Association between genetically proxied PCSK9 inhibition and systemic lupus erythematosus risk: A mendelian randomization study

Abstract Background Preclinical and epidemiological studies suggest that proprotein convertase subtilisin/kexin type 9 (PCSK9) had a potential effect on the development of SLE, but it was unclear whether a causal relationship exists. We aimed to investigate the association between genetically proxied inhibition of PCSK9 and the risk of SLE using a two‐sample Mendelian randomization (MR) approach. Methods Single nucleotide polymorphisms (SNPs) associated with PCSK9 were extracted from pooled data obtained from the Global Lipid Genetics Consortium (GLGC) Genome‐wide Association Study (GWAS) related to LDL‐c levels, which was used as a proxy for PCSK9 inhibition. Pooled statistics for SLE were obtained from an independent GWAS dataset including 5201 SLE patients and 9066 controls. Inverse variance‐weighted random‐effects models were used to examine the association between genetically proxied inhibition of PCSK9 and the risk of SLE. MR‐Egger, weighted median, weighted mode, Simple mode, and co‐location analyses were used as sensitivity analyses to test the robustness of the analyses. Results Genetically proxied inhibition of PCSK9 was associated with a reduced risk of SLE (OR = 0.51, 95% CI = 0.34 to 0.77, p = .001). This finding was replicated in an earlier GLGC GWAS analysis (OR = 0.59, 95% CI = 0.40 to 0.87, p = .007). Sensitivity analysis ensured that the results were robust. Co‐localization analysis did not find evidence of shared causal variation between PCSK9 and SLE. Conclusions This Mendelian randomization study showed that PCSK9 was associated with SLE pathogenesis, and its inhibition was associated with a reduced risk of SLE. This study has offered a prospective therapeutic avenue for intervening in the progression of SLE by inhibiting PCSK9 levels.