Future of Care for Patients With Chronic Granulomatous Disease: Gene Therapy and Targeted Molecular Medicine

Clinical presentation, diagnosis, and treatment of chronic granulomatous disease

Chronic granulomatous disease (CGD) is caused by an impaired respiratory burst reaction in phagocytes. CGD is an X-linked (XL) (caused by pathogenic variants in CYBB) or autosomal recessive inborn error of immunity (caused by pathogenic variants in CYBA, NCF1, NCF2, or CYBC1). Female carriers of XL-CGD and unfavorable lyonization may present with the partial or full picture of CGD. Patients with CGD are at increased risk for invasive bacterial and fungal infections of potentially any organ, but especially the lymph nodes, liver, and lungs. Pathogens most frequently isolated are S. aureus and Aspergillus spp. Autoinflammation is difficult to control with immunosuppression, and patients frequently remain dependent on steroids. To diagnose CGD, reactive oxygen intermediates (O2 - or H2O2) generated by the NADPH oxidase in peripheral blood phagocytes are measured upon in vitro activation with either phorbol-12-myristate-13-acetate (PMA) and/or TLR4 ligands (E. coli or LPS). Conservative treatment requires strict hygienic conduct and adherence to antibiotic prophylaxis against bacteria and fungi, comprising cotrimoxazole and triazoles. The prognosis of patients treated conservatively is impaired: for the majority of patients, recurrent and/or persistent infections, autoinflammation, and failure to thrive remain lifelong challenges. In contrast, cellular therapies (allogeneic stem cell transplantation or gene therapy) can cure CGD. Optimal outcomes in cellular therapies are observed in individuals without ongoing infections or inflammation. Yet cellular therapies are the only curative option for patients with persistent fungal infections or autoinflammation.

Chronic Granulomatous Disease: an Updated Experience, with Emphasis on Newly Recognized Features

Purpose

Chronic granulomatous disease (CGD) is an uncommon, inborn error of immunity. We updated our large, single-center US experience with CGD and describe some newly recognized features.

Methods

We retrospectively reviewed 26 patients seen from November 2013 to December 2019. Serious infections required intravenous antibiotics or hospitalization.

Results

There were 21 males and 5 females. The most frequent infectious agents at presentation were aspergillus (4), serratia (4), burkholderia (2), Staphylococcus aureus (2), and klebsiella (2). The most common serious infections at presentation were pneumonia (6), lymphadenitis (6), and skin abscess (3). Our serious infection rate was 0.2 per patient-year from December 2013 through November 2019, down from 0.62 per patient-year from the previous study period (March 1985–November 2013). In the last 6 years, four patients were evaluated for human stem cell transplantation, two were successfully transplanted, and we had no deaths. Several patients had unusual infections or autoimmune manifestations of disease, such as pneumocystis pneumonia, basidiomycete/phellinus fungal pneumonia, and retinitis pigmentosa. We included one carrier female with unfavorable Lyonization in our cohort.

Conclusion

We update of a large US single-center experience with CGD and describe some recently identified features of the illness.

Effects of voriconazole on population pharmacokinetics and optimization of the initial dose of tacrolimus in children with chronic granulomatous disease undergoing hematopoietic stem cell transplantation

Background

This study aimed to explore the effects of voriconazole on population pharmacokinetics and optimization of the initial dose of tacrolimus in children with chronic granulomatous disease (CGD) undergoing hematopoietic stem cell transplantation (HSCT).

Methods

Thirty-four children with CGD undergoing HSCT were assessed to establish a population pharmacokinetic model (PPM) using the non-linear mixed effect. Tacrolimus concentrations were simulated by the Monte Carlo method in children weighing <25 kg at different doses.

Results

In the final model, weight and concomitant use of voriconazole were included as covariates. With the same weight, the relative value of tacrolimus clearance was 1:0.388 in children not taking voriconazole: children taking voriconazole. Compared with children not taking voriconazole, the measured tacrolimus concentrations were all higher in children taking voriconazole (P<0.01); however, these were not corrected by dose or body weight for concentration differences. Thus, we simulated the tacrolimus concentrations using different body weights (5–25 kg) and different dose regimens (0.1–0.8 mg/kg/day) for the same body weight and dose. Tacrolimus concentrations in children taking voriconazole were higher than those in children not taking voriconazole (P<0.01). Also, in children with CGD undergoing HSCT who were not taking voriconazole, the initial dose regimen of 0.5 mg/kg/day was recommended for body weights of 5–10 kg, and 0.4 mg/kg/day was recommended for body weights of 10–25 kg. In children with CGD undergoing HSCT who were taking voriconazole, an initial dose regimen of 0.3 mg/kg/day was recommended for body weights of 5–25 kg.

