Molecular Mechanisms of Parathyroid Disorders in Chronic Kidney Disease

Secondary hyperparathyroidism in chronic kidney disease: pathophysiology, Current treatments and investigational drugs

INTRODUCTION

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD). It begins as an adaptive increase in parathyroid hormone levels to prevent calcium and phosphate derangements. Over time, this condition becomes maladaptive and is associated with increased morbidity and mortality. Current therapies encompass phosphate-lowering strategies, vitamin D analogues, calcimimetics and parathyroidectomy. These approaches harbor inherent limitations, stimulating interest in the development of new drugs for SHPT to overcome these limitations and improve survival and quality of life among CKD patients.

AREAS COVERED

This review delves into the main pathophysiological mechanisms involved in SHPT, alongside the treatment options that are currently available and under active investigation. Data presented herein stem from a comprehensive search conducted across PubMed, Web of Science, ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP) spanning from 2000 onwards.

EXPERT OPINION

The advancements in investigational drugs for SHPT hold significant promise for enhancing treatment efficacy while minimizing side effects associated with conventional therapies. Although several challenges still hinder their adoption in clinical practice, ongoing research will likely continue to expand the available therapeutic options, refine treatment strategies, and tailor them to individual patient profiles.

Coincidence or Causality: Parathyroid Carcinoma in Chronic Kidney Disease-Case Report and Literature Review

Parathyroid carcinoma (PC) associated with primary hyperparathyroidism (PHPT) has been well investigated in recent years. Data regarding PC evolution in secondary hyperparathyroidism (SHPT) due to chronic kidney disease (CKD) are, however, scarce. Most features that raise the suspicion of PC in PHPT are part of the usual SHPT evolution in CKD, mirroring the natural changes undergone by the parathyroid glands. Therefore, pre-surgically establishing the malignant or benign character of the lesions is cumbersome. We present two cases of PC in end-stage renal disease, one of which was bilateral, diagnosed after total parathyroidectomy in a high-volume parathyroid surgery center. A literature review of the data was also performed. A systematic search of the PubMed/MEDLINE database until January 2024 identified 42 cases of PC associated with SHPT. Understanding the PC features in CKD might improve associated bone and mineral disease management, and reduce the risk of metastasis, parathyromatosis, or recurrence. Irradiation, prolonged immunosuppression, long dialysis vintage, and genotype may predispose to the malignant transformation of chronically stimulated parathyroids. Despite postsurgical diagnosis, favorable outcomes occurred when distant metastases were absent, even without "en bloc" resection. Further research is warranted to delineate specific diagnostic and therapeutic approaches tailored to this particular patient subpopulation.

The molecular mechanisms of peptidyl-prolyl cis/trans isomerase Pin1 and its relevance to kidney disease

Pin1 is a member of the peptidyl-prolyl cis/trans isomerase subfamily and is widely expressed in various cell types and tissues. Alterations in Pin1 expression levels play pivotal roles in both physiological processes and multiple pathological conditions, especially in the onset and progression of kidney diseases. Herein, we present an overview of the role of Pin1 in the regulation of fibrosis, oxidative stress, and autophagy. It plays a significant role in various kidney diseases including Renal I/R injury, chronic kidney disease with secondary hyperparathyroidism, diabetic nephropathy, renal fibrosis, and renal cell carcinoma. The representative therapeutic agent Juglone has emerged as a potential treatment for inhibiting Pin1 activity and mitigating kidney disease. Understanding the role of Pin1 in kidney diseases is expected to provide new insights into innovative therapeutic interventions and strategies. Consequently, this review delves into the molecular mechanisms of Pin1 and its relevance in kidney disease, paving the way for novel therapeutic approaches.

Advancing parathyroid anatomy understanding through single-cell RNA sequencing in uremic secondary hyperparathyroidism

This commentary explores the recent application of single-cell RNA sequencing in the study of uremic secondary hyperparathyroidism, shedding light on the cellular dynamics within parathyroid glands. The use of single-cell RNA sequencing reveals new insights into the differentiation processes of chief and oxyphil cells, challenging traditional views and highlighting the potential of this technology in advancing our understanding of parathyroid anatomy.

