A novel mutation in EROS (CYBC1) causes chronic granulomatous disease.

Chronic Granulomatous Disease (CGD) is an inborn error of immunity characterised by opportunistic infection and sterile granulomatous inflammation. CGD is caused by a failure of reactive oxygen species (ROS) production by the phagocyte NADPH oxidase. Mutations in the genes encoding phagocyte NADPH oxidase subunits cause CGD. We and others have described a novel form of CGD (CGD5) secondary to lack of EROS (CYBC1), a highly selective chaperone for gp91phox. EROS-deficient cells express minimal levels of gp91phox and its binding partner p22phox, but EROS also controls the expression of other proteins such as P2X7. The full nature of CGD5 is currently unknown. We describe a homozygous frameshift mutation in CYBC1 leading to CGD. Individuals who are heterozygous for this mutation are found in South Asian populations (allele frequency = 0.00006545), thus it is not a private mutation. Therefore, it is likely to be the underlying cause of other cases of CGD.

An open source pipeline for quantitative immunohistochemistry image analysis of inflammatory skin disease using artificial intelligence.

BACKGROUND: The application of artificial intelligence (AI) to whole slide images has the potential to improve research reliability and ultimately diagnostic efficiency and service capacity. Image annotation plays a key role in AI and digital pathology. However, the work-streams required for tissue-specific (skin) and immunostain-specific annotation has not been extensively studied compared with the development of AI algorithms. OBJECTIVES: The objective of this study is to develop a common workflow for annotating whole slide images of biopsies from inflammatory skin disease immunostained with a variety of epidermal and dermal markers prior to the development of the AI-assisted analysis pipeline. METHODS: A total of 45 slides containing 3-5 sections each were scanned using Aperio AT2 slide scanner (Leica Biosystems). These slides were annotated by hand using a commonly used image analysis tool which resulted in more than 4000 images blocks. We used deep learning (DL) methodology to first sequentially segment (epidermis and upper dermis), with the exclusion of common artefacts and second to quantify the immunostained signal in those two compartments of skin biopsies and the ratio of positive cells. RESULTS: We validated two DL models using 10-fold validation runs and by comparing to ground truth manually annotated data. The models achieved an average (global) accuracy of 95.0% for the segmentation of epidermis and dermis and 86.1% for the segmentation of positive/negative cells. CONCLUSIONS: The application of two DL models in sequence facilitates accurate segmentation of epidermal and dermal structures, exclusion of common artefacts and enables the quantitative analysis of the immunostained signal. However, inaccurate annotation of the slides for training the DL model can decrease the accuracy of the output. Our open source code will facilitate further external validation across different immunostaining platforms and slide scanners.

EROS is a selective chaperone regulating the phagocyte NADPH oxidase and purinergic signalling.

EROS (essential for reactive oxygen species) protein is indispensable for expression of gp91phox, the catalytic core of the phagocyte NADPH oxidase. EROS deficiency in humans is a novel cause of the severe immunodeficiency, chronic granulomatous disease, but its mechanism of action was unknown until now. We elucidate the role of EROS, showing it acts at the earliest stages of gp91phox maturation. It binds the immature 58 kDa gp91phox directly, preventing gp91phox degradation and allowing glycosylation via the oligosaccharyltransferase machinery and the incorporation of the heme prosthetic groups essential for catalysis. EROS also regulates the purine receptors P2X7 and P2X1 through direct interactions, and P2X7 is almost absent in EROS-deficient mouse and human primary cells. Accordingly, lack of murine EROS results in markedly abnormal P2X7 signalling, inflammasome activation, and T cell responses. The loss of both ROS and P2X7 signalling leads to resistance to influenza infection in mice. Our work identifies EROS as a highly selective chaperone for key proteins in innate and adaptive immunity and a rheostat for immunity to infection. It has profound implications for our understanding of immune physiology, ROS dysregulation, and possibly gene therapy.