Decrease of CD154 intensity on peripheral CD4+ T cells in autoimmune thyroid disease

PD-L1 Inhibits T Cell-Induced Cytokines and Hyaluronan Expression via the CD40-CD40L Pathway in Orbital Fibroblasts From Patients With Thyroid Associated Ophthalmopathy

Thyroid associated ophthalmopathy (TAO), characterized by T cell infiltration and orbital fibroblast activation, is an organ-specific autoimmune disease which is still short of effective and safety therapeutic drugs. The PD-1/PD-L1 pathway has been reported hindering the progression of Graves’ disease to some extent by inhibiting T cell activity, and tumor therapy with a PD-1 inhibitor caused some adverse effects similar to the symptoms of TAO. These findings suggest that the PD-1/PD-L1 pathway may be associated with the pathogenesis of TAO. However, it remains unknown whether the PD-1/PD-L1 pathway is involved in orbital fibroblast activation. Here, we show that orbital fibroblasts from patients with TAO do not express PD-L1. Based on in vitro OF-T cell co-culture system, exogenous PD-L1 weakens T cell-induced orbital fibroblast activation by inhibiting T cell activity, resulting in reduced production of sICAM-1, IL-6, IL-8, and hyaluronan. Additionally, exogenous PD-L1 treatment also inhibits the expression of CD40 and the phosphorylation levels of MAPK and NF-κB pathways in orbital fibroblasts of the OF-T cell co-culture system. Knocking down CD40 with CD40 siRNA or down-regulating the phosphorylation levels of MAPK and NF-κB pathways with SB203580, PD98059, SP600125, and PDTC can both reduce the expression of these cytokines and hyaluronan. Our study demonstrates that the orbital immune tolerance deficiency caused by the lack of PD-L1 in orbital fibroblasts may be one of the causes for the active orbital inflammation in TAO patients, and the utilization of exogenous PD-L1 to reconstruct the orbital immune tolerance microenvironment may be a potential treatment strategy for TAO.

Stimulation-dependent induction of CD154 on a subset of CD4+ FoxP3+ T-regulatory cells

CD40-ligand/CD154 is predominantly expressed on activated CD4 T cells and plays a central role in regulating CD4 T-cell-dependent responses. To define the relative abilities of CD4 T-cell functional subsets in the induction of CD154--specifically FoxP3- effector, versus FoxP3+ regulatory, CD4 T cells--multiple CD4 T cell preparations were isolated from B6 and B6.FoxP3-GFP mice and stimulated in vitro to examine the kinetics of stimulation-dependent CD154 expression. CD154 was induced in 40-60% of total CD4 T cells in various cell preparations. However, despite similar kinetics of CD154-induced expression, the average percentage of CD154 expression among CD4+ FoxP3+ T regulatory (Treg) cells was only about 4-9%. Such differential, stimulation-dependent CD154 induction by total CD4+ T cells versus CD4+ FoxP3+ Treg cells was consistent, despite multiple stimulation conditions utilizing a variety of cell preparations of different composition. Similar induction of CD154 occurred irrespective of whether the CD4+ FoxP3+ Treg cells were first sorted to 98% purity and stimulated in vitro alone, or stimulated as non-purified cells in the presence of CD4+ FoxP3- T effector cells, suggesting that CD154 induction by CD4+ FoxP3+ Treg cells is regulated by cell-intrinsic mechanisms. Differential CD154 induction may be a key factor in determining the distinguishable functions of FoxP3- T-effector, versus FoxP3+ Treg, CD4+ T cells.

Stimulation-dependent induction of CD154 on a subset of CD4+ FoxP3+ T-regulatory cells

CD40-ligand/CD154 is predominantly expressed on activated CD4 T cells and plays a central role in regulating CD4 T-cell-dependent responses. To define the relative abilities of CD4 T-cell functional subsets in the induction of CD154--specifically FoxP3- effector, versus FoxP3+ regulatory, CD4 T cells--multiple CD4 T cell preparations were isolated from B6 and B6.FoxP3-GFP mice and stimulated in vitro to examine the kinetics of stimulation-dependent CD154 expression. CD154 was induced in 40-60% of total CD4 T cells in various cell preparations. However, despite similar kinetics of CD154-induced expression, the average percentage of CD154 expression among CD4+ FoxP3+ T regulatory (Treg) cells was only about 4-9%. Such differential, stimulation-dependent CD154 induction by total CD4+ T cells versus CD4+ FoxP3+ Treg cells was consistent, despite multiple stimulation conditions utilizing a variety of cell preparations of different composition. Similar induction of CD154 occurred irrespective of whether the CD4+ FoxP3+ Treg cells were first sorted to 98% purity and stimulated in vitro alone, or stimulated as non-purified cells in the presence of CD4+ FoxP3- T effector cells, suggesting that CD154 induction by CD4+ FoxP3+ Treg cells is regulated by cell-intrinsic mechanisms. Differential CD154 induction may be a key factor in determining the distinguishable functions of FoxP3- T-effector, versus FoxP3+ Treg, CD4+ T cells.