Effect of Paricalcitol Combined with Cinacalcet on Calcium and Phosphorus Metabolism in Patients Receiving Maintenance Hemodialysis

This study was designed to compare the beneficial effects of paricalcitol combined with or without cinacalcet on calcium and phosphorus metabolism in patients undergoing maintenance hemodialysis (MHD). A total of 140 patients who received MHD in our hospital from March 2021 to March 2022 were randomly divided into a control group (intravenous paricalcitol, n = 70) and a test group (intravenous paricalcitol combined with oral cinacalcet, n = 70). Clinical baseline data and relevant laboratory parameters before treatment were compared. Additionally, calcium, phosphorus, intact parathyroid hormone in serum were measured and compared between the 2 groups before treatment and 1, 2, 3, 4, 5, 6, 9, 10, and 12 months after treatment. As a result, comparison before treatment demonstrated no significant difference in baseline data such as age, sex, and most laboratory parameters between the 2 groups (P > .05), but there was a significant difference in mean corpuscular volume (P < .001). The serum phosphorus level decreased and calcium level increased significantly in the 2 groups after treatment, while the intact parathyroid hormone level showed no significant change within 12 months of treatment (P > .05). In addition, the combined treatment for 6-12 months caused a much lower phosphorus level (P < .05) and higher calcium level (P < .05) than the treatment with paricalcitol alone, and the difference increased with the extension of treatment time. Collectively, paricalcitol combined with cinacalcet, which is more effective than paricalcitol alone, has a positive effect on calcium and phosphorus metabolism in patients receiving MHD.

Frontiers in Bone Metabolism and Disorder in Chronic Kidney Disease

Chronic Kidney Disease (CKD) is a progressive condition that affects 10-15% of the adult population, a prevalence expected to increase worldwide [...].

Misdiagnosis of chronic kidney disease and parathyroid hormone testing during the past 16 years

Chronic kidney disease (CKD) is a prevalent pathological condition worldwide. Parathyroid hormone (PTH) is an important index related to bone metabolism in CKD patients and has not received enough attention. This study was performed to investigate the incidence and diagnostic rate of CKDin hospital as well as PTH testing and treatment for secondary hyperparathyroidism (SHPT) in patients with stage 3 to 5 CKD. The data of patients who visited Zhejiang Provincial People's Hospital from February 2006 to April 2022 were retrieved from the hospital database. All data were divided into three subgroups using PTH testing and SHPT treatment as major comparative indicators for analysis. The data were then analyzed for overall PTH testing, CKD incidence, and diagnostic rate. Among 5,301,391 patients, the incidence of CKD was 13.14%. The missed diagnosis rate for CKD was 65.76%. The total PTH testing rate was 1.22%, of which 15.37% of PTH testing was performed in patients with stage 3 to 5 CKD. The overall diagnosis rate of SHPT in patients with stage 3 to 5 CKD was 31.0%. The prophylactic medication rate was 7.4%, and the rate of post-diagnostic drug therapy was 22.2% in patients who underwent SHPT treatment. The high misdiagnosis rate and low PTH testing rate of CKD requires prompt attention from clinicians. SHPT treatment should be considered especially in patients with stage 3 to 5 CKD.

Identification of key biomarkers based on the proliferation of secondary hyperparathyroidism by bioinformatics analysis and machine learning

Objective

Secondary hyperparathyroidism (SHPT) is a frequent complication of chronic kidney disease (CKD) associated with morbidity and mortality. This study aims to identify potential biomarkers that may be used to predict the progression of SHPT and to elucidate the molecular mechanisms of SHPT pathogenesis at the transcriptome level.

Methods

We analyzed differentially expressed genes (DEGs) between diffuse and nodular parathyroid hyperplasia of SHPT patients from the GSE75886 dataset, and then verified DEG levels with the GSE83421 data file of primary hyperparathyroidism (PHPT) patients. Candidate gene sets were selected by machine learning screens of differential genes and immune cell infiltration was explored with the CIBERSORT algorithm. RcisTarget was used to predict transcription factors, and Cytoscape was used to construct a lncRNA-miRNA-mRNA network to identify possible molecular mechanisms. Immunohistochemistry (IHC) staining and quantitative real-time polymerase chain reaction (qRT-PCR) were used to verify the expression of screened genes in parathyroid tissues of SHPT patients and animal models.