Conclusions

We established, for the first time, a PPM of tacrolimus in children with CGD undergoing HSCT in which voriconazole significantly increased tacrolimus concentrations. In addition, the initial dose of tacrolimus in children with CGD undergoing HSCT was recommended.

Characterization of dental pulp stem cells isolated from a patient diagnosed with Crouzon syndrome

Stem cells isolated from patients with rare diseases are important to elucidate their pathogeny and mechanisms to enable regenerative therapy. However, the mechanisms underlying tissue regeneration using patient‐derived dental pulp stem cells (DPSCs) are unclear. In this study, we investigated the levels of mRNA and protein expression related to cellular differentiation of Crouzon syndrome patient‐derived DPSCs (CS‐DPSCs) with a Gly338Arg fibroblast growth factor receptor 2 mutation. Multipotency‐related gene expression levels were equivalent in both healthy donor DPSCs and CS‐DPSCs. CS‐DPSCs showed higher osteocalcin (OCN) expression than healthy donor DPSCs. CS‐DPSCs showed a lower increase in the rate of OCN expression among phorbol 12‐myristate 13‐acetate (PMA)‐treated cells than healthy donor DPSCs compared with untreated control cells. CS‐DPSCs showed a lower phosphorylation rate of p38 and p44/42 in PMA‐treated cells than healthy donor DPSCs compared with untreated control cells. These results demonstrate that CS‐DPSCs have higher OCN expression and lower PMA stimulation‐responsiveness than healthy donor DPSCs.

NOX Inhibitors: From Bench to Naxibs to Bedside

Reactive oxygen species (ROS) are ubiquitous metabolic products and important cellular signaling molecules that contribute to several biological functions. Pathophysiology arises when ROS are generated either in excess or in cell types or subcellular locations that normally do not produce ROS or when non-physiological types of ROS (e.g., superoxide instead of hydrogen peroxide) are formed. In the latter scenario, antioxidants were considered as the apparent remedy but, clinically, have consistently failed and even sometimes induced harm. The obvious reason for that is the non-selective ROS scavenging effects of antioxidants which interfere with both qualities of ROS, physiological and pathological. Therefore, it is essential to overcome this "antidote or neutralizer" strategy. We here review the most promising alternative approach by identifying the disease-relevant enzymatic sources of ROS, target these selectively, but leave physiological ROS signaling through other sources intact. Among all ROS sources, NADPH oxidases (NOX1-5 and DUOX1-2) stand out as their sole function is to produce ROS, whereas most other enzymatic sources only produce ROS as a by-product or upon biochemical uncoupling or damage. This qualifies NOXs as the main potential drug-target candidates in diseases associated with dysfunction in ROS signaling. As a reflection of this, the development of several NOX inhibitors has taken place. Recently, the WHO approved a new stem, "naxib," which refers to NADPH oxidase inhibitors, and thereby recognized NOX inhibitors as a new therapeutic class. This has been announced while clinical trials with the first-in-class compound, setanaxib (initially known as GKT137831) had been initiated. We also review the differences between the seven NOX family members in terms of structure and function in health and disease and then focus on the most advanced NOX inhibitors with an exclusive focus on clinically relevant validations and applications. Therapeutically relevant NADPH oxidase isoforms type 1, 2, 4, and 5 (NOX1, NOX2, NOX4, NOX5). Of note, NOX5 is not present in mice and rats and thus pre-clinically less studied. NOX2, formerly termed gp91^phox, has been correlated with many, too many, diseases and is rather relevant as genetic deficiency in chronic granulomatous disease (CGD), treated by gene therapy. Overproduction of ROS through NOX1, NOX4, and NOX5 leads to the indicated diseases states including atherosclerosis (red), a condition where NOX4 is surprisingly protective.

Geographic Variability and Pathogen-Specific Considerations in the Diagnosis and Management of Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a rare but serious primary immunodeficiency with varying prevalence and rates of X-linked and autosomal recessive disease worldwide. Functional defects in the phagocyte nicotinamide adenine dinucleotide phosphate oxidase complex predispose patients to a relatively narrow spectrum of bacterial and fungal infections that are sometimes fastidious and often difficult to identify. When evaluating and treating patients with CGD, it is important to consider their native country of birth, climate, and living situation, which may predispose them to types of infections that are atypical to your routine practice. In addition to recurrent and often severe infections, patients with CGD and X-linked female carriers are also susceptible to developing many non-infectious complications including tissue granuloma formation and autoimmunity. The DHR-123 oxidation assay is the gold standard for making the diagnosis and it along with genetic testing can help predict the severity and prognosis in patients with CGD. Disease management focuses on prophylaxis with antibacterial, antifungal, and immunomodulatory medications, prompt identification and treatment of acute infections, and prevention of secondary granulomatous complications. While hematopoietic stem-cell transplantation is the only widely available curative treatment for patients with CGD, recent advances in gene therapy may provide a safer, more direct alternative.

