Thoracic Surgery in Chronic Granulomatous Disease: a 25-Year Single-Institution Experience

Introduction

Chronic granulomatous disease (CGD) is a genetic disorder in which phagocyte dysfunction leads to recurrent infection. Persistent pulmonary infections sometimes require thoracic surgical intervention. We reviewed our 25-year experience to identify outcomes and prognostic factors associated with thoracic surgery in these patients.

Methods

A retrospective single-institution review of all patients with CGD from 1990 through 2015 was performed. Univariate analysis identified prognostic variables to include in a Cox model. Overall survival was estimated by the Kaplan-Meier method.

Results

We identified 258 patients who had 2221 admissions (both scheduled and emergent). During the period examined, 51 thoracic operations were performed in 13.6 % (35/258) of patients and 2.3 % (35/2221) of overall admissions. Patients undergoing surgery did not have statistically significant differences in disease genotype compared to those that did not require surgery. Pathogens were identified from 67 % (34/51) of specimens. Complications occurred in 27 % (14/51), including 10 % (5/51) with wound and 12 % (6/51) with pulmonary infections. Mortality at 30 and 90 days was 0 and 6 % (3/51), respectively. Overall survival probabilities were 75 and 62 % at 5- and 10-year follow-up (median potential follow-up: 16.5 years), respectively. Undergoing thoracic surgery was associated with an increased hazard ratio for death of 3.71 (p?<?0.0001). Both chest wall resection and EBL?>?500 mL were negative prognostic factors (p?<?0.05).

Conclusions

A minority of CGD patients required thoracic surgery for infections refractory to antibiotic or antifungal therapy. Patients who had these operations had significant morbidity and relatively poor long-term survival, particularly in the cases of chest wall resection or significant blood loss.

     

An AAVS1-Targeted Minigene Platform for Correction of iPSCs From All Five Types of Chronic Granulomatous Disease

There are five genetic forms of chronic granulomatous disease (CGD), resulting from mutations in any of five subunits of phagocyte oxidase, an enzyme complex in neutrophils, monocytes, and macrophages that produces microbicidal reactive oxygen species. We generated induced pluripotent stem cells (iPSCs) from peripheral blood CD34⁺ hematopoietic stem cells of patients with each of five CGD genotypes. We used zinc finger nuclease (ZFN) targeting the AAVS1 safe harbor site together with CGD genotype-specific minigene plasmids with flanking AAVS1 sequence to target correction of iPSC representing each form of CGD. We achieved targeted insertion with constitutive expression of desired oxidase subunit in 70–80% of selected iPSC clones. Neutrophils and macrophages differentiated from corrected CGD iPSCs demonstrated restored oxidase activity and antimicrobial function against CGD bacterial pathogens Staphylococcus aureus and Granulibacter bethesdensis. Using a standard platform that combines iPSC generation from peripheral blood CD34⁺ cells and ZFN mediated AAVS1 safe harbor minigene targeting, we demonstrate efficient generation of genetically corrected iPSCs using an identical approach for all five genetic forms of CGD. This safe harbor minigene targeting platform is broadly applicable to a wide range of inherited single gene metabolic disorders.     

Host Defense Functions of Proteolytically Processed and Parent (Unprocessed) Cathelicidins of Rabbit Granulocytes

Members of the cathelicidin family are present in all mammals studied. Generally, these proteins contain a conserved N-terminal domain and a structurally and functionally divergent C-terminal region that expresses antibacterial or other activities when proteolytically released. Rabbit granulocytes produce CAP18, a cathelicidin that conforms to this structural and functional organization, and also 15-kDa protein isoforms (p15s) that share several key structural features with other cathelicidins but apparently do not undergo processing with release of an active peptide. To further define the importance of proteolysis in the antibacterial activities of these proteins, we have purified from granulocytes proCAP18, its C-terminal peptide (CAP18p), and two p15 isoforms to apparent homogeneity. Of these four polypeptides, only CAP18p was independently cytotoxic to encapsulated Escherichia coli (90% inhibitory concentration, approximately 600 nM) but it was approximately 50-fold less potent on a molar basis than the bactericidal/permeability-increasing protein (BPI). However, all four cathelicidin species, notably including proCAP18, exhibited antibacterial synergy with BPI, and the p15s also displayed synergy with CAP18p in the absence of BPI. Subnanomolar concentrations of proCAP18 blocked lipopolysaccharide-induced chemiluminescence of human leukocytes, showing a molar potency more than 100-fold greater than that of CAP18p ( approximately 20 nM) or BPI ( approximately 50 nM). Thus, while independent bactericidal activity of cathelicidins requires processing, other host-defense functions do not and are more potently expressed by the unprocessed protein than by the C-terminal peptide.     

Chronic granulomatous disease: overview and hematopoietic stem cell transplantation

Chronic granulomatous disease (CGD) still causes significant morbidity and mortality. The difficulty in considering high-risk yet curative treatments, such as allogeneic bone marrow transplantation, lies in the unpredictable courses of both CGD and bone marrow transplantation in different patients. Some patients with CGD can have frequent infections, granulomatous or autoimmune disorders necessitating immunosuppressive therapy, or both but also experience long periods of relative good health. However, the risk of death is clearly higher in patients with CGD of all types, and the complications of CGD short of death can still cause significant morbidity. Therefore, with recent developments and improvements, bone marrow transplantation, previously considered an experimental or high-risk procedure, has emerged as an important option for patients with CGD. We will discuss the complications of CGD that result in significant morbidity and mortality, particularly the most common infections and autoimmune/inflammatory complications, as well as their typical management. We will then discuss the status of bone marrow transplantation.     

Innate immunity against Granulibacter bethesdensis, an emerging gram-negative bacterial pathogen

Acetic acid bacteria were previously considered nonpathogenic in humans. However, over the past decade, five genera of Acetobacteraceae have been isolated from patients with inborn or iatrogenic immunodeficiencies. Here, we describe the first studies of the interactions of the human innate immune system with a member of this bacterial family, Granulibacter bethesdensis, an emerging pathogen in patients with chronic granulomatous disease (CGD). Efficient phagocytosis of G. bethesdensis by normal and CGD polymorphonuclear leukocytes (CGD PMN) required heat-labile serum components (e.g., C3), and binding of C3 and C9 to G. bethesdensis was detected by immunoblotting. However, this organism survived in human serum concentrations of ≥90%, indicating a high degree of serum resistance. Consistent with the clinical host tropism of G. bethesdensis, CGD PMN were unable to kill this organism, while normal PMN, in the presence of serum, reduced the number of CFU by about 50% after a 24-h coculture. This finding, together with the observations that G. bethesdensis was sensitive to H(2)O(2) but resistant to LL-37, a human cationic antimicrobial peptide, suggests an inherent resistance to O(2)-independent killing. Interestingly, 10 to 100 times greater numbers of G. bethesdensis were required to achieve the same level of reactive oxygen species (ROS) production induced by Escherichia coli in normal PMN. In addition to the relative inability of the organism to elicit production of PMN ROS, G. bethesdensis inhibited both constitutive and FAS-induced PMN apoptosis. These properties of reduced PMN activation and resistance to nonoxidative killing mechanisms likely play an important role in G. bethesdensis pathogenesis.