Genetics in systemic lupus erythematosus: entering the borough of cardiovascular risk

Mendelian randomization and pathway analysis demonstrate shared genetic associations between lupus and coronary artery disease

Coronary artery disease (CAD) is a leading cause of death in patients with systemic lupus erythematosus (SLE). Despite clinical evidence supporting an association between SLE and CAD, pleiotropy-adjusted genetic association studies are limited and focus on only a few common risk loci. Here, we identify a net positive causal estimate of SLE-associated non-HLA SNPs on CAD by traditional Mendelian randomization (MR) approaches. Pathway analysis using SNP-to-gene mapping followed by unsupervised clustering based on protein-protein interactions (PPIs) identifies biological networks composed of positive and negative causal sets of genes. In addition, we confirm the casual effects of specific SNP-to-gene modules on CAD using only SNP mapping to each PPI-defined functional gene set as instrumental variables. This PPI-based MR approach elucidates various molecular pathways with causal implications between SLE and CAD and identifies biological pathways likely causative of both pathologies, revealing known and novel therapeutic interventions for managing CAD in SLE.

Association between systemic lupus erythematosus and lung cancer: results from a pool of cohort studies and Mendelian randomization analysis

Background

Epidemiological evidence suggested that systemic lupus erythematosus (SLE) might be correlated with an increased risk of lung cancer. Nevertheless, few studies have comprehensively investigated their correlation and the causal effect remains unclear. With a meta-analysis and Mendelian randomization (MR) approach, we were able to systematically investigate the relationship between SLE and lung cancer risk.

Methods

A systematic search of cohort studies was conducted using network databases from the inception dates to February 1, 2020. Meta-analysis was performed to calculate standardized incidence rate (SIR) and their 95% CI. Furthermore, utilizing 33 SLE-related single nucleotide polymorphisms as instrumental variables (IVs) identified by the latest genome-wide association studies (GWASs), we investigated the correlation between genetically predisposed SLE and lung cancer risk using summary statistics from the International Lung Cancer Consortium (11,348 cases and 15,861 controls). The Inverse variance-weighted method was applied to estimate the causality and we further evaluated the pleiotropy by means of the weighted median and the MR-Egger regression method. Subgroup analysis according to different histotypes of lung cancer was also conducted.

Results

Through meta-analysis of 15 cohort studies involving 110,519 patients, we observed an increased risk of lung cancer among SLE patients (SIR =1.63, 95% CI, 1.39-1.90). Subgroup analysis suggested that female patients (SIR =1.28, 95% CI, 1.13-1.44) have a relatively higher lung cancer risk compared with male patients (SIR =1.15, 95% CI, 1.02-1.30). MR analysis indicated that genetically predisposed SLE was causally associated with an increased lung cancer risk (OR =1.045, 95% CI, 1.005-1.086, P=0.0276). When results were examined by histotypes, a causal relationship was observed between genetically predisposed SLE and squamous cell lung cancer (OR =1.065, 95% CI, 1.002-1.132, P=0.0429). Additionally, the results demonstrated the absence of the horizontal pleiotropy.

Conclusions

Both meta-analysis and MR analysis results suggested that SLE was associated with an increased lung cancer risk. Further investigations are warranted to investigate the etiology underlying the attribution of SLE to lung cancer.