Late diagnosis of chronic granulomatous disease

Modern era advancements in medical care, with improved treatment of infections, can result in delayed diagnosis of congenital immunodeficiencies. In this study we present a retrospective cohort of 16 patients diagnosed with Chronic Granulomatous Disease (CGD) at adulthood. Some of the patients had a milder clinical phenotype, but others had a classic phenotype with severe infectious and inflammatory complications reflecting a profoundly impaired neutrophil function. It is therefore of great importance to investigate the individual journey of each patient through different misdiagnoses and the threads which led to the correct diagnosis. Currently the recommended definitive treatment for CGD is hematopoietic stem cell transplantation (HSCT). Although survival of our patients to adulthood might argue against the need for early HSCT during infancy, we claim that the opposite is correct, as most of them grew to be severely ill and diagnosed at a stage when HSCT is debatable with potentially an unfavorable outcome. This cohort stresses the need to increase awareness of this severe congenital immunodeficiency among clinicians of different specialties who might be treating undiagnosed adult patients with CGD.

Lentiviral gene therapy rescues p47phox chronic granulomatous disease and the ability to fight Salmonella infection in mice

Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency disorder characterised by recurrent and often life-threatening infections and hyperinflammation. It is caused by defects of the phagocytic NADPH oxidase, a multicomponent enzyme system responsible for effective pathogen killing. A phase I/II clinical trial of lentiviral gene therapy is underway for the most common form of CGD, X-linked, caused by mutations in the gp91^phox subunit of the NADPH oxidase. We propose to use a similar strategy to tackle p47^phox-deficient CGD, caused by mutations in NCF1, which encodes the p47^phox cytosolic component of the enzymatic complex. We generated a pCCLCHIM-p47^phox lentiviral vector, containing the chimeric Cathepsin G/FES myeloid promoter and a codon-optimised version of the human NCF1 cDNA. Here we show that transduction with the pCCLCHIM-p47^phox vector efficiently restores p47^phox expression and biochemical NADPH oxidase function in p47^phox-deficient human and murine cells. We also tested the ability of our gene therapy approach to control infection by challenging p47^phox-null mice with Salmonella Typhimurium, a leading cause of sepsis in CGD patients, and found that mice reconstituted with lentivirus-transduced hematopoietic stem cells had a reduced bacterial load compared with untreated mice. Overall, our results potentially support the clinical development of a gene therapy approach using the pCCLCHIM-p47^phox vector.

Application of droplet digital PCR for the detection of vector copy number in clinical CAR/TCR T cell products

Background

Genetically engineered T cells have become an important therapy for B-cell malignancies. Measuring the efficiency of vector integration into the T cell genome is important for assessing the potency and safety of these cancer immunotherapies.

Methods

A digital droplet polymerase chain reaction (ddPCR) assay was developed and evaluated for assessing the average number of lenti- and retroviral vectors integrated into Chimeric Antigen Receptor (CAR) and T Cell Receptor (TCR)-engineered T cells.

Results

The ddPCR assay consistently measured the concentration of an empty vector in solution and the average number of CAR and TCR vectors integrated into T cell populations. There was a linear relationship between the average vector copy number per cell measured by ddPCR and the proportion of cells transduced as measured by flow cytometry. Similar vector copy number measurements were obtained by different staff using the ddPCR assay, highlighting the assays reproducibility among technicians. Analysis of fresh and cryopreserved CAR T and TCR engineered T cells yielded similar results.

Conclusions

ddPCR is a robust tool for accurate quantitation of average vector copy number in CAR and TCR engineered T cells. The assay is also applicable to other types of genetically engineered cells including Natural Killer cells and hematopoietic stem cells.

The extended understanding of chronic granulomatous disease

PURPOSE OF REVIEW

We briefly address the advances in genetics, pathophysiology, and phenotypes of chronic granulomatous disease (CGD). This is one of the most studied primary immunodeficiencies, which comprise mutations in genes encoding the different subunits of the NADPH oxidase system. Those mutations lead to defective reactive oxygen species production, and consequently a failure to eliminate pathogens.

RECENT FINDINGS

Patients with CGD are susceptible to fungal, bacterial, and parasitic infections. Other symptoms, as systemic adverse effects to BCG vaccine and hyperinflammation, are also important clinical conditions in this disease. This wide-ranging clinical spectrum of CGD comes from heterogeneity of mutations, X-linked-CGD or autosomal recessive inheritance, and diverse environmental pressure factors. Early accurate diagnosis and prompt treatment are necessary to diminish the consequences of the disease. The most used diagnostic tests are dihydrorhodamine, cytochrome c reduction, and luminol-enhanced chemiluminescence assay.

