Are oxyphil cells responsible for the ineffectiveness of cinacalcet hydrochloride in haemodialysis patients?

Relationship between parathyroid adenoma size, weight and histological subtypes with perioperative serum levels

AIMS

This study aims to identify associations between parathyroid adenoma (PTA) characteristics (histology, weight and size) with the change in parathyroid hormone (PTH) and calcium levels.

METHODS

A historical cohort study was conducted on adult patients with solitary PTA removed in the Gold Coast Health Precinct, Australia, between 2017 and 2022.

RESULTS

PTA weight is correlated with the change in day 1 PTH level (r=0.26, p=0.036), the change in day 1 corrected calcium level (r=0.20, p=0.033), and the change in follow-up corrected calcium level (r=0.47, p<0.001). The largest dimension (size) of PTA is also correlated with the change in day 1 PTH (r=0.30, p=0.011) and the change in follow-up corrected calcium level (r=0.40, p<0.001). Adjusted for age and gender, a statistically significant negative correlation was found between day 1 PTH level and adenoma size, resulting in a 0.5% change in size for every percentage change in PTH level (equating to a 5.0% increase in variance explained, p=0.038). Similarly, a negative correlation was identified in day 1 corrected calcium levels and weight, with a 4.7% change in weight for every percentage of change in day 1 corrected calcium level (an increase of 5.6% variance explained, p=0.010). In addition, a negative correlation was identified, where every 3.1% change in size (an increase of 17.4% variance explained, p<0.001) and 7.6% change in weight (an increase of 22.7% variance explained, p<0.001) was seen with every percentage change in follow-up corrected calcium levels. Clear-cell PTA had the most significant percentage fall in day 1 corrected calcium levels compared with other PTA subtypes (p=0.007).

CONCLUSIONS

Preoperative calcium and PTH levels correlate with PTA weight and size. The degree of change in postoperative corrected calcium levels behaved differently in the clear-cell subtype.

High lymphocyte signature genes expression in parathyroid endocrine cells and its downregulation linked to tumorigenesis

BACKGROUND

To date, because of the difficulty in obtaining normal parathyroid gland samples in human or in animal models, our understanding of this last-discovered organ remains limited.

METHODS

In the present study, we performed a single-cell transcriptome analysis of six normal parathyroid and eight parathyroid adenoma samples using 10 × Genomics platform.

FINDINGS

We have provided a detailed expression atlas of parathyroid endocrine cells. Interestingly, we found an exceptional high expression levels of CD4 and CD226 in parathyroid endocrine cells, which were even higher than those in lymphocytes. This unusual expression of lymphocyte markers in parathyroid endocrine cells was associated with the depletion of CD4 T cells in normal parathyroid glands. Moreover, CD4 and CD226 expression in endocrine cells was significantly decreased in parathyroid adenomas, which was associated with a significant increase in Treg counts. Finally, along the developmental trajectory, we discovered the loss of POMC, ART5, and CES1 expression as the earliest signature of parathyroid hyperplasia.

INTERPRETATION

We propose that the loss of CD4 and CD226 expression in parathyroid endocrine cells, coupled with an elevated number of Treg cells, could be linked to the pathogenesis of parathyroid adenoma. Our data also offer valuable information for understanding the noncanonical function of CD4 molecule.

FUNDING

This work was supported by the National Key R&D Program of China (2022YFA0806100), National Natural Science Foundation of China (82130025, 82270922, 31970636, 32211530422), Shandong Provincial Natural Science Foundation of China (ZR2020ZD14), Innovation Team of Jinan (2021GXRC048) and the Outstanding University Driven by Talents Program and Academic Promotion Program of Shandong First Medical University (2019LJ007).

Integrated transcriptomic and proteomic analyses for the characterization of parathyroid oxyphil cells in uremic patients

Chief cells are the predominant cells in parathyroid glands of healthy adults; however, parathyroid oxyphil cells, whose function is unknown, increase dramatically in patients with secondary hyperparathyroidism (SHPT). Calcitriol and calcimimetics are the most powerful treatments for SHPT, while the mechanisms leading to calcitriol or calcimimetic resistance in oxyphil cell-predominant SHPT are unknown. Here we used transcriptomic and proteomic techniques to characterize oxyphil cells by comparing the differences between chief and oxyphil cell nodules of parathyroid glands in uremic patients. Compared to chief cell nodules, the most marked expression increases in oxyphil cell nodules were for mitochondrion-associated proteins. The mitochondria number and mitochondrial DNA content were also significantly increased in oxyphil cell nodules. Moreover, oxyphil cell nodules expressed parathyroid-specific factors, and exhibited lower levels of proliferation-related proteins but higher synthesis and secretion level of parathyroid hormone (PTH). The protein expression of SHPT-regulating factors, including vitamin-D receptor, calcium-sensing receptor and Klotho, were significantly downregulated in oxyphil cell nodules. Therefore, oxyphil cells characterized by enrich mitochondria in uremic patients showed higher synthesis and secretion of PTH but lower expression of SHPT regulators than chief cells, which may contribute to the pathophysiology of SHPT and the treatment resistance to calcitriol and calcimimetics.

Relationship between parathyroid oxyphil cell proportion and clinical characteristics of patients with chronic kidney disease

BACKGROUND

Parathyroid glands consist of chief cells and oxyphil cells. The parathyroid oxyphil cell proportion increased dramatically in patients with chronic kidney disease (CKD). The importance of the oxyphil cell in the treatment of secondary hyperparathyroidism (SHPT) has been enhanced in recent years. The aim of this study was to explore the possible relationship between parathyroid oxyphil cell proportion and clinical features of patients with CKD.

METHODS

From December 2010 to December 2018, 78 consecutive patients with CKD 5 who underwent parathyroidectomy (PTX) were reviewed. None of the patients had used Cinacalcet. Patients were divided into two groups according to their parathyroid oxyphil cell proportion. The mean parathyroid oxyphil cell proportion of all the patients was obtained. Group 1 consisted of 37 patients, the parathyroid oxyphil cell proportion of whom was more than or equal to mean proportion. Group 2 consisted of 41 patients, the parathyroid oxyphil cell proportion of whom was less than mean proportion. The demographic and biochemical data of the two groups were compared.

RESULTS

Preoperative parathyroid hormone (PTH) and total weight of removed parathyroid glands in the patients of group 1were less than those in group 2. There was no difference between the two groups in terms of preoperative calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), age and dialysis years.

CONCLUSION

The parathyroid oxyphil cell proportion was associated with preoperative PTH and total weight of removed parathyroid glands in the patients with CKD. Patients with more parathyroid oxyphil proportion had lower preoperative PTH level and smaller total weight of the removed parathyroid glands.