life experience. This study highlights variation in patient wishes regarding usage towards the end of life, uncertainty regarding appropriate management among professionals and the importance of disseminating end-of-life wishes.

The initiation of non-invasive ventilation for patients with motor neuron disease: Patient and carer perceptions of obstacles and outcomes

Abstract This study aimed to examine the experiences of patients with motor neuron disease and their carers following the recommendation to use non-invasive ventilation (NIV). Qualitative interviews were carried out with 20 patients and 17 carers within one month of NIV being initiated. The study identified a range of potential barriers to usage including: adverse impressions of the technology; sleep disturbance; the sensation of pressure and pulsing; dry mouth; and mask design issues. Patients/carers perceived benefits related to: increased energy; improved sleeping; enhanced carer well-being; improved breathing and increased speech clarity. A key factor described by patients and carers was the need to persevere to overcome the challenges associated with early NIV use. The study highlights the importance of patient perceptions of gains as a factor in their NIV usage decisions. While recognizing that older individuals with limb-onset disease were over-represented in the sample, key recommendations from the study are: availability of easily accessible in-person support for patients; for clinicians to pre-empt potential obstacles by discussing options such as humidification or alternative mask interfaces; the importance of discussing potential benefits in detail with patients; and optimization of secretion management prior to NIV trial.

A preliminary randomized trial of the mechanical insufflator-exsufflator versus breath-stacking technique in patients with amyotrophic lateral sclerosis

A major problem faced by patients with amyotrophic lateral sclerosis (ALS) in respiratory failure is the inability to cough effectively. Forty eligible ALS patients were randomized to the breath-stacking technique using a lung volume recruitment bag (n = 21) or mechanical insufflator-exsufflator MI-E (n = 19) and followed up at three-monthly intervals for at least 12 months or until death. Results showed that there were 13 episodes of chest infection in the breath-stacking group and 19 episodes in the MI-E group (p = 0.92), requiring 90 and 95 days of antibiotics, respectively (p = 0.34). The mean duration of symptoms per chest infection was 6.9 days in the breath-stacking group and 3.9 days in MI-E group (p = 0.16). There were six episodes of hospitalization in each group (p = 0.64). The chance of hospitalization, in the event of a chest infection, was 0.46 in the breath-stacking group and 0.31 in MI-E group (p = 0.47). Median survival in the breath-stacking group was 535 days and 266 days in the MI-E group (p = 0.34). The QoL was maintained above 75% of baseline for a median of 329 days in the breath-stacking group and 205 days in the MI-E group (p = 0.41). In conclusion, lack of statistically significant differences due to sub-optimal power and confounders precludes a definitive conclusion with respect to the relative efficacy of one cough augmentation technique over the other. This study however, provides useful lessons and informative data, needed to strengthen the power calculation, inclusion criteria and randomization factors for a large scale definitive trial. Until such a definitive trial can be undertaken, we recommend the breath-stacking technique as a low-cost, first-line intervention for volume recruitment and cough augmentation in patients with ALS who meet the criteria for intervention with non-invasive ventilation.

Using transcutaneous carbon dioxide monitor (TOSCA 500) to detect respiratory failure in patients with amyotrophic lateral sclerosis: A validation study

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition, respiratory failure being the commonest cause of death. Quality of life and survival can be improved by supporting respiratory function with non-invasive ventilation. Transcutaneous carbon dioxide monitoring is a non-invasive method of measuring arterial carbon dioxide levels enabling simple and efficient screening for respiratory failure. The aim of this study was to validate the accuracy of carbon dioxide level recorded transcutaneously with a TOSCA 500 monitor. It is a prospective, observational study of 40 consecutive patients with ALS, recruited from a specialist ALS clinic. The partial pressure of carbon dioxide (PCO2) in each patient was determined by both transcutaneous monitoring and by an arterialized ear lobe capillary blood sample. The carbon dioxide (CO2) levels obtained with these two methods were compared by Bland-Altman analysis. The results showed that the mean difference between arterialized and transcutaneous readings was − 0.083 kPa (SD 0.318). The Bland-Altman limits of agreement ranged from 0.553 to − 0.719 kPa. The difference was < 0.5 kPa in 90% of the recordings. Four of the 40 measurements had a difference of > 0.5 kPa, with a maximum recorded difference of 0.95 kPa. In conclusion, non-invasive carbon dioxide monitoring using a TOSCA monitor is a useful clinical tool in neurology practice. Users should be aware of the possibility of occasional inaccurate readings. A clinically unexpected or incompatible reading should be verified with a blood gas analysis, especially when a decision to provide ventilatory support is required.

