A New Patient with p40phox Deficiency and Chronic Immune Thrombocytopenia

Standardization of the use of opsonized zymosan as stimulus in the 1,2,3-dihydrorhodamine technique for the assessment of neutrophil respiratory burst

Introduction

Chronic granulomatous disease is a defect in phagocytosis due to deficiency of gp91phox, p22phox, p47phox, p40phox, and p67phox (classic form of the disease). Recently, EROS and p40phox deficiency were described as responsible for the non-classical form of the disease. The 1,2,3-dihydrorhodamine oxidation technique, with phorbol-12-myristate-13-acetate as a stimulus, is performed to diagnose the classic chronic granulomatous disease. However, oxidation mediated by EROS and p40phox requires stimuli such as zymosan, Escherichia coli, or Staphylococcus aureus.

Objective

To optimize the 1,2,3-dihydrorhodamine technique using zymosan to assess neutrophil respiratory burst and detect the non-classical chronic granulomatous disease.

Materials and method

Blood was obtained from five healthy subjects after the signature of the informed consent. The 1,2,3-dihydrorhodamine technique was performed with phorbol-12-myristate-13-acetate as control and different quantities of opsonized zymosan (150, 100, 50, 20, and 10 μg). We obtained through flow cytometry the mean fluorescence intensity of rhodamine 1,2,3 oxidated in the neutrophil population and calculated the oxidation index. The Kolmogorov-Smirnov test, ANOVA, and Tukey’s post-hoc analysis were used. We considered a p value ≤ 0.05 as statistically significant.

Results

The phorbol-12-myristate-13-acetate increased the rhodamine 1,2,3 mean fluorescence intensity in healthy subjects. Among the different zymosan conditions tested, we selected 50 μg as the optimal and reproducible amount in all controls according to the statistical analysis and cytometric findings.

Conclusions

We present the optimization of the 1,2,3-dihydrorhodamine technique using zymosan. We propose its implementation in clinical diagnostic laboratories to expand the diagnosis of chronic granulomatous disease.

Case Report: p40 phox deficiency underlying pediatric-onset systemic lupus erythematosus

Introduction

Systemic lupus erythematosus is a multi-faceted autoimmune disorder of complex etiology. Pre-pubertal onset of pediatric systemic lupus erythematosus (pSLE) is uncommon and should raise suspicion for a genetic driver of disease. Autosomal recessive p40 phox deficiency is a rare immunologic disorder characterized by defective but not abolished NADPH oxidase activity with residual production of reactive oxygen species (ROS) by phagocytic cells.

Case presentation

We report the case of a now 18-year-old female with pSLE onset at 7 years of age. She presented with recurrent fever and malar rash. Aspects of her immune dysregulation over time have included typical pSLE features including production of autoantibodies, hematologic manifestations, and hypocomplementemia, as well as chronic suppurative skin lesions and recurrent infections. Genetic analysis revealed biallelic pathogenic variants in NCF4 resulting in p40 phox deficiency. Comprehensive NADPH oxidase activity studies confirmed significantly decreased production of reactive oxygen species, confirming the cellular phenotype seen in p40 phox deficient patients.

Conclusions

Here, we present a patient with pSLE harboring biallelic variants in NCF4. Our patient represents a unique clinical presentation of severe onset autoimmunity in the setting of a rare inborn error of immunity affecting NADPH oxidase activity. This case underscores the need to consider genetic causes of pSLE in cases of pre-pubertal onset and atypical disease.

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.

From Mendel to mycoses: Immuno-genomic warfare at the human-fungus interface

Fungi are opportunists: They particularly require a defect of immunity to cause severe or disseminated disease. While often secondary to an apparent iatrogenic cause, fungal diseases do occur in the absence of one, albeit infrequently. These rare cases may be due to an underlying genetic immunodeficiency that can present variably in age of onset, severity, or other infections, and in the absence of a family history of disease. They may also be due to anti-cytokine autoantibodies. This review provides a background on how human genetics or autoantibodies underlie cases of susceptibility to severe or disseminated fungal disease. Subsequently, the lessons learned from these inborn errors of immunity marked by fungal disease (IEI-FD) provide a framework to begin to mechanistically decipher fungal syndromes, potentially paving the way for precision therapy of the mycoses.