The role of vascular inflammation markers in deficiency of adenosine deaminase 2

Accumulation of endogenous adenosine improves cardiomyocyte metabolism via epigenetic reprogramming in an ischemia-reperfusion model

Adenosine kinase (ADK) plays the major role in cardiac adenosine metabolism, so that inhibition of ADK increases myocardial adenosine levels. While the cardioprotective actions of extracellular adenosine against ischemia/reperfusion (I/R) are well-established, the role of cellular adenosine in protection against I/R remains unknown. Here we investigated the role of cellular adenosine in epigenetic regulation on cardiomyocyte gene expression, glucose metabolism and tolerance to I/R. Evans blue/TTC staining and echocardiography were used to assess the extent of I/R injury in mice. Glucose metabolism was evaluated by positron emission tomography and computed tomography (PET/CT). Methylated DNA immunoprecipitation (MeDIP) and bisulfite sequencing PCR (BSP) were used to evaluate DNA methylation. Lentiviral/adenovirus transduction was used to overexpress DNMT1, and the OSI-906 was administered to inhibit IGF-1. Cardiomyocyte-specific ADK/IGF-1-knockout mice were used for mechanistic experiments.Cardiomyocyte-specific ADK knockout enhanced glucose metabolism and ameliorated myocardial I/R injury in vivo. Mechanistically, ADK deletion caused cellular adenosine accumulation, decreased DNA methyltransferase 1 (DNMT1) expression and caused hypomethylation of multiple metabolic genes, including insulin growth factor 1 (IGF-1). DNMT1 overexpression abrogated these beneficial effects by enhancing apoptosis and decreasing IGF-1 expression. Inhibition of IGF-1 signaling with OSI-906 or genetic knocking down of IGF-1 also abrogated the cardioprotective effects of ADK knockout, revealing the therapeutic potential of increasing IGF-1 expression in attenuating myocardial I/R injury. In conclusion, the present study demonstrated that cardiomyocyte ADK deletion ameliorates myocardial I/R injury via epigenetic upregulation of IGF-1 expression via the cardiomyocyte adenosine/DNMT1/IGF-1 axis.

A Narrative Review of the Neurological Manifestations of Human Adenosine Deaminase 2 Deficiency

Deficiency of human adenosine deaminase type 2 (DADA2) is a complex systemic autoinflammatory disorder characterized by vasculopathy, immune dysregulation, and hematologic abnormalities. The most notable neurological manifestations of DADA2 are strokes that can manifest with various neurological symptoms and are potentially fatal. However, neurological presentations can be diverse. We here present a review of the neurological manifestations of DADA2 to increase clinical awareness of DADA2 as the underlying diagnosis. We reviewed all published cases of DADA2 from 1 January 2014 until 19 July 2022 found via PubMed. A total of 129 articles describing the clinical features of DADA2 were included in the analysis. Six hundred twenty-eight patients diagnosed with DADA2 were included in the review. 50.3% of patients had at least signs of one reported neurological event, which was the initial or sole manifestation in 5.7% and 0.6%, respectively. 77.5% of patients with neurological manifestations had at least signs of one cerebrovascular accident, with lacunar strokes being the most common and 35.9% of them having multiple stroke episodes. There is a remarkable predilection for the brain stem and deep gray matter, with 37.3% and 41.6% of ischemic strokes, respectively. Other neurological involvement included neuropathies, focal neurological deficits, ophthalmological findings, convulsions, and headaches. In summary, neurological manifestations affect a significant proportion of patients with DADA2, and the phenotype is broad. Neurological manifestations can be the first and single manifestation of DADA2. Therefore, stroke, encephalitis, posterior reversible encephalopathy syndrome, mononeuropathy and polyneuropathy, and Behçet's disease-like presentations should prompt the neurologist to exclude DADA2, especially but not only in childhood.

Comparison of disease phenotypes and mechanistic insight on causal variants in patients with DADA2

BACKGROUND

Deficiency of adenosine deaminase 2 (DADA2) results in heterogeneous manifestations including systemic vasculitis and red cell aplasia. The basis of different disease phenotypes remains incompletely defined.

OBJECTIVE

We sought to further delineate disease phenotypes in DADA2 and define the mechanistic basis of ADA2 variants.

METHODS

We analyzed the clinical features and ADA2 variants in 33 patients with DADA2. We compared the transcriptomic profile of 14 patients by bulk RNA sequencing. ADA2 variants were expressed experimentally to determine impact on protein production, trafficking, release, and enzymatic function.

RESULTS

Transcriptomic analysis of PBMCs from DADA2 patients with the vasculitis phenotype or pure red cell aplasia phenotype exhibited similar upregulation of TNF, type I interferon, and type II interferon signaling pathways compared with healthy controls. These pathways were also activated in 3 asymptomatic individuals with DADA2. Analysis of ADA2 variants, including 7 novel variants, showed different mechanisms of functional disruption including (1) unstable transcript leading to RNA degradation; (2) impairment of ADA2 secretion because of retention in the endoplasmic reticulum; (3) normal expression and secretion of ADA2 that lacks enzymatic function; and (4) disruption of the N-terminal signal peptide leading to cytoplasmic localization of unglycosylated protein.

CONCLUSIONS

Transcriptomic signatures of inflammation are observed in patients with different disease phenotypes, including some asymptomatic individuals. Disease-associated ADA2 variants affect protein function by multiple mechanisms, which may contribute to the clinical heterogeneity of DADA2.

Case Report: Patient with deficiency of ADA2 presenting leukocytoclastic vasculitis and pericarditis during infliximab treatment

Deficiency of adenosine deaminase 2 (DADA2), first reported in 2014, is a disease with great phenotypic variability, which has been increasingly reported. Therapeutic response depends on the phenotype. We present a case of an adolescent with recurrent fever, oral aphthous ulcers, and lymphadenopathy from 8 to 12 years of age and subsequently presented with symptomatic neutropenia. After the diagnosis of DADA2, therapy with infliximab was started, but after the second dose, she developed leukocytoclastic vasculitis and showed symptoms of myopericarditis. Infliximab was switched to etanercept, with no relapses. Despite the safety of tumor necrosis factor alpha inhibitors (TNFi), paradoxical adverse effects have been increasingly reported. The differential diagnosis between disease new-onset manifestations of DADA2 and side effects of TNFi can be challenging and warrants further clarification.