Morin, L. | bioRxiv Science

bioRxiv2026

Non-HLA antibodies worsen the histological phenotype and prognosis of antibody mediated rejection in kidney allografts

IntroductionAntibody-mediated rejection (AMR) remains a leading cause of kidney allograft failure, with both HLA and non-HLA antibodies implicated in its pathogenesis. The contribution of non-HLA antibodies (non-HLA Abs) to microvascular inflammation (MVI) and graft outcome, particularly in cases lacking donor-specific anti-HLA antibodies (HLA-DSAs), remains incompletely understood. MethodsWe analyzed 571 post-transplant serum samples from 326 patients with histological features of AMR (AMRh) and 164 stable controls. Non-HLA Abs were detected using the previously developed Non-HLA Antibody Detection Immunoassay (NHADIA), and associations were examined with histological lesions, AMRh persistence, and graft outcomes. Biopsies were scored according to Banff 2022 criteria, and patients were stratified by HLA-DSA and NHADIA status. ResultsNHADIA values were significantly higher in AMRh patients compared to controls (P=0.0001), regardless of HLA-DSA status. NHADIA values correlated with the severity of glomerulitis, peritubular capillaritis and global MVI scores. In AMRh patients with HLA-DSAs, non-HLA Abs remained independently associated with MVI severity. Follow-up biopsies revealed persistent AMR lesions in patients with both HLA-DSAs and non-HLA Abs. Allograft survival was lowest in double-positive patients, and NHADIA positivity independently predicted graft loss (HR=2.25, 95% CI: 1.03-4.92, P=0.042). Incorporating NHADIA into the Banff classification reclassified 61% of AMRh cases as "double-positive AMRh," and identified new subgroups with significant prognostic differences. ConclusionPost-transplant detection of non-HLA antibodies identifies a distinct subset of AMR with more severe histology and worse graft prognosis, particularly when coexisting with HLA-DSAs. Integrating non-HLA Ab testing into current diagnostic frameworks may refine AMR classification and improve risk stratification. TRANSLATIONAL STATEMENTThis study highlights the clinical relevance of non-HLA antibodies, identified using our innovative endothelial cell-based assay (NHADIA), in kidney transplant recipients. Their presence is associated with more severe antibody-mediated rejection (AMR) and poorer graft outcomes, even in the absence of donor-specific HLA antibodies. Incorporating non-HLA antibody detection into routine post-transplant evaluation may allow clinicians to better identify high-risk patients, including those previously classified as DSA-negative AMR. This expanded immunological profiling refines AMR diagnosis, improves risk stratification, and opens new avenues for personalized immunosuppressive strategies, ultimately enhancing long-term graft survival and patient care.

pathology↗

bioRxiv2025

Chemical inhibition of SUMOylation activates the FSHD locus

Facioscapulohumeral muscular dystrophy (FSHD) is a progressive and debilitating muscle disease for which no cure currently exists. In the majority of cases, FSHD is associated with the contraction of the D4Z4 macrosatellite repeat array at the 4q35 locus, leading to the inappropriate activation of DUX4, normally expressed during early embryogenesis. In FSHD, the genetic contraction is accompanied by hypomethylation of the D4Z4 array. Although a connection between DNA hypomethylation and DUX4 expression has been suggested, the precise mechanisms that regulate DUX4 transcription remain incompletely defined. The post-translational modification by SUMO was shown previously to repress the expression of Dux, the DUX4 homolog, in mouse embryonic stem cells. Based on these findings, we explored here the contribution of SUMOylation in the regulation of DUX4 in human muscle cells. We demonstrate that TAK981 (subasumstat), a selective SUMOylation inhibitor, promotes transcriptional reprogramming of the 4q35 locus and induces DUX4 expression. Importantly, this activation occurs independently of changes in DNA methylation or SMCHD1 ATPase activity. Our findings identify SUMOylation inhibition as a novel regulatory pathway driving DUX4 expression. This work uncovers the importance of SUMOylation in the epigenetic control of the 4q35 locus and DUX4 transcription, providing a potential therapeutic strategy to modulate DUX4 expression in FSHD.

genetics↗