Contribution of Impaired DNASE1L3 Activity to Anti-DNA Autoantibody Production in Systemic Lupus Erythematosus

De novo variants in immune regulatory genes in Down syndrome regression disorder

BACKGROUND

Down Syndrome Regression Disorder (DSRD) is a rare and poorly understood disorder of the central nervous system, characterized by acute or subacute neuropsychiatric symptoms in previously healthy individuals with Down syndrome (DS). Many patients exhibit immunotherapy-responsiveness, indicative of immune dysregulation as a potential underlying etiology. While hypotheses are emerging regarding the role of interferon signaling in DSRD and other autoimmune conditions associated with DS, it is unclear why a small subset of individuals with DS develop DSRD. The aim of this study was to investigate genes of immune regulation in persons with DSRD.

METHODS

This study included individuals with DSRD aged 10-30 years with trio exome sequencing performed during the diagnostic work up. Descriptive statistics and univariate analysis (Chi-square and Fisher's exact test) were used to describe and compare the characteristics of individuals with and without variants.

RESULTS

Forty-one individuals with DSRD had trio exome sequencing results. Eight (20%) had heterozygous de novo variants of immune regulatory genes, with four variants being pathogenic or likely pathogenic (UNC13D, XIAP, RNASEH2A, and DNASE1L3). All genes harboring pathogenic variants were associated with interferon type-1 inflammatory response. Individuals harboring variants were more likely to have a preceding trigger (p = 0.03, 95% CI 1.21-97.06), rapid clinical decline in less than 1 month (p = 0.01, 95% CI 1.67-52.06), and MRI abnormalities (p < 0.001, 95% CI 4.89-527.71).

DISCUSSION

A distinct subset of individuals with DSRD exhibited pathogenic variants in immune regulation genes associated with interferon-mediated inflammatory response, coinciding with previously established links between these genes and interferonopathies such as Aicardi-Goutieres syndrome. Our observations suggest that these variants might potentially contribute to the development of DSRD in individuals with DS.

Effect of SARS-CoV-2 Infection and COVID-19 Vaccination on Oxidative Status of Human Placenta: A Preliminary Study

Infection with SARS-CoV-2 during pregnancy increases the risk of pregnancy complications associated with inflammation, which could lead to oxidative stress in the placenta. Whether vaccination against COVID-19 has any effect is unclear. This study aimed to analyze the effects of SARS-CoV-2 infection and vaccination against COVID-19 during pregnancy on oxidative stress in the placenta and on extracellular DNA (ecDNA) in umbilical cord plasma. Placenta samples from healthy uninfected and unvaccinated control patients who recovered from COVID-19 and women vaccinated against COVID-19 during pregnancy were collected. Biomarkers of oxidative damage and antioxidant capacity were assessed in the placenta homogenates. EcDNA and deoxyribonuclease activity were quantified in umbilical cord plasma using real-time PCR and the single radial enzyme diffusion method, respectively. Markers of oxidative damage to lipids and proteins as well as antioxidant capacity in the placenta did not differ between the study groups. No differences were observed in total, nuclear or mitochondrial ecDNA, or deoxyribonuclease activity in the umbilical cord plasma. Taking into account the limits of a small observational study, our results suggest that the infection with SARS-CoV-2 and vaccination against COVID-19 do not induce any major disturbances in the balance between the production of free radicals and antioxidant activity in the placenta. This is in line with the minor effects on fetal outcomes and ecDNA as a suggested marker of fetal well-being.

Systemic Lupus Erythematosus Patients with DNASE1L3·Deficiency Have a Distinctive and Specific Genic Circular DNA Profile in Plasma

Cell-free (cf) extrachromosomal circular DNA (eccDNA) has a potential clinical application as a biomarker. Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with a complex immunological pathogenesis, associated with autoantibody synthesis. A previous study found that SLE patients with deoxyribonuclease 1-like 3 (DNASE1L3) deficiency exhibit changes in the frequency of short and long eccDNA in plasma compared to controls. Here, using the DifCir method for differential analysis of short-read sequenced purified eccDNA data based on the split-read signal of the eccDNA on circulomics data, we show that SLE patients with DNASE1L3 deficiency have a distinctive profile of eccDNA excised by gene regions compared to controls. Moreover, this profile is specific; cf-eccDNA from the top 93 genes is detected in all SLE with DNASE1L3 deficiency samples, and none in the control plasma. The top protein coding gene producing eccDNA-carrying gene fragments is the transcription factor BARX2, which is involved in skeletal muscle morphogenesis and connective tissue development. The top gene ontology terms are ‘positive regulation of torc1 signaling’ and ‘chondrocyte development’. The top Harmonizome terms are ‘lymphopenia’, ‘metabolic syndrome x’, ‘asthma’, ‘cardiovascular system disease‘, ‘leukemia’, and ‘immune system disease’. Here, we show that gene associations of cf-eccDNA can serve as a biomarker in the autoimmune rheumatic diseases.