Background/Purpose: There is substantial evidence that CD4⁺ effector memory T (T_EM) cells play a crucial role in the pathogenesis of Granulomatosis with polyangiitis (GPA). The activation of CD4⁺ T_EM-cells is uniquely dependent on the voltage-gated potassium Kv1.3 channel. Blocking Kv1.3 channels with the exquisitely specific, highly potent peptide inhibitor dalazatide (formerly ShK-186) has been shown to ameliorate autoimmune disease in animal models of multiple sclerosis and rheumatoid arthritis. Therefore, selective targeting of pathogenic CD4⁺ T_EM-cells is a very promising selective treatment for GPA patients. The aim of this study is to modulate CD4⁺ T_EM-cell activity via Kv1.3 blockade using a specific peptide inhibitor dalazatide in peripheral blood of GPA patients in vitro.

Methods: Peripheral blood of remission GPA patients (R-GPA; n=24) and age- and sex-matched healthy controls (HCs; n=15) was stimulated in vitro with PMA/Ca-Ionomycin in the presence and absence of the Kv1.3 blocker, dalazatide. After stimulation cells were fixed, permeabilized and stained for surface markers (CD3, CD8, CD45RO and CCR7), and intracellular cytokines (IL-4, IL-17, IL-21, IFNγ and TNFα). Relative frequencies of pro-inflammatory cytokine expression were assessed within total CD4⁺ T-cells and CD4⁺ T-cell subsets using flow cytometry. Unstimulated samples were used as a guide to delineate positive and negative populations for the cytokine production.

Results: The percentage of CD4⁺ T_EM cells was significantly increased in R-GPA patients compared to HCs. The intracellular cytokine production in total CD4⁺ T-cells after stimulation was significantly increased in R-GPA patients compared to HCs. Dalazatide suppressed the intracellular cytokine production in total CD4⁺ T-cells of GPA patients, in a dose dependent manner, to levels observed in stimulated total CD4⁺ T-cells of HCs. Similar assays performed in sorted CD4⁺ T-cell subsets revealed that dalazatide predominantly inhibited cytokine production in CD4⁺ T_EM-cells, whereas cytokine production by naïve- and central memory CD4⁺ T-cells was unaffected. production.

Conclusion: The selective Kv1.3 blocker, dalazatide modulates CD4⁺ T-cell activity in GPA patients in vitro. Importantly, dalazatide was able to normalize the pro-inflammatory cytokine production in CD4⁺ T cells from GPA patients. Furthermore, the effect of dalazatide predominantly affects CD4⁺ T_EM-cells by reducing intracellular cytokine production while sparing other CD4⁺ T-cell subsets. These data indicate that dalazatide may hold therapeutic promise in the treatment of GPA by selectively targeting CD4⁺ T_EM-cells. duction by naïve- and central memory CD4⁺ T-cells was unaffected. production.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/dalazatide-modulates-cd4-effector-memory-t-cell-activity-of-patients-with-granulomatosis-with-polyangiitis-in-vitro/