PD-L1 and PD-1 expression in thyroid follicular epithelial dysplasia: Hashimoto thyroiditis related atypia and
Emma Pakkanen1,2, David Kalfert3, Maarit Ahtiainen4
1Pathology, Fimlab Laboratories, Tampere, Finland.
Abstract:
Programmed cell death ligand (PD-L1)/PD-1 expression has been studied in a variety of cancers and blockage of PD-L1/PD-1 pathway is a cornerstone of immunotherapy. We studied PD-L1/PD-1 immunohistochemical expression in 47 thyroid gland specimens in groups of (1) Hashimoto thyroiditis (HT) only; (2) HT and follicular epithelial dysplasia (FED); and (3) HT, FED, and papillary thyroid carcinoma (PTC). PD-1 positivity was found in immune cells, namely in lymphocytes, macrophages, and plasma cells with mean values for lymphocytes and macrophages 9% in HT group, 4% in FED group, and 4% in PTC group. PD-L1 positivity was identified in both immune cells and in the normal epithelial cells. In the HT group, mean PD-L1 staining on immune cells was 6%, in FED group 5%, and in PTC group 7%. The mean PD-L1 staining on the epithelial cells in the inflammatory parenchyma was 11.7% in HT, 13.4% in FED, and 8.3% in PTC group. The mean PD-L1 staining of FED foci was 47.2% in FED group and 33.6% in PTC group. The mean tumor proportion score (TPS) was 10.4%, and the mean combined positive score (CPS) was 15.5. At the moment, PTC is not a target of immunotherapy. However, understanding the complex issue of concurrent inflammation and autoimmunity can importantly influence the cancer treatment in future.
Insights
This study examined programmed cell death ligand (PD-L1) and PD-1 expression in thyroid tissues. While papillary thyroid carcinoma (PTC) isn't currently an immunotherapy target, findings may inform future cancer treatments.
Area of Science:
- Immunology
- Oncology
- Pathology
Background:
- Programmed cell death ligand (PD-L1)/PD-1 pathway is crucial in cancer immunotherapy.
- Expression patterns in thyroid gland conditions require further investigation.
Purpose of the Study:
- To investigate PD-L1 and PD-1 immunohistochemical expression in Hashimoto thyroiditis (HT), follicular epithelial dysplasia (FED), and papillary thyroid carcinoma (PTC).
- To explore the potential influence of concurrent inflammation and autoimmunity on future cancer treatment strategies.
Main Methods:
- Analysis of 47 thyroid gland specimens categorized into three groups: HT only, HT with FED, and HT with FED and PTC.
- Immunohistochemical staining for PD-1 and PD-L1 on immune cells and epithelial cells.
- Calculation of mean expression values, tumor proportion score (TPS), and combined positive score (CPS).
Main Results:
- PD-1 was primarily expressed on lymphocytes and macrophages.
- PD-L1 expression was observed on both immune and epithelial cells, with notable high staining in FED foci.
- Mean TPS was 10.4% and mean CPS was 15.5 in the PTC group.
Conclusions:
- PD-L1 expression is significantly elevated in follicular epithelial dysplasia foci within the context of Hashimoto thyroiditis and papillary thyroid carcinoma.
- Understanding the interplay of inflammation and autoimmunity in thyroid tissue is vital for future cancer therapy development.
- Papillary thyroid carcinoma is not currently a target for PD-1/PD-L1-based immunotherapy.
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