Oral Presentation Melbourne Immunotherapy Spring Symposium 2025

A Novel Targeted Regulatory T Cell Therapy for HLA-DR3-associated Systemic Lupus Erythematosus (127501)

Jessica Whui Yuin Wu 1 , Yi Tian Ting 1 , Elean Tay 1 , Sherman Lim 1 , Rachel Cheong 2 , Janet Chang 1 , Peter Eggenhuizen 1 , Kylie Loh 1 , Hanim Halim 1 , Rangi Kandane-Rathnayake 1 , Alberta Hoi 1 3 , Eric Morand 1 3 , Gwo Yaw Ho 1 , Joshua Ooi 1
  1. Centre for Inflammatory Diseases, Department of Medicine, School of Clinical Sciences, Monash University, Clayton, Victoria, Australia
  2. Division of Medicine, Paediatrics Academic Clinical Programme, KK Women's and Children's Hospital, Singapore
  3. Department of Rheumatology, Monash Health, Clayton, Victoria, Australia

Systemic lupus erythematosus (SLE) is an autoimmune disease with no known cure. T-cells play a central role in SLE pathogenesis, where aberrant T regulatory (Treg) cell function and decreased Treg numbers are strongly implicated. HLA-DR3 is a known dominant SLE risk allele,1 and anti-Smith (Sm) seropositivity is associated with more severe lupus nephritis.2 Data from the Australian Lupus Registry and Biobank (ALRB) shows a strong link between Sm autoreactivity and HLA-DR3, with 30% of anti-Sm+ SLE patients being HLA-DR3+.3

Here we describe the development of a Sm-specific Treg therapy for HLA-DR3-associated, anti-Sm+ SLE.

Two immunogenic DR3-restricted Sm-derived peptides (SmD178-92 and SmB/B’7-21) were identified. To investigate the structural basis of antigen presentation, we successfully expressed and purified soluble recombinant HLA-DR3 in complex with both Sm peptides using the Expi293 expression system. Protein crystallography confirmed stable peptide presentation and revealed key peptide residues involved in immune recognition by autoreactive TCRs.

To explore T-cell response to these epitopes, single-cell RNASeq (10X Genomics) was performed on healthy donor DR3+CD4+ T-cells, which proliferated after being pulsed with the Sm peptides. Single gene expression and pair TCR V(D)J profiling on the proliferated T-cells revealed a dominant TCR clonotype (SmTCR) specific to both Sm peptides and is notably of Treg origin (FoxP3hi).

To assess functionality, SmTCR-Tregs were engineered by lentiviral transduction of healthy donor DR3+CD4+ Tregs. The suppressive function of SmTCR-Tregs was evaluated using an in vitro co-culture with Sm peptide-activated CD4+ T conventional cells. Preliminary results demonstrated that engineered SmTCR-Tregs exhibited up to a 3-fold increase in suppressive capacity compared to non-engineered polyclonal Tregs.

Moving forward, with support from ALRB, we intend to engineer the lead SmTCR into Tregs derived from HLA-DR3+ anti-Sm+ SLE patients to assess their suppressive function in vitro and subsequently in vivo using an already-established humanised SLE mouse model.

  1. Niu, Z., Zhang, P. and Tong, Y. (2015), Value of HLA-DR genotype in systemic lupus erythematosus and lupus nephritis: a meta-analysis. Int J Rheum Dis, 18: 17-28. doi:10.1111/1756-185X.12528
  2. Saleem A, Zeeshan B, Dissanayake G, et al. (2024) Anti-Smith Antibodies as a Predictive Factor for Developing Lupus Nephritis in Systemic Lupus Erythematosus Patients: A Systematic Review. Cureus 16(8): e66270. doi:10.7759/cureus.66270
  3. Unpublished data.