SUMMARY

The determination of mutations is essential for diagnosis confirmation and genetic counseling. CGD treatment usually includes prophylactic antibiotics and antifungals. Prophylactic recombinant human interferon-γ, immunosuppressors or immune modulators may be, respectively, indicated for preventing infections or inflammatory manifestations. Hematopoietic stem cell transplantation and gene therapy are currently the available options for curative treatment of CGD.

Era of Genomic Medicine: A Narrative Review on CRISPR Technology as a Potential Therapeutic Tool for Human Diseases

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) provides acquired immunity in microorganisms against exogenous DNA that may hinder the survival of the organism. Pioneering work by Doudna and Charpentier in 2012 resulted in the creation of the CRISPR/Cas9 genome editing tool on the basis of this concept. The aim of this was to create a rapid, efficient, and versatile genome-editing tool to facilitate genetic manipulation. The mechanism relies on two components: the RNA guide which acts as a sentinel and a Cas protein complex which functions as a highly precise molecular knife. The guide RNA can be modified to match a DNA sequence of interest in the cell and accordingly be used to rectify mutations that may otherwise cause disease. Within a few years following the development of the CRISPR/Cas9 tool, its usage has become ubiquitous. Its influence extends into many fields of biological sciences from biotechnology and biochemistry to molecular biology and biomedical sciences. The following review aims at shedding some light on to the applications of the CRISPR/Cas9 tool in the field of biomedical sciences, particularly gene therapy. An insight with relation to a few of the many diseases that are being tackled with the aid of the CRISPR/Cas9 mechanism and the trends, successes, and challenges of this application as a gene therapy are discussed in this review.

B subset cells in patients with chronic granulomatous disease in a Mexican population

INTRODUCTION

Chronic granulomatous disease (CGD) is a disorder of phagocyte function, characterized by pyogenic infections and granuloma formation caused by defects in NADPH oxidase complex activity. Although the effect of CGD mainly reflects the phagocytic compartment, B cell responses are also impaired in patients with CGD.

MATERIALS AND METHODS

Flow cytometric analysis was performed on peripheral blood samples from 35 CGD patients age-matched with healthy controls (HC). The target cells of our study were the naive (IgD+/CD27-), memory (IgD-/CD27+), and B1a (CD5+) cells. Immunoglobulins (Igs) were also measured. This study was performed in a Latin American cohort.

RESULTS

We found significantly higher levels of naive B cells and B1a cells, but lower levels of memory B cells were found in CGD patients compared to HC. There was no significant difference of cell percentages per inheritance type.

DISCUSSION

Our findings suggest that the deficiency of NADPH oxidase components can affect the differentiation of naive B cells to memory B cells. Consequently, memory cells will be low, which also influenced the expression of CD27 in memory B cells and as a result, the percentage of naive cells increases. An altered phenotype of B lymphocytes in CGD patients may contribute to the opportunistic infections and autoimmune disorders that are seen in this disease.

Chemical Tools for Targeted Amplification of Reactive Oxygen Species in Neutrophils

A number of chemical compounds are known, which amplify the availability of reactive oxygen species (ROS) in neutrophils both in vitro and in vivo. They can be roughly classified into NADPH oxidase 2 (NOX2)-dependent and NOX2-independent reagents. NOX2 activation is triggered by protein kinase C agonists (e.g., phorbol esters, transition metal ions), redox mediators (e.g., paraquat) or formyl peptide receptor (FPR) agonists (e.g., aromatic hydrazine derivatives). NOX2-independent mechanisms are realized by reagents affecting glutathione homeostasis (e.g., l-buthionine sulfoximine), modulators of the mitochondrial respiratory chain (e.g., ionophores, inositol mimics, and agonists of peroxisome proliferator-activated receptor γ) and chemical ROS amplifiers [e.g., aminoferrocene-based prodrugs (ABPs)]. Since a number of inflammatory and autoimmune diseases, as well as cancer and bacterial infections, are triggered or enhanced by aberrant ROS production in neutrophils, it is tempting to use ROS amplifiers as drugs for the treatment of these diseases. However, since the known reagents are not cell specific, their application for treatment likely causes systemic enhancement of oxidative stress, leading to severe side effects. Cell-targeted ROS enhancement can be achieved either by using conjugates of ROS amplifiers with ligands binding to receptors expressed on neutrophils (e.g., the GPI-anchored myeloid differentiation marker Ly6G or FPR) or by designing reagents activated by neutrophil function [e.g., phagocytic activity or enzymatic activity of neutrophil elastase (NE)]. Since binding of an artificial ligand to a receptor may trigger or inhibit priming of neutrophils the latter approach has a smaller potential for severe side effects and is probably better suitable for therapy. Here, we review current approaches for the use of ROS amplifiers and discuss their applicability for treatment. As an example, we suggest a possible design of neutrophil-specific ROS amplifiers, which are based on NE-activated ABPs.