NF-κB p65 iso5 Δ6/7 and p65 iso5 Δ10 isoforms drive immune-inflammatory remodeling in Fabry disease and GLA variants of uncertain significance

Introduction: Fabry disease (FD) is an X-linked lysosomal storage disorder in which chronic inflammation contributes to disease progression beyond substrate accumulation. Although nuclear factor kappa B (NF-kB) signaling has been implicated in FD pathogenesis, the contribution of alternative NF-kB splicing to immune-inflammatory remodeling remains unknown. Here, we investigated the recently identified NF-kB p65 iso5 splice variants p65 iso5 D6/7 and p65 iso5 D10 in FD and in individuals carrying GLA variants of uncertain significance (GVUS). Methods: We characterized p65 iso5 D6/7 and p65 iso5 D10 in peripheral blood mononuclear cells from 103 patients with FD, including classic and late-onset phenotypes, 30 GVUS subjects, and 30 healthy controls. Isoform expression was assessed at the mRNA and protein levels, and circulating inflammatory mediators were evaluated in selected groups. Results: Both isoforms were constitutively expressed under physiological conditions and were significantly upregulated at the mRNA level in FD, whereas p65 iso5 D6/7 was also increased at the protein level. A similar expression profile was observed in GVUS subjects despite preserved a-galactosidase A activity and normal Lyso-Gb3 levels. In carriers of the p.Ala143Thr (A143T) variant, increased isoform expression was associated with enhanced expression of pro inflammatory cytokines and elevated circulating inflammatory mediators. Discussion: Together with the previously reported downregulation of p65 iso5, these findings indicate that selective NF-kB splice variant redistribution, rather than uniform pathway activation, characterizes immune-inflammatory remodeling in FD. Altered p65 isoforms expression may contribute to immune dysregulation and clinical heterogeneity in FD and GLA variants of uncertain significance.