Hemophagocytic lymphohistiocytosis (HLH) is characterized by immune dysregulation due to inadequate restraint of overactivated immune cells and is associated with a variable clinical spectrum having overlap with more common pathophysiologies. HLH is difficult to diagnose and can be part of inflammatory syndromes. Here, we identify a novel hematological/autoinflammatory condition (NOCARH syndrome) in four unrelated patients with superimposable features, including neonatal-onset cytopenia with dyshematopoiesis, autoinflammation, rash, and HLH. Patients shared the same de novo CDC42 mutation (Chr1:22417990C>T, p.R186C) and altered hematopoietic compartment, immune dysregulation, and inflammation. CDC42 mutations had been associated with syndromic neurodevelopmental disorders. In vitro and in vivo assays documented unique effects of p.R186C on CDC42 localization and function, correlating with the distinctiveness of the trait. Emapalumab was critical to the survival of one patient, who underwent successful bone marrow transplantation. Early recognition of the disorder and establishment of treatment followed by bone marrow transplant are important to survival.

Natural killer (NK) cells are innate immune effectors capable of broad cytotoxicity via germline-encoded receptors and can have conferred cytotoxic potential via the addition of chimeric antigen receptors. Combined with their reduced risk of graft-versus-host disease (GvHD) and cytokine release syndrome (CRS), NK cells are an attractive therapeutic platform. While significant progress has been made in treating hematological malignancies, challenges remain in using NK cell-based therapy to combat solid tumors due to their immunosuppressive tumor microenvironments (TMEs). The development of novel strategies enabling NK cells to resist the deleterious effects of the TME is critical to their therapeutic success against solid tumors. In this review, we discuss strategies that apply various genetic and non-genetic engineering approaches to enhance receptor-mediated NK cell cytotoxicity, improve NK cell resistance to TME effects, and enhance persistence in the TME. The successful design and application of these strategies will ultimately lead to more efficacious NK cell therapies to treat patients with solid tumors. This review outlines the mechanisms by which TME components suppress the anti-tumor activity of endogenous and adoptively transferred NK cells while also describing various approaches whose implementation in NK cells may lead to a more robust therapeutic platform against solid tumors.

Currently, curative therapies for heart valve diseases do not exist, thus motivating the need for new therapeutics, regenerative and tissue-engineered valves, and further basic research into pathological mechanisms. For studying valve diseases and developing valve therapies, effective methods to manipulate gene expression in primary valvular interstitial cells (VICs), which promote calcification in disease, would be valuable. Unfortunately, there is little information reported about effective gene delivery methods for VICs. Adeno-associated virus (AAV) is a clinically proven gene delivery vector capable of transducing many cell types and tissues, but has not yet been reported to infect valvular cells. In this study, AAV serotypes 1–9 were tested for their ability to deliver a green fluorescent protein ( GFP ) reporter into VICs in vitro . Flow cytometry results indicate AAV2 and AAV3 are capable of transducing VICs more efficiently than other serotypes. Furthermore, transduction efficiencies can be optimized by increasing the multiplicity of infection (MOI) and using self-complementary, double-stranded genomes, yielding up to 98% successfully transduced cells. Transduction of VICs by AAV2 or AAV3 in the presence of competing soluble heparin significantly reduces delivery efficiencies, suggesting heparan sulfate proteoglycans act as the primary VIC receptors of these two serotypes. Overall, this study establishes AAV2 and AAV3 as efficient gene delivery vehicles for primary VICs. Such effective delivery vectors for valve cells may be broadly useful for numerous applications, including the study of valvular cell biology, development of valve disease therapies, and regulation of genes for tissue engineering heart valves.

Natural killer cell deficiencies (NKDs) are an emerging phenotypic subtype of primary immune deficiency. NK cells provide a defense against virally infected cells using a variety of cytotoxic mechanisms, and patients who have defective NK cell development or function can present with atypical, recurrent, or severe herpesviral infections. The current pipeline for investigating NKDs involves the acquisition and clinical assessment of patients with a suspected NKD followed by subsequent in silico, in vitro, and in vivo laboratory research. Evaluation involves initially quantifying NK cells and measuring NK cell cytotoxicity and expression of certain NK cell receptors involved in NK cell development and function. Subsequent studies using genomic methods to identify the potential causative variant are conducted along with variant impact testing to make genotype-phenotype connections. Identification of novel genes contributing to the NKD phenotype can also be facilitated by applying the expanding knowledge of NK cell biology. In this review, we discuss how NKDs that affect NK cell cytotoxicity can be approached in the clinic and laboratory for the discovery of novel gene variants.

Objective: Deficiency of adenosine deaminase 2 (DADA2) is a monogenic autoinflammatory disease manifested as polyarteritis nodosa, stroke, and bone marrow failure. Leveraging an international cohort of 200 DADA2 cases, we aimed to characterize the diagnostic utility of a plasma ADA2 enzyme activity assay and understand the implications of residual ADA2 activity. Methods: Data were collected from individuals who underwent ADA2 testing from 2018 to 2025. Plasma ADA2 activity was determined using an established spectrophotometric assay. ADA2 variants were analyzed in transfected cells by enzyme assay and western blotting. Results: We determined that plasma ADA2 activity is 99.0% and 96.0% sensitive and 99.7% and 98.8% specific in distinguishing genetically confirmed DADA2 cases from controls and carriers, respectively. Eighteen individuals with DADA2 (9%) possessed detectable ADA2 activity, including several cases with levels seen in carriers. Residual ADA2 activity was associated with the vasculitis/inflammatory phenotype but not with disease severity. Genotype analysis revealed that 14 of 18 cases with residual plasma activity possessed at least one hypomorphic missense variant with greater than 20% residual ADA2 function when overexpressed in 293T cells, often occurring in trans with a more deleterious variant. In vitro analysis revealed that missense ADA2 variants exert variable dominant‐negative effects by forming large intracellular protein aggregates via disulfide bond formation at a cysteine residue (Cys408). Conclusion: We confirmed the utility of plasma ADA2 activity as a diagnostic assay and showed that the inflammatory phenotype of DADA2 occurred in cases with residual activity. In vitro findings illustrate potential interactions of ADA2 variants to synergistically disrupt protein function.