The Impact on the Family Carer of Motor Neurone Disease and Intervention with Noninvasive Ventilation

BACKGROUND The diagnosis of motor neurone disease (MND) has a profound effect on the functioning and well-being of both the patient and their family, with studies describing an increase in carer burden and depression as the disease progresses. AIM This study aimed to assess whether patient use of noninvasive ventilation (NIV) impacted on their family carer, and to explore other sources of carer burden. DESIGN The study used qualitative interviews and scaled measures of carer health and well-being completed at three monthly intervals until patient end of life. PARTICIPANTS Sixteen family carers were followed up over a period ranging from one month to two years. RESULTS NIV was perceived as having little impact on carer burden. The data however highlighted a range of sources of other burdens relating to the physical strain of caring. The Medical Outcomes Study Short Form (SF-36 Health Survey) Physical Component Summary (PCS) scores were considerably below that of the Mental Component Summary (MCS) score at baseline and at all following time points. Carers described the physical effort associated with patient care and role change; the challenge inherent in having time away; and problems relating to the timing of equipment and service delivery. CONCLUSIONS NIV can be recommended to patients without concerns regarding increasing carer burden. The predominant source of burden described related to the physical impact of caring for a patient with MND. Services face challenges if this physical burden is to be reduced by providing equipment at an optimal time and successfully coordinating their input.

Protocol for diaphragm pacing in patients with respiratory muscle weakness due to motor neurone disease (DiPALS): a randomised controlled trial.

BackgroundMotor neurone disease (MND) is a devastating illness which leads to muscle weakness and death, usually within 2-3 years of symptom onset. Respiratory insufficiency is a common cause of morbidity, particularly in later stages of MND and respiratory complications are the leading cause of mortality in MND patients. Non Invasive Ventilation (NIV) is the current standard therapy to manage respiratory insufficiency. Some MND patients however do not tolerate NIV due to a number of issues including mask interface problems and claustrophobia. In those that do tolerate NIV, eventually respiratory muscle weakness will progress to a point at which intermittent/overnight NIV is ineffective. The NeuRx RA/4 Diaphragm Pacing System was originally developed for patients with respiratory insufficiency and diaphragm paralysis secondary to stable high spinal cord injuries. The DiPALS study will assess the effect of diaphragm pacing (DP) when used to treat patients with MND and respiratory insufficiency.Method/Design108 patients will be recruited to the study at 5 sites in the UK. Patients will be randomised to either receive NIV (current standard care) or receive DP in addition to NIV. Study participants will be required to complete outcome measures at 5 follow up time points (2, 3, 6, 9 and 12 months) plus an additional surgery and 1 week post operative visit for those in the DP group. 12 patients (and their carers) from the DP group will also be asked to complete 2 qualitative interviews.DiscussionThe primary objective of this trial will be to evaluate the effect of Diaphragm Pacing (DP) on survival over the study duration in patients with MND with respiratory muscle weakness. The project is funded by the National Institute for Health Research, Health Technology Assessment (HTA) Programme (project number 09/55/33) and the Motor Neurone Disease Association and the Henry Smith Charity. Trial Registration: Current controlled trials ISRCTN53817913. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HTA programme, NIHR, NHS or the Department of Health.

Incremental shuttle walk test in the assessment of patients with obstructive sleep apnea–hypopnea syndrome

Obstructive sleep apnea–hypopnea syndrome is associated independently with an increase in cardiovascular risk factors and is associated with self‐reported lack of exercise. We aimed to investigate the utility of the incremental shuttle walk test in routine clinical practice to monitor physical capacity of patients with obstructive sleep apnea–hypopnea syndrome and explore whether continuous positive airway pressure therapy alters exercise capacity. Participants with symptomatic moderate/severe obstructive sleep apnea–hypopnea syndrome attending for a trial of continuous positive airway pressure therapy completed questionnaires assessing sleepiness and physical activity and underwent an incremental shuttle walk test. Subjects compliant or partially compliant with continuous positive airway pressure therapy underwent reassessment at 2 weeks, 3 months and 6 months post‐initiation of therapy. Participants unable to tolerate continuous positive airway pressure therapy completed a single reassessment 6 months after their initial visit. Continuous positive airway pressure therapy resulted in an increased distance walked during the incremental shuttle walk test. Improvements in cardiovascular responses to exercise were identified. Compliant patients reported increased daily activity. The incremental shuttle walk test is a simple, reproducible and safe test that is responsive to continuous positive airway pressure treatment. Our findings support the use of the incremental shuttle walk test for monitoring the effects of continuous positive airway pressure treatment and may suggest its use in rehabilitation programmes designed to reduce obesity and cardiovascular risk factors in patients with obstructive sleep apnea–hypopnea syndrome.