Maurice Stanley1,2, Dr VICKI ATHANASOPOULOS1,2, Ms SOMASUNDHARI SHANMUGANANDAM1,2, Dr TOM LEA-HENRY1,2, Ms AYLA MAY LORENZO1,2, Ms JEAN CAPPELLO1,2, Ms AMELIA COOK1, Dr CAROLA G. VINUESA1,2,4,5, Dr GILES D. WALTERS3, Dr SIMON JIANG1,2,3,4
1John Curtin School of Medical Research, Australian National University, Acton, Canberra, Australia, 2Centre for Personalised Immunology, NHMRC Centre for Research Excellence, Acton, Canberra, Australia, 3Department of Renal Medicine, The Canberra Hospital, Canberra, Australia, 4China Australia Centre for Personalised Immunology, Shanghai Renji Hospital, Jiao Tong University Shanghai, Huangpu Qu, Shanghai, Australia, 5The Francis Crick Institute, London, United Kingdom
Aim:
To use personalised medicine to elucidate and treat the mechanisms driving treatment-resistant complex autoimmunity and chronic kidney disease (CKD).
Background:
A 72-year-old male with treatment-resistant relapsing inflammatory arthritis and pneumonitis, marked hypophosphataemia with massive phosphate requirements, and CKD underwent personalised medicine. He required recurrent hospitalisation for arthritis despite treatment with methotrexate, hydroxyurea, mepolizumab, and secukinumab. Additionally, daily phosphate infusions and oral supplementation were warranted due to renal phosphate wasting associated with progressive CKD.
Methods:
PBMCs and serum were periodically cryopreserved and subject to flow cytometry (FACS)-based immunophenotyping, cytokine analysis and single-cell RNA sequencing. The patient underwent whole exome sequencing (WES) and a candidate pathogenic variant was identified. This variant was then tested using in-vitro assays and replicated by CRISPR-Cas9 in C57BL/6 mice.
Results:
Immunophenotyping of the patient’s PBMCs showed marked expansion of activated CD4+ and CD8+ T cells with Tregs. Serum cytokines demonstrated elevated IL-6 and FGF23. A novel variant in exon 1 of ITK was identified. A 236bp deletion in Itk (Itk-Δex1) and the Itk variant were generated in mice. Itk-Δex1 mice demonstrated a similar cellular phenotype to the proband with marked CD4+ and CD8+ activation. Given molecular and cellular evidence of enhanced NFAT activity, Itk-Δex1 mice and the proband were treated with NFAT-inhibitor tacrolimus. The proband achieved remission and normalisation of hypophosphataemia. Impact of tacrolimus was assessed by pre- and post-treatment FACS and single-cell RNA sequencing.
Conclusion:
This study demonstrates a novel role for ITK in driving autoimmunity and phosphate metabolism. By understanding the genetic and molecular basis of disease, through generation of bespoke mouse models, we demonstrate the efficacy of personalised medicine in understanding and treating otherwise refractory autoimmune disease.
Biography:
I am from Bangalore, India and arrived in Australia in 2017 to pursue my PhD studies at The John Curtin School of Medical Research (JCSMR) under the supervision and guidance of Dr. Simon Jiang and Prof. Carola Vinuesa. My PhD projects focused on understanding the the role of human IRF7 genetic variants in health and disease. At present, I am working as a Postdoctoral fellow at JCSMR, ANU in the Personalised Medicine and Autoimmunity lab headed by Dr. Simon Jiang. My research areas encompass the fields of human genetics, immunology and translational science.