Cystic fibrosis and AA amyloidosis: a survey in the French cystic fibrosis network

Renal AA amyloidosis: presentation, diagnosis, and current therapeutic options: a review

Amyloid A amyloidosis is thought to be the second most common form of systemic amyloidosis behind amyloidosis secondary to monoclonal Ig. It is the result of deposition of insoluble fibrils in the extracellular space of tissues and organs derived from the precursor protein serum amyloid A, an acute phase reactant synthesized excessively in the setting of chronic inflammation. The kidney is the most frequent organ involved. Most patients present with proteinuria and kidney failure. The diagnosis is made through tissue biopsy with involvement of the glomeruli in most cases, but also often of the vessels and the tubulointerstitial compartment. The treatment usually targets the underlying etiology and consists increasingly of blocking the inflammatory cascade of cytokines with interleukin-1 inhibitors, interleukin-6 inhibitors, and tumor necrosis factor-α inhibitors to reduce serum amyloid A protein formation. This strategy has also shown efficacy in cases where an underlying etiology cannot be readily identified and has significantly improved the prognosis of this entity. In addition, there has been increased interest at developing effective therapies able to clear amyloid deposits from tissues, albeit with mitigated results so far.

Infections and AA amyloidosis: An overview

BACKGROUND

Amyloidoses are a heterogeneous group of systemic diseases characterised by extracellular accumulation of insoluble amyloid fibrils derived from unfolded proteins. Inflammatory (AA) amyloidosis can complicate various inflammatory disorders that are associated with a sustained acute phase response and serum amyloid A (SAA) protein overproduction. Chronic infections were the first recognised cause of amyloidoses. However, with the better management of underlying diseases, the frequency of AA amyloidosis is decreasing.

PURPOSE

The aim of this overview was to discuss the several infections associated with AA amyloidosis and the relative frequency of infections as aetiological factors.

METHODS

A search of the literature was performed using the PubMed database using the MeSH terms "Amyloidosis" and "Infections," from inception to December 31st, 2019. Articles written in other languages than English or French were excluded.

RESULTS

The frequency of AA amyloidosis secondary to infections decreased from more than 50% to less than 20% after the 2000s, with a parallel increase in the frequency of AA amyloidosis secondary to inflammatory diseases and to an unknown cause.

CONCLUSION

Whereas new antibiotics have been developed and sanitary conditions are better, infections still represent 5%-30% of the causes of AA amyloidosis, including in developed countries. These data argue for better screening of chronic infections to prevent AA amyloidosis and the development of new strategies to manage recurrent infections.

Amyloidosis in cystic fibrosis

As the life expectancy of patients with cystic fibrosis has increased, greater attention has been paid towards the diagnosis and management of the longer term consequences of the condition. A recognised but rare complication of the disease is the development of secondary amyloidosis. Whilst deposition of amyloid protein has been reported in a high proportion of patients with cystic fibrosis at post-mortem [1] and Serum Amyloid A protein has been shown to correlate with disease activity and response to antibiotics [2], the manifestation of clinical disease remains extremely uncommon. The prognosis for patients with amyloid secondary to cystic fibrosis in published reports has been historically bleak [3-6], however there may be novel approaches in the era of biological therapies. The theoretical potential for an increase in the incidence of secondary amyloid amongst the population of cystic fibrosis patients who are experiencing much longer lifespans means that it is worthwhile to consider the condition and its possible treatments in more detail. We report a case and a review of the literature.

Acute and chronic non-pulmonary complications in adults with cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is a genetic disease that primarily affects the respiratory system and often leads to respiratory failure and premature death. Although pulmonary complications contribute to 85% of deaths, non-pulmonary complications are responsible for significant morbidity and mortality in adults with CF. Areas covered: This review summarizes acute and chronic non-pulmonary complications in CF patients, with emphasis on emerging complications and in the context of the current growth and aging of the CF adult population. It also addresses the potential benefits of CF transmembrane conductance regulator modulator therapy. Complications that occur after solid organ (e.g. lung and/or liver) transplantation have been excluded. The review is based on an extensive search of the available literature, using PubMed and international guidelines, and on the authors' clinical experience. Expert commentary: Acute non-pulmonary complications have been well described but should be recognized and managed carefully. Managing chronic non-pulmonary complications is an important and changing aspect of CF patient care, particularly with the emergence of novel complications in adults. Early detection of non-pulmonary complications is essential to the development of prevention and treatment strategies that aim to further improve the survival and health status of adult CF patients.

[Ageing with cystic fibrosis: Classical and emerging comorbidities in adults with cystic fibrosis]

Cystic fibrosis (CF) is a genetic disease with pulmonary involvement being predominant and often leading to respiratory failure and premature death. Non-pulmonary complications related to CF transmembrane conductance regulator (CFTR) defect are numerous and account for significant morbidity (exocrine pancreatic insufficiency, diabetes, CF-related liver disease, chronic sinusitis, osteoporosis). Improvement in patients' care led to a continuous increase in life expectancy, with a subsequent increase in the number of adult CF patients worldwide. Increased life expectancy comes with increased prevalence of CF-related comorbidities, but also with new emerging complications directly related to ageing (chronic kidney disease, cardiovascular risk factors, cancers). CFTR modulators might also contribute to modify the face of CF epidemiology and prognosis. Ageing with CF has become a challenge for CF patients and caregivers. This review summarizes classic and emerging comorbidities in the context of current growth and ageing of the CF population. It also addresses potential roles of CFTR modulators.

Update of literature from cystic fibrosis registries 2012-2015. Part 6: Epidemiology, nutrition and complications

Patient registries provide useful information to afford more knowledge on rare diseases like Cystic Fibrosis (CF). Twenty-two studies originating from national CF registries, focusing on demographics, survival, genetics, nutritional status, and non-pulmonary complications, were published between December 2011 and March 2015. The purpose of this review article is to examine these reports, aiming attention to the clinical characteristics of CF patients included in the registries, current, and estimated future epidemiological data, the role of gender gap, the increasing survival in different countries. Some studies offer insights into pubertal growth and non-pulmonary complications, such as liver disease, nephropathy, and cancer. Pediatr Pulmonol. 2017;52:390-398. © 2016 Wiley Periodicals, Inc.

Albumin-induced circular dichroism in Congo red: Applications for studies of amyloid-like fibril aggregates and binding sites

Congo red (CR), one of the most commonly used dyes for the identification of amyloid fibril aggregates, is also a ligand of native bovine serum albumin (BSA). Induced circular dichroism (ICD) is a phenomenon observed when a chiral compound induces chirality in an achiral one. Here, we study the spectral properties and analytical applications of ICD in Congo red provoked by its interaction with BSA. The complex BSA:CR displays a strong ICD spectrum with a positive band at 412 nm and two negative bands at 356 and 490 nm. The use of site I and site II albumin ligands as warfarin and ibuprofen, respectively, provoked different alterations in the Congo red ICD spectrum. The BSA binding sites were modified by oxidation and the ICD signal was sensitive to this alteration. The thermal treatment of the BSA:CR complex (30-90 °C) was monitored by ICD at 490 nm and showed a sigmoidal pattern typical of phase transition in proteins. The altered ICD spectrum is consistent with the formation of amyloid-like fibril aggregates in BSA, which was confirmed by thioflavin T and Rayleigh scattering assays. In conclusion, the ICD provoked by the binding of Congo red to albumin may represent a new spectroscopic technique for studying alterations in the structure of albumin regarding its binding sites and the formation of amyloid aggregates.