Regulatory T cell enhancement in adults with cystic fibrosis receiving Elexacaftor/Tezacaftor/Ivacaftor therapy

Abstract

Introduction: Cystic fibrosis (CF), especially CF lung disease, is characterized by chronic infection, immune dysfunction including impairment of regulatory T cells (Tregs) and an exaggerated inflammatory response. CF transmembrane conductance regulator (CFTR) modulators have shown to improve clinical outcomes in people with CF (PwCF) with a wide range of CFTR mutations. However, it remains unclear whether CFTR modulator therapy also affects CF-associated inflammation. We aimed to examine the effect of elexacaftor/tezacaftor/ivacaftor therapy on lymphocyte subsets and systemic cytokines in PwCF.

Methods: Peripheral blood mononuclear cells and plasma were collected before and at three and six months after the initiation of elexacaftor/tezacaftor/ivacaftor therapy; lymphocyte subsets and systemic cytokines were determined using flow cytometry.

Results: Elexacaftor/tezacaftor/ivacaftor treatment was initiated in 77 PwCF and improved percent predicted FEV1 by 12.5 points (p<0.001) at 3 months. During elexacaftor/tezacaftor/ivacaftor therapy, percentages of Tregs were enhanced (+18.7%, p<0.001), with an increased proportion of Tregs expressing CD39 as a marker of stability (+14.4%, p<0.001). Treg enhancement was more pronounced in PwCF clearing Pseudomonas aeruginosa infection. Only minor, non-significant shifts were observed among Th1-, Th2- and Th17-expressing effector T helper cells. These results were stable at 3- and 6-month follow-up. Cytokine measurements showed a significant decrease in interleukin-6 levels during treatment with elexacaftor/tezacaftor/ivacaftor (-50.2%, p<0.001).

Conclusion: Treatment with elexacaftor/tezacaftor/ivacaftor was associated with an increased percentage of Tregs, especially in PwCF clearing Pseudomonas aeruginosa infection. Targeting Treg homeostasis is a therapeutic option for PwCF with persistent Treg impairment.

Keywords: CFTR modulator therapy; Pseudomonas aeruginosa; cystic fibrosis - immunology; cytokines; immunophenotyping; pulmonary infection.

Figure 1

Changes of lymphocyte subsets during treatment with elexacaftor/tezacaftor/ivacaftor. (A) Data shown are the proportion of Tregs (CD4⁺, CD25⁺, CD127^- as a proportion of T helper cells) at T0, T1 and T2, and Tregs with CD39⁺ expression (as a proportion of total Tregs) as a marker of stability in pro-inflammatory environments. Tregs (+18.7%) and CD39⁺ Tregs (+14.4%) significantly increased between T0 and T1, and between T0 and T2, then remained stable between T1 and T2. (B): CD4⁺ T helper (as a percentage of T cells), effector helper T cells (T_h; as a percentage of total T_h) and CD8⁺ T cells (as a percentage of T cells) before, and after 3 months (T1) and 6 months (T2) of treatment with elexacaftor/tezacaftor/ivacaftor in PwCF. Percentages of effector T_h cells significantly decreased after initiation of elexacaftor/tezacaftor/ivacaftor therapy and remained lower at T2. Percentages of CD4⁺ and CD8⁺ T cells were stable between T0 and T2. Statistics: Values are median, Wilcoxon signed rank test. ns, not statistically significant. *p < 0.05; ***p < 0.001.

Figure 2

Radar plot of percentage change in lymphocyte subsets at T1 (3 months after initiation of elexacaftor/tezacaftor/ivacaftor, red) and T2 (6 months after initiation of elexacaftor/tezacaftor/ivacaftor, blue) compared with baseline (T0).

Figure 3

Effect of Pseudomonas aeruginosa infection on regulatory T cells (Tregs). Data showed are for CD25⁺ CD127^- Treg (as a proportion of T helper cells), stratified for P. aeruginosa infection. PwCF with chronic P. aeruginosa infection tended to have lower percentages of Tregs (black) compared to PwCF without chronic P. aeruginosa infection (grey) before therapy (T0). Treg impairment in PwCF with P. aeruginosa infection appeared to be rebalanced at T1 and T2. Values are median, and p-values were determined using the Wilcoxon signed rank test. ***p < 0.001.