CD26/DPP4 levels in peripheral blood and T cells in Hashimoto's thyroiditis with normal thyroid function

Clonal Analysis of Peripheral Blood T Cells in patients with Hashimoto's Thyroiditis at Different Stages using TCR Sequencing

BACKGROUND

Hashimoto's Thyroiditis (HT) is a prevalent autoimmune disorder characterized by progressive thyroid damage mediated by T cells. The clonal diversity and expansion of T cells play a critical role in the pathogenesis of HT, but detailed insights into these characteristics at various disease stages are lacking.

OBJECTIVE

To analyze and compare the clonal diversity and T cell receptor (TCR) repertoire in peripheral blood T cells across different stages of Hashimoto's Thyroiditis using TCR sequencing.

METHODS

Peripheral blood samples from 19 HT patients at different disease stages and 4 healthy controls were collected. TCR sequencing was performed to assess T cell diversity and clonal expansion. Statistical analyses, including Shannon's entropy and Simpson's index, were employed to compare TCR diversity. Additionally, differential VJ gene usage and amino acid sequence diversity were analyzed.

RESULTS

The results revealed significant differences in TCR diversity between HT patients and healthy controls, with HT patients showing lower diversity. Notably, the frequency of hyperexpanded clones was higher in HT patients. Specific VJ genes exhibited differential usage patterns across disease stages, and a set of unique amino acid sequences was identified in each stage.

CONCLUSION

TCR sequencing highlights distinct clonal T cell expansions and shifts in VJ gene usage in HT patients, providing insights into the immune mechanisms driving disease progression.

Increased Thyroid DPP4 Expression Is Associated With Inflammatory Process in Patients With Hashimoto Thyroiditis

CONTEXT

Dipeptidyl peptidase-4 (DPP4) is originally described as a surface protein in lymphocytes. Lymphocyte infiltration and subsequent destruction of thyroid tissue have been considered as the central pathological mechanism in Hashimoto thyroiditis (HT).

OBJECTIVE

The present study aimed to investigate DPP4 expression in peripheral blood and thyroid tissue in HT patients, and explore the role of DPP4 in the pathophysiological process of HT.

METHODS

This case-control study recruited 40 drug-naive HT patients and 81 control individuals. Peripheral blood and thyroid specimens were collected for assessing the expression and activity of DPP4. Moreover, single-cell RNA sequencing (scRNA-seq) analysis of 6 "para-tumor tissues" samples from scRNA-seq data set GSE184362 and in vitro cell experiments were also conducted.

RESULTS

The HT patients had similar DPP4 serum concentration and activity as the controls. However, the expression and activity of DPP4 was significantly increased in the thyroid of the HT group than in the control group. The scRNA-seq analysis showed that DPP4 expression was significantly increased in the HT group, and mainly expressed in T cells. Further in vitro studies showed that inhibition of lymphocyte DPP4 activity with sitagliptin downregulated the production of inflammatory factors in co-cultured thyroid cells.

CONCLUSION

DPP4 expression was significantly increased in the thyroid of the HT group compared with the control group, and was mainly localized in the lymphocytes. Inhibition of lymphocyte DPP4 activity reduced the production of inflammatory factors in co-cultured thyroid cells. Therefore, inhibition of DPP4 may have a beneficial effect by alleviating inflammatory reactions in HT patients.

The serum concentration and activity of DPP4 is positively related with the severity of hyperthyroidism in patients with Graves' disease

OBJECTIVE

Graves' disease (GD) is an organ-specific autoimmune disease. The production of anti-thyrotropin receptor antibodies (TRAb) is associated with a loss of immune tolerance. Dipeptidyl peptidase-4 (DPP-4) is expressed on multiple immune cells. This study aimed to investigate the relationship between serum concentration/activity of DPP4 and the severity of hyperthyroidism in GD patients.

