Neurological phenotype of adenosine deaminase 2 deficient patients: a cohort study.

BACKGROUND AND PURPOSE: Patients with adenosine deaminase 2 (ADA2) deficiency can present with various neurological manifestations due to vasculopathies and autoinflammation. These include ischaemic and hemorrhagic stroke, but less clearly defined neurological symptoms have also been reported. METHODS: In this cohort study, patients with confirmed ADA2 deficiency from seven university hospitals in the Netherlands were included. The frequency and recurrence rates of neurological manifestations before and after initiation of tumor necrosis factor α (TNF-α) inhibiting therapy were analyzed. RESULTS: Twenty-nine patients were included with a median age at presentation of 5 years (interquartile range 1-17). Neurological manifestations occurred in 19/29 (66%) patients and were the presenting symptom in 9/29 (31%) patients. Transient ischaemic attack (TIA)/ischaemic stroke occurred in 12/29 (41%) patients and was the presenting symptom in 8/29 (28%) patients. In total, 25 TIAs/ischaemic strokes occurred in 12 patients, one after initiation of TNF-α inhibiting therapy and one whilst switching between TNF-α inhibitors. None was large-vessel occlusion stroke. Two hemorrhagic strokes occurred: one aneurysmatic subarachnoid hemorrhage and one spontaneous intracerebral hemorrhage. Most neurological symptoms, including cranial nerve deficits, vertigo, ataxia and seizures, were caused by TIAs/ischaemic strokes and seldom recurred after initiation of TNF-α inhibiting therapy. CONCLUSIONS: Neurological manifestations, especially TIA/ischaemic stroke, are common in patients with ADA2 deficiency and frequently are the presenting symptom. Because it is a treatable cause of young stroke, for which antiplatelet and anticoagulant therapy are considered contraindicated, awareness amongst neurologists and pediatricians is important. Screening for ADA2 deficiency in young patients with small-vessel ischaemic stroke without an identified cause should be considered.

YajC, a predicted membrane protein, promotes Enterococcus faecium biofilm formation in vitro and in a rat endocarditis model.

Biofilm formation is a critical step in the pathogenesis of difficult-to-treat Gram-positive bacterial infections. We identified that YajC, a conserved membrane protein in bacteria, plays a role in biofilm formation of the clinically relevant Enterococcus faecium strain E1162. Deletion of yajC conferred significantly impaired biofilm formation in vitro and was attenuated in a rat endocarditis model. Mass spectrometry analysis of supernatants of washed ΔyajC cells revealed increased amounts in cytoplasmic and cell-surface-located proteins, including biofilm-associated proteins, suggesting that proteins on the surface of the yajC mutant are only loosely attached. In Streptococcus mutans YajC has been identified in complex with proteins of two cotranslational membrane protein-insertion pathways; the signal recognition particle (SRP)-SecYEG-YajC-YidC1 and the SRP-YajC-YidC2 pathway, but its function is unknown. In S. mutans mutation of yidC1 and yidC2 resulted in impaired protein insertion in the cell membrane and secretion in the supernatant. The E. faecium genome contains all homologous genes encoding for the cotranslational membrane protein-insertion pathways. By combining the studies in S. mutans and E. faecium, we propose that YajC is involved in the stabilization of the SRP-SecYEG-YajC-YidC1 and SRP-YajC-Yid2 pathway or plays a role in retaining proteins for proper docking to the YidC insertases for translocation in and over the membrane.

Pulmonary Computed Tomography Screening Frequency in Primary Antibody Deficiency.

BACKGROUND: Patients with primary antibody deficiency (PAD) frequently suffer from pulmonary complications, associated with severe morbidity and mortality. Hence, regular pulmonary screening by computed tomography (CT) scanning is advised. However, predictive risk factors for pulmonary morbidity are lacking. OBJECTIVE: To identify patients with PAD at risk for pulmonary complications necessitating regular CT screening. METHODS: A retrospective, longitudinal cohort study of patients with PAD (median follow-up 7.4 [2.3-14.8] years) was performed. CTs were scored using the modified Brody-II scoring system. Clinical and laboratory parameters were retrospectively collected. Potential risk factors were identified by univariate analysis when P < .2 and confirmed by multivariable logistic regression when P < .05. RESULTS: The following independent risk factors for progression of airway disease (AD) were identified: (1) diagnosis of X-linked agammaglobulinemia (XLA), (2) recurrent airway infections (2.5/year), and (3) the presence of AD at baseline. Signs of AD progression were detected in 5 of 11 patients with XLA and in 17 of 80 of the other patients with PAD. Of the 22 patients who progressed, 17 had pre-existent AD scores ≥7.0%. Increased AD scores were related to poorer forced expiratory volume in 1 second values and chronic cough. Common variable immunodeficiency and increased CD4 effector/memory cells were risk factors for an interstitial lung disease (ILD) score ≥13.0%. ILD ≥13.0% occurred in 12 of 80 patients. Signs of ILD progression were detected in 8 of 80 patients, and 4 of 8 patients showing progression had pre-existent ILD scores ≥13.0%. CONCLUSION: We identified risk factors that distinguished patients with PAD at risk for AD and ILD presence and progression, which could guide future screening frequency; however, independent and preferably prospective validation is needed.

Association of autoantibodies with the IFN signature and NETosis in patients with systemic lupus erythematosus.

Objective: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a variety of disease symptoms and an unpredictable clinical course. To improve treatment outcome, stratification based on immunological manifestations commonly seen in patients with SLE such as autoantibodies, type I interferon (IFN) signature and neutrophil extracellular trap (NET) release may help. It is assumed that there is an association between these immunological phenomena, since NET release induces IFN production and IFN induces autoantibody formation via B-cell activation. Here we studied the association between autoantibodies, the IFN signature, NET release, and clinical manifestations in patients with SLE. Methods: We performed principal component analysis (PCA) and hierarchical clustering of 57 SLE-related autoantibodies in 25 patients with SLE. We correlated each autoantibody to the IFN signature and NET inducing capacity. Results: We observed two distinct clusters: one cluster contained mostly patients with a high IFN signature. Patients in this cluster often present with cutaneous lupus, and have higher anti-dsDNA concentrations. Another cluster contained a mix of patients with a high and low IFN signature. Patients with high and low NET inducing capacity were equally distributed between the clusters. Variance between the clusters is mainly driven by antibodies against histones, RibP2, RibP0, EphB2, RibP1, PCNA, dsDNA, and nucleosome. In addition, we found a trend towards increased concentrations of autoantibodies against EphB2, RibP1, and RNP70 in patients with an IFN signature. We found a negative correlation of NET inducing capacity with anti-FcER (r = -0.530; p = 0.007) and anti-PmScl100 (r = -0.445; p = 0.03). Conclusion: We identified a subgroup of patients with an IFN signature that express increased concentrations of antibodies against DNA and RNA-binding proteins, which can be useful for further patient stratification and a more targeted therapy. We did not find positive associations between autoantibodies and NET inducing capacity. Our study further strengthens the evidence of a correlation between RNA-binding autoantibodies and the IFN signature.