Search

Adenosine deaminase 2 deficiency (DADA2) is a genetic auto- inflammatory disease that most often presents in childhood, but that can also have a late onset in adulthood. It is characterized by vasculitis, mainly of the skin and nervous system most often in the form of a stroke, associated to immunodeficiency and cytopenias. The diagnosis is made by measuring adenosine deaminase 2 (ADA2) enzymatic activity and confirming the presence of mutations in the ADA2 gene by genetic testing. The treatment of choice for the inflammatory phenotype is the early administration of anti-TNFa to avoid the risk of major neurological disabilities. In the case of severe hematological involvement, hematopoietic stem cell transplantation is the only curative treatment currently available.

Children appeared to be initially spared by the SARS-CoV-2 pandemic, however, in spring 2020, a new clinical entity was described related to the SARS-CoV-2 infection and named multisystem inflammatory syndrome in children (MIS-C) or pediatric inflammatory multisystem syndrome (PIMS). The gravity of this inflammatory syndrome, the time interval between infection and MIS-C, the response to the various immunomodulatory treatments are all suggestive of an immunologic reaction rather than a virus-mediatred phenomenon. The pathophysiological mechanisms and possible risk factors for MIS-C have not been elucidated. In this article, we summarize what is known to date about the immune response to SARS-CoV-2 in children and about the immune response to SARS-CoV-2 in children and about the MIS-C.

With the expansion of our knowledge on inborn errors of immunity (IEI), it gradually becomes clear that immune dysregulation plays an important part. In some cases, autoimmunity, hyperinflammation and lymphoproliferation are far more serious than infections. Thus, immune dysregulation has become significant in disease monitoring and treatment. In recent years, the wide application of whole-exome sequencing/whole-genome sequencing has tremendously promoted the discovery and further studies of new IEI. The number of discovered IEI is growing rapidly, followed by numerous studies of their pathogenesis and therapy. In this review, we focus on novel discovered primary immune dysregulation diseases, including deficiency of SLC7A7, CD122, DEF6, FERMT1, TGFB1, RIPK1, CD137, TET2 and SOCS1. We discuss their genetic mutation, symptoms and current therapeutic methods, and point out the gaps in this field.

Defective regulation of type I interferon response is associated with severe inflammatory phenotypes and autoimmunity. Type I interferonopathies are a clinically heterogenic group of Mendelian diseases with a constitutive activation of this pathway that might present as atypical, severe, early onset rheumatic diseases. Skin vasculopathy with chilblains and livedo reticularis, interstitial lung disease, and panniculitis are common. Recent studies have implicated abnormal responses to nucleic acid stimuli or defective regulation of downstream effector molecules in disease pathogenesis. As observed for IL1-β and autoinflammatory diseases, knowledge of the defects responsible for type I interferonopathies will likely promote the development of targeted therapy.

In the recent past, the gene therapy field has witnessed a remarkable series of successes, many of which have involved primary immunodeficiency diseases, such as X-linked severe combined immunodeficiency, adenosine deaminase deficiency, chronic granulomatous disease, and Wiskott-Aldrich syndrome. While such progress has widened the choice of therapeutic options in some specific cases of primary immunodeficiency, much remains to be done to extend the geographical availability of such an advanced approach and to increase the number of diseases that can be targeted. At the same time, emerging technologies are stimulating intensive investigations that may lead to the application of precise genetic editing as the next form of gene therapy for these and other human genetic diseases.

Cytokines play a major role in lymphoid development. Defects of the common gamma chain (gamma(c)) or of the JAK3 protein in humans have been shown to result in a severe combined immune deficiency (SCID), with a profound defect in T and natural killer (NK)-cell development, whereas B-cell generation is apparently unaffected (T-B+NK-SCID). While extensive molecular and biochemical analysis of these patients has been instrumental in understanding better the biological properties of the gamma(c) and JAK3 protein, an unexpected phenotypic heterogeneity of gamma(c) and JAK3 deficiency has emerged, indicating the need for appropriate and extensive investigations even in patients with atypical presentations. At the same time, characterization of the defects has been instrumental in the development of novel therapeutic approaches, from in utero hematopoietic stem cell transplantation to gene therapy.