Seronegative Mediastinal Coccidioidomycosis as a Novel Presentation of CTPS1 Combined Immunodeficiency

The Known and Unknown "Knowns" of Human Susceptibility to Coccidioidomycosis

Coccidioidomycosis occurs after inhalation of airborne spores of the endemic, dimorphic fungus, Coccidioides. While the majority of individuals resolve the infection without coming to medical attention, the fungus is a major cause of community-acquired pneumonia in the endemic region, and chronic pulmonary and extrapulmonary disease poses significant personal and economic burdens. This review explores the literature surrounding human susceptibility to coccidioidomycosis, including chronic pulmonary and extrapulmonary dissemination. Over the past century of study, themes have emerged surrounding factors impacting human susceptibility to severe disease or dissemination, including immune suppression, genetic susceptibility, sex, pregnancy, and genetic ancestry. Early studies were observational, frequently with small numbers of cases; several of these early studies are highly cited in review papers, becoming part of the coccidioidomycosis "canon". Specific genetic variants, sex, and immune suppression by TNF inhibitors have been validated in later cohort studies, confirming the original hypotheses. By contrast, some risk factors, such as ABO blood group, Filipino ancestry, or lack of erythema nodosum among black individuals, are repeated in the literature despite the lack of supporting studies or biologic plausibility. Using examination of historical reports coupled with recent cohort and epidemiology studies, evidence for commonly reported risk factors is discussed.

When to suspect inborn errors of immunity in Epstein-Barr virus-related lymphoproliferative disorders

BACKGROUND

More than 95% of humans have been infected with Epstein-Barr virus (EBV) and develop anti-EBV IgG antibodies, conferring immunity. However, among specific populations, EBV may induce a range of B-cell lymphoproliferative disorders (LPDs). EBV may also contribute to T-cell and natural killer (NK)-cell lymphoproliferation. The immune system is essential to prevent infection and development of cancer. Inborn errors of immunity (IEIs) are a heterogenous group of more than 450 genetic disorders predisposing to severe and/or recurrent infection, autoimmunity, autoinflammation, or early-onset/severe neoplasia or lymphoproliferation. Monogenic disorders of T-cell and B-cell signalling are classic IEIs that predispose to EBV-associated LPDs.

OBJECTIVES

We aimed to outline the various clinical manifestations of EBV-associated LPDs and the underlying IEIs associated with such presentations and discuss the recommended management and therapeutic options pertaining to these disorders.

SOURCES

We searched PubMed, Embase, and Web of Science Core Collection on 30 September 2021. Clinical studies, systematic reviews, narrative reviews, and case reports were identified through search strategy and cross reference from primary literature.

CONTENT

Effective T-cell and NK-cell cytotoxicity towards EBV-infected B cells relies on intact MAGT1-dependent NKG2D pathways and signalling lymphocyte activation molecular-associated protein-dependent signalling lymphocyte activation molecular receptors. The interaction between CD27 and CD70 is also critical to drive the expansion of EBV-specific T cells. IEIs due to T-cell and B-cell signalling defects and/or impaired T-cell and NK-cell cytotoxicity predispose to EBV-related lymphoproliferation. This includes classic disorders such as X-linked lymphoproliferative disease 1 (due to SH2D1A mutations), X-linked lymphoproliferative disease 2 (XIAP), and other genetic diseases, such as ITK, MAGT1, CD27, CD70, CTPS1, RASGRP1, and CORO1A deficiencies. EBV-driven lymphoproliferation may manifest to a lesser degree in MST1/STK4, DOCK8, STIM1, CORO1A, IL21R, PIK3CD gain-of-function, and PI3KR1 deficiencies.

IMPLICATIONS

Early screening for IEIs is indicated in cases of EBV-related lymphoproliferation because different forms of IEIs have specific prognostic and therapeutic implications.

Inborn Errors of Immunity Causing Pediatric Susceptibility to Fungal Diseases

Inborn errors of immunity are a heterogeneous group of genetically determined disorders that compromise the immune system, predisposing patients to infections, autoinflammatory/autoimmunity syndromes, atopy/allergies, lymphoproliferative disorders, and/or malignancies. An emerging manifestation is susceptibility to fungal disease, caused by yeasts or moulds, in a superficial or invasive fashion. In this review, we describe recent advances in the field of inborn errors of immunity associated with increased susceptibility to fungal disease.

Granulomatous inflammation in inborn errors of immunity

Granulomas have been defined as inflammatory infiltrates formed by recruitment of macrophages and T cells. The three-dimensional spherical structure typically consists of a central core of tissue resident macrophages which may merge into multinucleated giant cells surrounded by T cells at the periphery. Granulomas may be triggered by infectious and non-infectious antigens. Cutaneous and visceral granulomas are common in inborn errors of immunity (IEI), particularly among patients with chronic granulomatous disease (CGD), combined immunodeficiency (CID), and common variable immunodeficiency (CVID). The estimated prevalence of granulomas in IEI ranges from 1%-4%. Infectious agents causing granulomas such Mycobacteria and Coccidioides presenting atypically may be 'sentinel' presentations for possible underlying immunodeficiency. Deep sequencing of granulomas in IEI has revealed non-classical antigens such as wild-type and RA27/3 vaccine-strain Rubella virus. Granulomas in IEI are associated with significant morbidity and mortality. The heterogeneity of granuloma presentation in IEI presents challenges for mechanistic approaches to treatment. In this review, we discuss the main infectious triggers for granulomas in IEI and the major forms of IEI presenting with 'idiopathic' non-infectious granulomas. We also discuss models to study granulomatous inflammation and the impact of deep-sequencing technology while searching for infectious triggers of granulomatous inflammation. We summarize the overarching goals of management and highlight the therapeutic options reported for specific granuloma presentations in IEI.