METHODS

A total of 82 newly diagnosed drug-naive patients with GD hyperthyroidism, 20 patients with non-autoimmune thyrotoxicosis and 122 age- and sex- matched healthy controls were enrolled. The clinical parameters and serum concentration and activity of DPP4 were measured.

RESULTS

The GD group had increased serum concentration and activity of DPP4 than the healthy controls and patients with non-autoimmune thyrotoxicosis, while no significant difference was observed in the latter two groups. Multivariate linear regression indicated that the serum concentration/activity of DPP4 were positively associated with FT3, FT4 and TRAb levels in the GD patients. And the positive association between serum concentration/activity of DPP4 and TRAb was remained even after adjustment for confounding factors (all p < 0.05).

CONCLUSIONS

The GD patients had significantly increased serum concentration/activity of DPP4. And the serum concentration/activity of DPP4 was positively associated with the severity of hyperthyroidism in GD patients.Key messagesThe activity and concentration of DPP4 in patients with Graves' disease were higher than those in healthy controls.There was a significant positive correlation between serum DPP4 concentration and TRAb levels in patients with Graves' disease.In patients with Graves 'disease, serum DPP4 activity was positively correlated with TRAb levels.

Angiogenesis is promoted by exosomal DPP4 derived from 5-fluorouracil-resistant colon cancer cells

Cancer cells can communicate with the tumor microenvironment and contribute to tumor progression. However, the effects of drug-resistant tumor cells on angiogenesis are unclear. Current anti-angiogenic strategies also have limitations and it would be useful to develop novel targets and treatment strategies. Here, our study showed that the conditioned medium and exosomes from 5-FU-resistant colon cancer cells promoted angiogenesis, and we observed that exosomal dipeptidyl peptidase IV (DPP4) was a potent inducer of this angiogenesis. DPP4-enriched exosomes increased periostin (POSTN) expression in human umbilical vein endothelial cells via Twist1 nuclear translocation or activating Smad signaling pathway, while silencing or inhibition of DPP4 neutralized those effects. The in vivo and clinical data indicated that high DPP4 expression was related to tumor progression. These findings indicate that DPP4 may be a target for inhibiting angiogenesis in 5-FU-resistant colon cancer. Furthermore, exosomal DPP4 concentrations may be a useful prognostic marker for colon cancer.

Decreased shedding dipeptidyl peptidase 4 from membrane in Hashimoto's thyroiditis

AIMS

This study aimed to determine the concentration and enzymatic activity of dipeptidyl peptidase 4 (DPP4) in serum and peripheral blood mononuclear cells (PBMCs) from patients with Hashimoto's thyroiditis (HT) and to explore the potential mechanism of the abnormal DPP4 in HT development.

METHODS

A total of 33 newly diagnosed HT patients and 31 age- and sex-matched healthy controls were enrolled. Clinical characteristics and thyroid function data were collected for all participants. Serum DPP4 and kallikrein-related peptidase 5 (KLK5) concentrations were measured by sandwich enzyme-linked immunosorbent assay. DPP4 enzymatic activities in serum and PBMCs were determined by enzymatic assay. DPP4, KLK5 and interferon (IFN)-γ mRNA expression levels in PBMCs were evaluated by quantitative real-time polymerase chain reaction.

RESULTS

Serum DPP4 level and activity were significantly lower in the HT group compared with the control group. However, DPP4 mRNA expression was significantly increased and both serum KLK5 concentration and KLK5 mRNA expression in PBMCs were significantly decreased in HT patients. Correlation analyses revealed that DPP4 concentration was positively correlated with DPP4 enzymatic activity in serum. No significant difference in DPP4 activity was found in PBMCs. DPP4 enzymatic activity in PBMCs was negatively correlated with DPP4 enzymatic activity in serum. IFN-γ mRNA expression in PBMCs was significantly increased in HT patients.

CONCLUSIONS

DPP4 is involved in the development and pathological process of HT. Decreased cleavage of membrane-anchored DPP4 by KLK5 may be responsible for the decreased serum DPP4 levels in HT patients.