Label-free proteomics reveals decreased expression of CD18 and AKNA in peripheral CD4+ T cells from patients with Vogt-Koyanagi-Harada syndrome

Vogt-Koyanagi-Harada (VKH) syndrome is a systemic autoimmune disease. CD4⁺ T cells have been shown to be involved in autoimmune diseases including VKH syndrome. To screen aberrantly expressed membrane proteins in CD4⁺ T cell from patients with active VKH syndrome, blood samples were taken from five patients with active VKH syndrome and five healthy individuals. A label-free quantitative proteomic strategy was used to identify the differently expressed proteins between the two groups. The results revealed that the expression of 102 peptides was significantly altered (p<0.05) between two groups and matched amino acid sequences of proteins deposited in the international protein index (ipi.HUMAN.v3.36.fasta). The identified peptides corresponded to 64 proteins, in which 30 showed more than a 1.5-fold difference between the two groups. The decreased expression of CD18 and AKNA transcription factor (AKNA), both being three-fold lower than controls in expression identified by the label-free method, was further confirmed in an additional group of five active VKH patients and six normal individuals using the Western blot technique. A significantly decreased expression of CD18 and AKNA suggests a role for both proteins in the pathogenesis of this syndrome.

Decrease of intrathyroidal CD161+Valpha24+Vbeta11+ NKT cells in Graves' disease

To clarify changes in the intrathyroidal natural killer T (NKT) cell subset, which prevents autoimmunity in patients with Graves' disease (GD), we examined intrathyroidal and peripheral lymphocytes in 11 patients with GD and peripheral lymphocytes in nine healthy volunteers using three-color flow cytometry. The proportion of CD161 (+) T cell receptor Valpha24 (+) Vbeta11 (+) cells, which represent the NKT cell subset, was lower in the thyroid of patients with GD than in the peripheral blood of the same patients and in the peripheral blood of healthy subjects. These results indicate that the proportion of intrathyroidal NKT cells is decreased in patients with GD and that this decrease may contribute to incomplete regulation of autoreactive T cells in GD.

Ratio of serum IgG3 to total IgG concentration and goiter size are independent factors in intractability of Graves' disease

Peripheral immunoglobulin (Ig) G(3)-secreting cells and serum concentrations of interleukin (IL)-10, a class-switching factor to IgG(3)-secreting cells, increase in patients with intractable Graves' disease (GD). However, they are not practical for laboratory tests. To find more stable and easily detectable markers of disease intractability or disease severity in patients with GD or Hashimoto's disease (HD), we examined the serum concentration of IgG(3) in 58 euthyroid GD patients who had been undergoing antithyroid drug treatment for more than 5 years but still must continue drug treatment to maintain a euthyroid state (intractable GD), 26 GD patients who had maintained a euthyroid state for more than 2 years without any treatment (GD in remission), 20 untreated, thyrotoxic GD patients, 40 euthyroid HD patients treated with thyroxine (5 men and 35 women), 13 untreated, euthyroid HD patients, and 39 healthy volunteers. Serum concentrations of IgG(3 )increased in euthyroid patients with intractable GD and in those with GD in remission, but serum concentrations of IgG were not altered. The ratio of serum concentrations of IgG(3) to total IgG (IgG(3)/IgG ratio) was higher in euthyroid patients with intractable GD than in those with GD in remission. Multiple logistic-regression analysis demonstrated that IgG(3)/IgG ratio and goiter size were independent factors in disease intractability of GD patients. These results suggest that IgG(3)/IgG ratio and goiter size may be used as independent markers associated with GD intractability.

Serum CD40/CD40L system in Graves' disease and Hashimoto's thyroiditis related to soluble Fas, FasL and humoral markers of autoimmune response

Activated CD4 T cells' express CD40 ligand (CD154) interacting with CD40 on the B cells surface, protecting them from Fas-mediated apoptosis and in this study, influence humoral response. The aim of the study was to assess soluble CD40 and CD154 in Graves' disease (GD) and Hashimoto's thyroiditis (HT) in relation to Fas and FasL and to the markers of humoral response: aTPO, aTG and aTSHR. The study was carried out in 5 groups of subjects: 1/14 patients with GD in euthyreosis on methimazol (euGD), 2/20 patients with hyperthyroid GD (hrGD), 3/15 patients with HT in euthyreosis on levothyroxine (euHT), 4/16 patients with hypothyroid Ht (hoHT), 5/12 healthy volunteers, age and sex-matched to groups 1-4. The serum levels of CD40, CD154, Fas and FasL, aTPO and aTG were determined by ELISA and aTSHR was determined by the RIA method. CD40 serum concentration was significantly higher in hoHT individuals: 55.8 (24.0-83.2) pg/ml (p<0.01) and euHT patients: 51.2 (20.0-80.1) (p<0.05) as compared to the controls. Also sCD40L values were significantly increased in euHT individuals: 5.1 (1.0-11.8) (p<0.05) and hoHT patients: 3.9 (0.7-11.2) ng/ml (p<0.05) as compared to the controls. There was a positive correlation between sCD40 and sCD154 in the patients studied (r=0.36, p<0.001). In HT patients we found positive correlations between sCD40 and aTPO (r=0.45, p<0.001) and sFas (r=0.36, p<0.05) as well as a negative correlation between sCD40 and FasL (r=-0.24, p<0.05). In GD patients there was a positive correlation between sCD40 and aTSHR (r=0.28, p<0.05). In summary, our results suggest that CD40/CD154 interaction plays an important role in the regulation of autoimmune humoral response, both in Hashimoto's thyroiditis and Graves' disease. Fas-mediated apoptosis seems to be involved in this process especially in Hashimoto thyroiditis. Soluble CD40 may serve as a marker of the active stage of autoimmune thyroid disease.