While IL-2 targets anti-tumor cytotoxic lymphocytes (CTLs) for the treatment of patients with melanoma or renal cell carcinoma, IL-2 directed at regulatory T (Treg) cells could have potential therapeutic value in several immune-related diseases including chronic graft-versus-host disease (cGVHD), type 1 diabetes (T1D) and systemic lupus erythematosus (SLE).
Our findings demonstrate that pretreatment with Treg inducing JES6/IL-2 complexes render BDF1 mice largely resistant to induction of cGvHD, whereas pretreatment with CD8<sup>+</sup> T cell/NK cell inducing S4B6/IL-2 complexes results in a more severe cGvHD.
Substantial preclinical and clinical research into chronic graft-versus-host disease (cGVHD) has come to fruition in the last five years, generating a clear understanding of a complex cytokine-driven cellular network. cGVHD is mediated by naive T cells differentiating within IL-17-secreting T cell and follicular Th cell paradigms to generate IL-21 and IL-17A, which drive pathogenic germinal center (GC) B cell reactions and monocyte-macrophage differentiation, respectively. cGVHD pathogenesis includes thymic damage, impaired antigen presentation, and a failure in IL-2-dependent Treg homeostasis.
We also examined circulating Tregs from patients with cGVHD who were receiving low-dose IL-2 and found that IL-2-induced Treg proliferation was promptly followed by increased PD-1 expression on central-memory Tregs.
Analysis of a subgroup of higher HLA matching showed consistent associations of the recipient IL2-330 GT genotype with risk of chronic GVHD, and the donor CTLA4-CT60 GG genotype with protection from acute GVHD.
Receiver-operating characteristic curve analysis revealed that IFN-γ expression was correlated with the absence of early cGVHD (area under the curve [AUC] = 0.77) and that IL-4 (AUC = 0.89) and IL-2 (AUC = 0.84) expression was correlated with the absence of late cGVHD.
These findings indicate that the cytokine productive capacity of T cell (IFN-gamma and IL-2 could be produced by type 1 T helper (Th1) cells and IL-5 could be produced by type 2 T helper (Th2) cells) was suppressed in patients who had extensive chronic GVHD, while that capacity was almost normal in patients without chronic GVHD and with limited chronic GVHD.
In addition, reduced Forkhead box P3 (Foxp3)+ cells were found in both the peripheral blood (P < 0.001) and conjunctiva (P = 0.042) of cGVHD mice compared with the controls.
Similarly, significantly more relative and absolute regulatory T cell numbers (CD4+FOXP3+) were detected in pts with de novo onset of cGVHD (3.08% and 24.63/μl) compared to those in pts without (1.25% and 9.06/μl) or with quiescent onset of cGVHD (1.15% and 6.91/μl).
Reduction of Foxp3+ T cell subsets involved in incidence of chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.
Absolute counts and % of CD4+ T cells and Treg cells (CD4 + CD25 + FOXP3 + CD127dim/-) were evaluated using flow cytometry in 32 patients with cGvHD treated by ECP for a minimum of 3 months, and up to 12 months.
CD3 mAb treatment ameliorated the severity of the cGVHD-induced lupus nephritis in mice by up-regulation of Foxp3+ regulatory T cells in the target tissue: kidney.
Gene expression of Treg transcription factor FOXP3 was reduced in cGVHD patients compared with patients without cGVHD (P = .009) or healthy donors (P = .01).
In this study group, results documented that local expansion of IL-17-producing cells in the digestive tract correlate with moderate and severe clinical symptoms of cGvHD, in contrast to the skin, where IL-17<sup>+</sup> cells are rather scarcely present (p = 0.0301) and the course of cGvHD is slowly progressing with final organ deterioration.
Of note, MSCs-exo exhibited potent immunomodulatory effects via the inhibition of IL-17-expressing pathogenic T cells and induction of IL-10-expressing regulatory cells during cGVHD.
Overall, our results provide new mechanistic insights that activation of C5a-C5aR signaling was required for IL-17A-induced immune responses in cGVHD and define novel molecular targets for developing effective therapeutics for cGVHD.
Substantial preclinical and clinical research into chronic graft-versus-host disease (cGVHD) has come to fruition in the last five years, generating a clear understanding of a complex cytokine-driven cellular network. cGVHD is mediated by naive T cells differentiating within IL-17-secreting T cell and follicular Th cell paradigms to generate IL-21 and IL-17A, which drive pathogenic germinal center (GC) B cell reactions and monocyte-macrophage differentiation, respectively. cGVHD pathogenesis includes thymic damage, impaired antigen presentation, and a failure in IL-2-dependent Treg homeostasis.