Association of Common Variants of TNFSF13 and TNFRSF13B Genes with CLL Risk and Clinical Picture, as Well as Expression of Their Products—APRIL and TACI Molecules

SIMPLE SUMMARY: A growing body of evidence reported in literature suggests an important role of APRIL in the development and pathogenesis of chronic lymphocytic leukaemia (CLL), in particular elevated levels of soluble APRIL (sAPRIL) and overexpression of its mRNA have been noticed in CLL cells. Moreover, TACI expression has been found to improve the survival ability of CLL cells protecting them from apoptosis in vitro. On the other hand, there are evidence supporting the existence of a genetic predisposition to develop CLL. These data prompted us to investigate the influence of genetic variants of TNFSF13 and TNFRSF13B on the expression level of proteins encoded by these genes and to investigate the association between these variants an CLL risk. ABSTRACT: Interactions between APRIL (TNFSF13) and its receptor TACI (TNFRSF13B) are implicated in providing survival benefits for chronic lymphocytic leukaemia (CLL) cells. Here we explored the relationship between TNFSF13 and TNFRSF13B SNPs and expression of APRIL and TACI molecules and performed extended case-control study to evaluate earlier observations. Expression of APRIL and TACI was detected by FACS for 72 and 145 patients, respectively, and soluble APRIL was measured by ELISA in plasma of 122 patients. Genotypes were determined in 439 CLL patients and 477 control subjects with TaqMan Assays or restriction fragment length polymorphism (RFLP). The rs4968210GG genotype of TNFSF13 was associated with a lower percentage of CD19(+)APRIL(+) cells in CLL patients when compared to (AA + GA) genotypes (p-value = 0.027). Homozygosity at rs11078355 TNFRSF13B was associated with higher CD19(+) TACI(+) cell percentage in CLL patients (p-value = 0.036). The analysis of extended groups of patients and healthy controls confirmed the association of TNFSF13 rs3803800AA genotype with a higher CLL risk (OR = 2.13; CI95% = 1.21; 3.75; p-value = 0.007), while the possession of TNFRSF13B rs4985726G allele (CG + GG) genotype was associated with lower risk of CLL (OR = 0.69; CI95% = 0.51; 0.95; p-value = 0.02). Genetic variants of TNFSF13 and TNFRSF13B may have an impact on APRIL and TACI expression and may be considered as possible CLL risk factors.