Results

A total of 614 DEGs in GSE75886 were obtained as candidate gene sets for further analysis. Five key genes (USP12, CIDEA, PCOLCE2, CAPZA1, and ACCN2) had significant expression differences between groups and were screened with the best ranking in the machine learning process. These genes were shown to be closely related to immune cell infiltration levels and play important roles in the immune microenvironment. Transcription factor ZBTB6 was identified as the master regulator, alongside multiple other transcription factors. Combined with qPCR and IHC assay of hyperplastic parathyroid tissues from SHPT patients and rats confirm differential expression of USP12, CIDEA, PCOLCE2, CAPZA1, and ACCN2, suggesting that they may play important roles in the proliferation and progression of SHPT.

Conclusion

USP12, CIDEA, PCOLCE2, CAPZA1, and ACCN2 have great potential both as biomarkers and as therapeutic targets in the proliferation of SHPT. These findings suggest novel potential targets and future directions for SHPT research.

The Mediation Effect of Peripheral Biomarkers of Calcium Metabolism and Chronotypes in Bipolar Disorder Psychopathology

Calcium (Ca++) metabolism may be impaired in several psychiatric diseases. We hypothesize that calcium imbalance might also correlate with a specific chronotype and could be recognized as a marker of illness severity in bipolar disorder (BD). We aimed to (1) identify the association between calcium imbalance and a specific chronotype in a cohort of BD patients, and (2) test the mediation role of high parathyroid hormone (PTH) levels towards a specific chronotype and illness severity in BD patients. Patients’ socio-demographic and clinical characteristics were collected with an ad-hoc schedule. We administered the Hamilton Depression Rating Scale (HAM-D), the Hamilton Rating Scale for Anxiety (HAM-A), the Young Mania Rating Scale (YMRS), and the Morningness Eveningness Questionnaire (MEQ). 100 patients affected by BD were recruited. The Kruskal-Wallis test showed a significant difference between the three MEQ groups in PTH levels (p < 0.001) and vitamin D levels (p = 0.048) but not in Ca++ levels (p = 0.426). Dwass-Steel-Critchlow-Fligner Pairwise analyses performed concerning three MEQ groups revealed significantly higher scores on PTH levels in MEQ-E subjects compared to MEQ-M and MEQ-I (in both cases, p < 0.001). No differences emerged between calcium levels among the three chronotypes. The mediation analysis has shown that elevated PTH levels are directly influenced by more severe HAM-A, HAM-D, and YMRS scores. MEQ-E could be a marker related to BD and predispose to various factors influencing mood symptoms. The combination of vitamin D therapy in MEQ-E may help to improve prognosis in this subtype of patients affected by BD.

Role of Sclerostin in Cardiovascular Disease

Sclerostin is most recognized for its role in controlling bone formation but is also expressed in the heart, aorta, coronary, and peripheral arteries. This review summarizes research on sclerostin's role in cardiovascular disease. Rodent studies have found sclerostin to be expressed at sites of arterial calcification. In contrast, aortic sclerostin was reported to be downregulated in a mouse model of abdominal aortic aneurysm, and transgenic upregulation or administration of sclerostin was found to prevent abdominal aortic aneurysm and atherosclerosis formation. Sclerostin deficiency was reported to stimulate cardiac rupture in one rodent model. In humans, 7 of 11 studies reported a significant association between high serum sclerostin and high carotid intima media thickness. Ten of 15 studies reported a significant association between high serum sclerostin and severe arterial calcification. Twelve of 14 studies reported a significant association between high serum sclerostin and high arterial stiffness or atherosclerosis severity. Four of 9 studies reported a significant association between high serum sclerostin and high risk of cardiovascular events. A meta-analysis of randomized controlled trials suggested that administration of the sclerostin blocking antibody romosozumab did not significantly increase the risk of major adverse cardiovascular events (risk ratio, 1.14 [95% CI, 0.83-1.57]; P=0.54) or cardiovascular death (risk ratio, 0.92 [95% CI, 0.53-1.59]; P=0.71). Human genetic studies reported variants predisposing to low arterial sclerostin expression were associated with a high risk of cardiovascular events. Overall, past research suggests a cardiovascular protective role of sclerostin but findings have been inconsistent, possibly due to variations in study design, the unique populations and models studied, and the heterogeneous methods used.