Abnormal pro-gly-pro pathway and airway neutrophilia in pediatric cystic fibrosis

BACKGROUND

Proline-glycine-proline (PGP) is a bioactive fragment of collagen generated by the action of matrix metalloproteinase-9 (MMP-9) and prolylendopeptidase (PE), and capable of eliciting neutrophil chemotaxis and epithelial remodelling. PGP is normally then degraded by leukotriene A₄ hydrolase (LTA₄H) to limit inflammation and remodelling. This study hypothesized that early and persistent airway neutrophilia in Cystic Fibrosis (CF) may relate to abnormalities in the PGP pathway and sought to understand underlying mechanisms.

METHODS

Broncho-alveolar lavage (BAL) fluid was obtained from 38 CF (9 newborns and 29 older children) and 24 non-CF children. BAL cell differentials and levels of PGP, MMP-9, PE and LTA₄H were assessed.

RESULTS

Whilst PGP was present in all but one of the older CF children tested, it was absent in non-CF controls and the vast majority of CF newborns. BAL levels of MMP-9 and PE were elevated in older children with CF relative to CF newborns and non-CF controls, correlating with airway neutrophilia and supportive of PGP generation. Furthermore, despite extracellular LTA₄H commonly being greatly elevated concomitantly with inflammation to promote PGP degradation, this was not the case in CF children, potentially owing to degradation by neutrophil elastase.

CONCLUSIONS

A striking imbalance between PGP-generating and -degrading enzymes enables PGP accumulation in CF children from early life and potentially supports airway neutrophilia.

Pseudomonas aeruginosa infection in cystic fibrosis: pathophysiological mechanisms and therapeutic approaches

Pseudomonas aeruginosa is a remarkably versatile environmental bacterium with an extraordinary capacity to infect the cystic fibrosis (CF) lung. Infection with P. aeruginosa occurs early, and although eradication can be achieved following early detection, chronic infection occurs in over 60% of adults with CF. Chronic infection is associated with accelerated disease progression and increased mortality. Extensive research has revealed complex mechanisms by which P. aeruginosa adapts to and persists within the CF airway. Yet knowledge gaps remain, and prevention and treatment strategies are limited by the lack of sensitive detection methods and by a narrow armoury of antibiotics. Further developments in this field are urgently needed in order to improve morbidity and mortality in people with CF. Here, we summarize current knowledge of pathophysiological mechanisms underlying P. aeruginosa infection in CF. Established treatments are discussed, and an overview is offered of novel detection methods and therapeutic strategies in development.

New drug developments in the management of cystic fibrosis lung disease

INTRODUCTION

Therapies for cystic fibrosis (CF) pulmonary disease have, until recently, all targeted downstream manifestations rather than the root cause of the disease. A step-change in our approach has been achieved in the last few years, with novel small-molecule CFTR modulating drugs entering the clinic.

AREAS COVERED

In this article, we will discuss the field of drug development for CF lung disease. The case will be made for the potential benefits of basic defect-targeted strategies, which will be described in detail. Novel therapies directed at the downstream pulmonary manifestations of CF - infection, inflammation, and mucus impaction - will be reviewed. Finally, we will speculate on future directions and challenges.

EXPERT OPINION

CF drug development is in an exciting phase, catalysed by the impressive results seen in patients with ivacaftor-responsive CFTR mutations. The research field is active with trials of novel therapies targeting the basic defect, alongside drugs targeting downstream effects. In order to detect potentially small improvements due to novel therapies, especially in the context of treating young patients with early disease, sensitive outcome measures and the coordinated efforts of collaborative research networks are crucial.

A case of congenital central hypoventilation syndrome in a three-generation family with non-polyalanine repeat PHOX2B mutation

We describe a three generation family in whom multiple individuals are variably affected due to a PHOX2B non-polyalanine repeat mutation. This family demonstrates extreme phenotypic variability and autosomal dominant transmission over three generations not previously reported in the wider literature. Novel findings also inclue a history of recurrent second trimester miscarriage. Pediatr Pulmonol. 2014; 49:E140-E143. © 2014 Wiley Periodicals, Inc.

Experimental pancreatic cancer in the Syrian hamster: effect of cholecystectomy

Because cholecystectomy stimulates hypertrophy and hyperplasia in the hamster pancreas, its effect on experimental pancreatic carcinogenesis was studied in this animal model. Forty female Syrian hamsters underwent cholecystectomy, while 40 others underwent sham operations. Two weeks later, 30 hamsters undergoing cholecystectomy and 30 hamsters undergoing sham operations received 4 weekly subcutaneous injections of N-nitroso-bis (2-oxopropyl) amine (BOP) (10 mg/kg). Remaining hamsters (n = 20) received equal volumes of 0.9% saline solution. A further 10 hamsters (controls) underwent no surgery and received no injections. Thirty weeks after the first BOP or saline injection the pancreas of hamsters that had undergone cholecystectomy was only 3% heavier than that of sham-operated animals, and there was no difference in the incidence of pancreatic cancer between BOP-treated hamsters that had undergone cholecystectomy and those that had undergone sham operations. In this study, cholecystectomy had no influence on BOP-induced pancreatic carcinogenesis in the Syrian hamster.

