bims-actimu 2024-07-21 papers

Issue of 2024–07–21
two papers selected by
Elodie Busch, University of Strasbourg

Front Immunol. 2024 ;15 1402139

Hem1 inborn errors of immunity: waving goodbye to coordinated immunity in mice and humans.

Alexandra Christodoulou, Julia Y Tsai, Nutthakarn Suwankitwat, Andreas Anderson, Brian M Iritani.

Inborn errors of immunity (IEI) are a group of diseases in humans that typically present as increased susceptibility to infections, autoimmunity, hyperinflammation, allergy, and in some cases malignancy. Among newly identified genes linked to IEIs include 3 independent reports of 9 individuals from 7 independent kindreds with severe primary immunodeficiency disease (PID) and autoimmunity due to loss-of-function mutations in the NCKAP1L gene encoding Hematopoietic protein 1 (HEM1). HEM1 is a hematopoietic cell specific component of the WASp family verprolin homologous (WAVE) regulatory complex (WRC), which acts downstream of multiple immune receptors to stimulate actin nucleation and polymerization of filamentous actin (F-actin). The polymerization and branching of F-actin is critical for creating force-generating cytoskeletal structures which drive most active cellular processes including migration, adhesion, immune synapse formation, and phagocytosis. Branched actin networks at the cell cortex have also been implicated in acting as a barrier to regulate inappropriate vesicle (e.g. cytokine) secretion and spontaneous antigen receptor crosslinking. Given the importance of the actin cytoskeleton in most or all hematopoietic cells, it is not surprising that HEM1 deficient children present with a complex clinical picture that involves overlapping features of immunodeficiency and autoimmunity. In this review, we will provide an overview of what is known about the molecular and cellular functions of HEM1 and the WRC in immune and other cells. We will describe the common clinicopathological features and immunophenotypes of HEM1 deficiency in humans and provide detailed comparative descriptions of what has been learned about Hem1 disruption using constitutive and immune cell-specific mouse knockout models. Finally, we discuss future perspectives and important areas for investigation regarding HEM1 and the WRC.

Keywords: Hem-1; Hem1; NCKAP1L; actin cytoskeleton; hematopoietic protein-1; immunodeficiency disease; inborn errors of immunity; wave

DOI: https://doi.org/10.3389/fimmu.2024.1402139

Immunol Res. 2024 Jul 17.

A novel MALT1 variant in an Egyptian patient presenting with exfoliative dermatitis: a case-based review.

Rabab El Hawary, Safa Meshaal, Sohilla Lotfy, Dalia Abd Elaziz, Alia S Eldash, Aya Erfan, Radwa Alkady, Rania Darwish, Mai Saad, Engy Chohayeb, Nermeen Galal, Aisha M Elmarsafy.

Inborn errors of the CARD11-BCL10-MALT1 (CBM) signalosome have recently been shown to underlie severe combined immunodeficiency (SCID) and combined immunodeficiency (CID) with variable immunological and clinical phenotypes, and patients usually present with recurrent bacterial, viral, and fungal infections, periodontal disease, enteropathy, dermatitis, and failure to thrive. In the present study, we describe the clinical and immunological characteristics of an Egyptian patient with a mutation in the MALT1 gene. The patient suffered from an itchy exfoliative skin rash and eczematous lesions over his face and flexural surface of the limbs. He also had dental enamel erosion, repeated attacks of diarrhea, and pneumonia. He had elevated serum IgE and normal B- and T-lymphocyte subset counts, but there was an arrest in the B-cell maturation. DOCK8 expression on the lymphocytes by flow cytometry was normal. Next-generation sequencing revealed a novel homozygous variant in the MALT1 gene (c.762dup in exon 5 of 17; p.Ile255TyrfsTer10); this variant is likely pathogenic, thus supporting the genetic diagnosis of immunodeficiency-12 (IMD12). Although the presence of eczema, recurrent sinopulmonary, and staphylococcal infections are suggestive of DOCK8 deficiency, they are also a finding in CARD11 and MALT1 deficiency. Thus, whenever DOCK 8 has been excluded, the molecular diagnosis is mandatory as this could lead to discovering more patients hence better understanding and reporting of the phenotype and natural history of the disease especially since there are very few documented cases. Early diagnosis will also enable the proper patient management by hematopoietic stem cell transplantation (HSCT) prior to the establishment of infections and pulmonary damage leading to a better outcome.

Keywords: Combined immunodeficiency; Eczema; MALT1; next-generation sequencing

DOI: https://doi.org/10.1007/s12026-024-09517-1