Abstract
Introduction:
Focal segmental glomerulosclerosis (FSGS) is associated with podocyte damage resulting in cytoskeletal alterations leading to foot process effacement. Vincristine is a chemoprotective drug which alters cytoskeletal microtubules and has been used clinically to reverse FSGS. However, the mechanisms underlying the beneficial effect of vincristine are not understood.
Methods:
Immortalized human podocytes were exposed to serum obtained from an adult index patient with FSGS before, during, and after vincristine treatment. We examined the podocyte transcriptome by RNA-sequencing alongside cytoskeletal structure and filtration barrier integrity using a glomerulus-on-a-chip (GOAC) model.
Results:
Podocytes exposed to serum from the index patient with FSGS during or after vincristine treatment contained lower levels of genes associated with microtubule function compared with cells stimulated with serum collected during disease presentation. Presentation serum altered tubulin and F-actin patterning, changes prevented when podocytes were exposed to sera taken during or after vincristine treatment and when vincristine was added to presentation serum. IgG depletion experiments revealed that podocyte damage initiated by the index patient presentation serum was not due to circulating autoantibodies. Addition of serum from 3 more patients with FSGS also caused podocyte tubulin disorganization which was prevented by vincristine. Addition of FSGS serum to the GOAC led to increased albumin permeability in 2 patients, which could be prevented by vincristine.
Conclusion:
Vincristine protects against pathological changes induced by FSGS serum, with preservation of tubulin and F-actin organization in podocytes. Understanding whether vincristine exerts similar effects in other patients with FSGS warrants further investigation to advance our knowledge of this alternative therapeutic.