Lymphocyte Activation Dynamics Is Shaped by Hereditary Components at Chromosome Region 17q12-q21

Genetic analyses point to alterations in immune-related pathways underpinning the association between psychiatric disorders and COVID-19

Current literature suggests that people with psychiatric disorders have a higher risk of COVID-19 infection and a worse prognosis of the disease. We aimed to study the genetic contribution to these associations across seven psychiatric disorders as well as a general psychopathology factor (P-factor) and determine whether these are unique or shared across psychiatric disorders using statistical genetic techniques. Using the largest available genome-wide association studies (GWAS), we found a significant genetic overlap between depression, ADHD, PTSD, and the P-factor with both COVID-19 infection and hospitalization, and between anxiety and COVID-19 hospitalization. We used pairwise GWAS to examine this overlap on a fine-grained scale and identified specific regions of the genome shared between several psychiatric disorders, the P-factor, and COVID-19. Gene-based analysis in these genomic regions suggested possible links with immune-related pathways such as thyroid homeostasis, inflammation, and stress response. Finally, we show preliminary evidence for causal associations between depression, ADHD, PTSD, and the P-factor, and higher COVID-19 infection and hospitalization using Mendelian Randomization and Latent Causal Variable methods. Our results support the hypothesis that the relationship between psychiatric disorders and COVID-19 risk is likely due to shared alterations in immune-related pathways and is not a result of environmental factors alone, shedding light on potentially viable therapeutic targets.

Ceramide Imbalance and Impaired TLR4-Mediated Autophagy in BMDM of an ORMDL3-Overexpressing Mouse Model

Increased orosomucoid-like 3 (ORMDL3) expression levels, due to single nucleotide polymorphisms (SNPs), have been associated with several inflammatory diseases, including asthma and inflammatory bowel diseases. ORMDL proteins inhibit serine palmitoyltransferase (SPT), the first rate-limiting enzyme in de novo sphingolipid synthesis and alter cellular calcium homeostasis. Both processes are essential for immune response. The present study addresses ORMDL3 protein involvement in macrophage physiology using an overexpressing knock-in mouse model. Ceramide content was notably different in the bone-marrow-derived macrophages (BMDM) from the transgenic mouse model compared with the wild type (WT) macrophages. Our data revealed an alteration of de novo production of sphinganine upon BMDM activation in the transgenic mouse. Gene-expression analysis showed that alteration in ORMDL3 expression levels did not affect activation or macrophage polarization. Nevertheless, we studied phagocytosis and autophagy—crucial processes that are dependent on lipid membrane composition. Phagocytosis in transgenic macrophages was not affected by ORMDL3 overexpression, but we did find a reduction in toll-like receptor 4 (TLR-4)-mediated autophagy. Both genetic and functional studies have pointed to autophagy as an essential pathway involved in inflammation. We believe that our work provides new insights into the functional link between ORMDL3 expression and inflammatory diseases.

Risk Factors for Indeterminate Outcome on Interferon Gamma Release Assay in Non-US-Born Persons Screened for Latent Tuberculosis Infection

Background

Non-US-born individuals account for the majority of active tuberculosis (TB) in the United States. Interferon gamma release assay (IGRA) is the preferred diagnostic test for latent TB but can produce an indeterminate result. We investigated the prevalence and predictors of an indeterminate IGRA (IND-IGRA) in a diverse cohort of non-US-born individuals and evaluated outcomes after IND-IGRA.

Methods

We identified patient age ≥18 years who had an outpatient IGRA between 2010 and 2017 in our health system and whose primary language was not English. We used univariate and multivariable logistic regression to examine the association of IND-IGRA with a variety of clinical factors.

Results

Of 3128 outpatients with ≥1 IGRA done, 33% were Asian, 30% Hispanic, and 29% black; 44% were men, and the median age was 50 years. An initial IND-IGRA occurred in 118 (3.8%; 95% confidence interval [CI], 3.1%–4.5%); notably, Asian race (55%) and rheumatologic conditions (25%) were prevalent in this group. In multivariable analysis, Asian race was independently associated with IND-IGRA (adjusted odds ratio [aOR], 2.9; 95% CI, 1.9–4.3), in addition to the presence of anemia and hypoalbuminemia (aOR for interaction, 4.3; 95% CI, 1.3–14.3). Only 55% of patients with an initial IND-IGRA underwent repeat testing; of those who did, 66% had a determinate result.

Conclusions

Asian race and anemia/hypoalbuminemia were independent risk factors for an indeterminate IGRA outcome in foreign-born patients screened in the United States. Our study underscores the importance of following through on indeterminate results in these key subgroups.

Loss of the zona pellucida-binding protein 2 (Zpbp2) gene in mice impacts airway hypersensitivity and lung lipid metabolism in a sex-dependent fashion

The human chromosomal region 17q12-q21 is one of the best replicated genome-wide association study loci for childhood asthma. The associated SNPs span a large genomic interval that includes several protein-coding genes. Here, we tested the hypothesis that the zona pellucida-binding protein 2 (ZPBP2) gene residing in this region contributes to asthma pathogenesis using a mouse model. We tested the lung phenotypes of knock-out (KO) mice that carry a deletion of the Zpbp2 gene. The deletion attenuated airway hypersensitivity (AHR) in female, but not male, mice in the absence of allergic sensitization. Analysis of the lipid profiles of their lungs showed that female, but not male, KO mice had significantly lower levels of sphingosine-1-phosphate (S1P), very long-chain ceramides (VLCCs), and higher levels of long-chain ceramides compared to wild-type controls. Furthermore, in females, lung resistance following methacholine challenge correlated with lung S1P levels (Pearson correlation coefficient 0.57) suggesting a link between reduced AHR in KO females, Zpbp2 deletion, and S1P level regulation. In livers, spleens and blood plasma, however, VLCC, S1P, and sphingosine levels were reduced in both KO females and males. We also find that the Zpbp2 deletion was associated with gain of methylation in the adjacent DNA regions. Thus, we demonstrate that the mouse ortholog of ZPBP2 has a role in controlling AHR in female mice. Our data also suggest that Zpbp2 may act through regulation of ceramide metabolism. These findings highlight the importance of phospholipid metabolism for sexual dimorphism in AHR.