Partial amputations of the foot for diabetic gangrene

Over a 5-year period 68 diabetic patients underwent 102 primary partial amputations of the foot for infected diabetic gangrene. Seventy (69%) of these operations healed without further local surgery, but five patients needed seven femoropopliteal bypass grafts (two bilateral) to achieve healing. In total, 32 primary operations needed revision by further surgery to the foot or by leg amputation. Of the original operations 31% were carried out by a consultant surgeon; the rest (69%) were performed by a junior surgeon. By contrast, only four of the 32 operations needing revision (12%) had originally been done by a consultant, whereas 28/32 (88%) had been carried out by a junior surgeon. Of limbs at risk 65/80 (81%) were salvaged. Five patients died during their hospital admission, giving an overall mortality of 7%.

Intestinal obstruction by overdistension of a jejunostomy catheter balloon: a salutary lesson

Jejunostomy is an alternative method for feeding patients who cannot be fed orally. However, there may be an associated morbidity and potential mortality. In the case presented, overdistension of a jejunostomy catheter balloon led to intestinal obstruction and pressure necrosis (of the small bowel), with subsequent abscess formation leading to death from septicemia.

Arterioenteric fistulas

Any patient with an abdominal aortic aneurysm, aortic graft or previously resected infected graft who presents with gastrointestinal bleeding or sepsis must be assumed to have an arterioenteric fistula. Warning bleeds are common. Oesophagogastroduodenoscopy may be diagnostic and should exclude other causes of upper gastrointestinal haemorrhage. Urgent investigation and surgery are essential for a successful outcome.

Secondary arterio-enteric fistulae: a surgical challenge

Ten cases of secondary arterio-enteric fistulae are described. There were nine graft enteric fistulae and one fistula involving the aortic suture line following elective resection of an infected graft. Only four of the patients initially received prophylactic antibiotics (single dose) at the original aortic reconstruction, and the vascular suture line had only been protected in two. Eight patients presented with bleeding and two with groin abscesses. One patient died before operation. Graft resection was undertaken in all patients and organisms were grown from six of eight grafts cultured. No patient died during operation but one died after 3 days. Axillofemoral bypass grafts were constructed in seven patients (four immediately after resection of prosthetic grafts and three within 4 days of operation). Only three of the eight patients who survived operation are still alive; two died of a ruptured aorta and one from a recurrent fistula. Two patients died of other causes. Four of five axillofemoral grafts in surviving patients subsequently occluded.

Interstitial emphysema of the stomach

A case of interstitial emphysema of the stomach is reported and the possible aetiological factors involved are discussed.

Treatment of early breast cancer

The early follow-up of patients treated by simple mastectomy alone or simple mastectomy combined with radical radiotherapy is presented. Both groups were well matched for age, menopausal status, duration of symptoms, size of tumour, and lymph-node involvement. There was no significant difference in survival of patients in the two groups at three years, but local recurrence was significantly more frequent (28%) in the mastectomy-alone patients. Early survival was not adversely affected by radiotherapy.

Ischaemic colitis and drug abuse

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Horizontal studies of cell mediated immune reactions to autologous tumour antigens in patients with operable mammary carcinoma

The leucocyte migration and guinea-pig macrophage migration procedures were used to assess cell mediated, tumour directed immune reactions in patients with mammary carcinoma undergoing simple mastectomy with or without post-operative irradiation. Forty-seven per cent of patients reacted to autologous tumour antigens and 40% to allogeneic antigens when tested 7 days after operation; 23% reacted to autologous antigens at 2 months, 19% at 6 months and 34% at 1 year after surgery. Reactions to benign tissue fractions were rare. Better discrimination between test and control subjects was obtained when 3000 g sediments rather than nuclei-depleted homogenates (extracts) were used. Irradiation 3-7 weeks post-operatively did not depress the in vitro response at 2 months and yielded a higher rate of positive reactions at 6 months. Correlations of serial LMT responses with certain clinical findings are discussed.

Depression of immunological responses due to surgery. A model in the guinea-pig

The responses of guinea-pigs to in vivo sensitization immediately following cholecystectomy (as a standard surgical procedure) are significantly depressed. Generation of memory function on stimulation with sheep erythrocytes is radically impaired; the effect is also more marked in primary delayed hypersensitivity and thymus-dependent antibody responses than in the response to pneumococcal polysaccharide. Normal lymphocyte transfer tests using operated animals as recipients or donors are not depressed. The evidence is suggestive of dysfunction in the amplification or co-operative stages of immune responses in the early post-operative period.

Multiple false localizing signs in intracranial tumor. Case report

✓ A case of cerebellar hemangioblastoma is presented in which multiple false localizing signs caused difficulty in the clinical localization of the lesion. The mode of presentation and pathogenesis of these signs are briefly discussed, and the observation made that the ninth and tenth cranial nerve palsies recorded in this case rarely lead to false localization.

Automation of the Wassermann complement-fixation test using a discrete analyser

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