CADINS in an Adult with Chronic Sinusitis and Atopic Disease

The role of the CBM complex in allergic inflammation and disease

The caspase activation and recruitment domain-coiled-coil (CARD-CC) family of proteins-CARD9, CARD10, CARD11, and CARD14-is collectively expressed across nearly all tissues of the body and is a crucial mediator of immunologic signaling as part of the CARD-B-cell lymphoma/leukemia 10-mucosa-associated lymphoid tissue lymphoma translocation protein 1 (CBM) complex. Dysfunction or dysregulation of CBM proteins has been linked to numerous clinical manifestations known as "CBM-opathies." The CBM-opathy spectrum encompasses diseases ranging from mucocutaneous fungal infections and psoriasis to combined immunodeficiency and lymphoproliferative diseases; however, there is accumulating evidence that the CARD-CC family members also contribute to the pathogenesis and progression of allergic inflammation and allergic diseases. Here, we review the 4 CARD-CC paralogs, as well as B-cell lymphoma/leukemia 10 and mucosa-associated lymphoid tissue lymphoma translocation protein 1, and their individual and collective roles in the pathogenesis and progression of allergic inflammation and 4 major allergic diseases (allergic asthma, atopic dermatitis, food allergy, and allergic rhinitis).

Mechanistic impact of oligomer poisoning by dominant-negative CARD11 variants

The CARD11 scaffold controls antigen receptor signaling to NF-κB, JNK, and mTOR. Three classes of germline mutations in CARD11 cause Primary Immunodeficiency, including homozygous loss-of-function (LOF) mutations in CARD11 deficiency, heterozygous gain-of-function (GOF) mutations in BENTA disease, and heterozygous dominant-negative LOF mutations in CADINS. Here, we characterize LOF CARD11 mutants with a range of dominant-negative activities to identify the mechanistic properties that cause these variants to exert dominant effects when heterozygous. We find that strong dominant negatives can poison signaling from mixed wild-type:mutant oligomers at two steps in the CARD11 signaling cycle, at the Opening Step and at the Cofactor Association Step. Our findings provide evidence that CARD11 oligomer subunits cooperate in at least two steps during antigen receptor signaling and reveal how different LOF mutations in the same oligomeric signaling hub may cause disease with different inheritance patterns.

Skin manifestations of inborn errors of NF-κB

More than 400 single gene defects have been identified as inborn errors of immunity, including many arising from genes encoding proteins that affect NF-κB activity. We summarise the skin phenotypes in this subset of disorders and provide an overview of pathogenic mechanisms. NF-κB acts cell-intrinsically in basal epithelial cells during differentiation of skin appendages, influences keratinocyte proliferation and survival, and both responses to and amplification of inflammation, particularly TNF. Skin phenotypes include ectodermal dysplasia, reduction and hyperproliferation of keratinocytes, and aberrant recruitment of inflammatory cells, which often occur in combination. Phenotypes conferred by these rare monogenic syndromes often resemble those observed with more common defects. This includes oral and perineal ulceration and pustular skin disease as occurs with Behcet's disease, hyperkeratosis with microabscess formation similar to psoriasis, and atopic dermatitis. Thus, these genotype-phenotype relations provide diagnostic clues for this subset of IEIs, and also provide insights into mechanisms of more common forms of skin disease.