Phosphatonins: From Discovery to Therapeutics

ObjectivePhosphate is crucial for cell signaling, energy metabolism, nucleotide synthesis, and bone mineralization. The gut-bone-parathyroid-kidney axis is influenced by parathyroid hormone, 1,25-dihydroxyvitamin D, and phosphatonins, especially fibroblast growth factor 23 (FGF23). These hormones facilitate maintenance of phosphate homeostasis. This review summarizes current knowledge regarding the phosphate homeostasis, phosphatonin pathophysiology, and clinical implications of FGF23-related hypophosphatemic disorders, with specific focus on burosumab treatment.MethodA focused literature search of PubMed was conducted.ResultsPhosphatonins including FGF23, secreted frizzled-related protein 4, matrix extracellular phosphoglycoprotein, and fibroblast growth factor 7 play a pathogenic role in several hypophosphatemic disorders. Excess FGF23 inhibits sodium-dependent phosphate cotransporters (NaPi-2a and NaPi-2c), resulting in hyperphosphaturia and hypophosphatemia. Additionally, FGF23 suppresses 1,25-dihydroxyvitamin D synthesis in the proximal renal tubule, and thus, it indirectly inhibits intestinal phosphate absorption. Disorders of FGF23-related hypophosphatemia include X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets, fibrous dysplasia/McCune-Albright syndrome, and tumor-induced osteomalacia (TIO). Complications of conventional therapy with oral phosphate and vitamin D analogs comprise gastrointestinal distress, hypercalcemia, nephrocalcinosis, and secondary/tertiary hyperparathyroidism. In both children and adults with XLH and TIO, the anti-FGF23 antibody burosumab exhibits a favorable safety profile and is associated with healing of rickets in affected children and improvement of osteomalacia in both children and adults.ConclusionThe treatment paradigm for XLH and TIO is changing based on data from recent clinical trials. Research suggest that burosumab is effective and safe for pediatric and adult patients with XLH or TIO.     

KCNJ5 Mutation Contributes to Complete Clinical Success in Aldosterone-Producing Adenoma: A Study From a Single Center

ObjectiveThe KCNJ5 mutation is the most frequent mutation in aldosterone-producing adenoma (APA). We aimed to illustrate the relationship between KCNJ5 and prognosis after adrenalectomy as a guide for further treatment.MethodsOur study included 458 patients with APA. Tumor tissues were screened for somatic mutations in KCNJ5 hot-spot regions. We performed a retrospective analysis to identify correlations between KCNJ5 and clinical outcomes in 334 patients with adrenal venous sampling lateralization.ResultsSomatic KCNJ5 mutations were identified in 324 of 458 patients with APA (70.7%). Compared with the KCNJ5-wild type patients, patients with KCNJ5 mutations were younger, had a higher proportion of women, and had shorter durations of hypertension, lower body mass indexes (BMIs), and lower systolic blood pressure values (P < .05). During follow-up, among the 334 patients with APA with adrenal venous sampling lateralization, 320 (95.8%) presented complete biochemical success and 187 (56.0%) presented complete clinical success. One hundred eighty-seven patients with primary aldosteronism who achieved complete clinical success presented the following characteristics: age <40 years (78.7%), BMI <24 kg/m² (71.0%), hypertension duration <5 years (78.4%), females (66.9%), and KCNJ5 mutation (65.5%). A multivariate logistic regression analysis identified BMI, hypertension duration, and KCNJ5 mutation as independent predictors of complete clinical success.ConclusionThe prevalence of KCNJ5 mutations was 70.7%. KCNJ5 mutation is a protective factor of complete clinical success, while BMI and hypertension duration were risk factors of incomplete clinical success.     

Proteomics-based synapse characterization: From proteins to circuits

The highly heterogeneous nature of neuronal cell types and their connections presents a major challenge to the characterization of neural circuits at the protein level. New approaches now enable an increasingly sophisticated dissection of cell type- and cellular compartment-specific proteomes, as well as the profiling of the protein composition of specific synaptic connections. Here, we provide an overview of these approaches and discuss how they hold considerable promise toward unravelling the molecular mechanisms of neural circuit formation and function. Finally, we provide an outlook of technological developments that may bring the characterization of synaptic proteomes at the single-synapse level within reach.     

The role of amino acid metabolism alterations in pancreatic cancer: From mechanism to application

The incidence of pancreatic cancer is increasing in both developed and developing Nations. In recent years, various research evidence suggested that reprogrammed metabolism may play a key role in pancreatic cancer tumorigenesis and development. Therefore, it has great potential as a diagnostic, prognostic and therapeutic target. Amino acid metabolism is deregulated in pancreatic cancer, and changes in amino acid metabolism can affect cancer cell status, systemic metabolism in malignant tumor patients and mistakenly involved in different biological processes including stemness, proliferation and growth, invasion and migration, redox state maintenance, autophagy, apoptosis and even tumor microenvironment interaction. Generally, the above effects are achieved through two pathways, energy metabolism and signal transduction. This review aims to highlight the current research progress on the abnormal alterations of amino acids metabolism in pancreatic cancer, how they affect tumorigenesis and development of pancreatic cancer and the application prospects of them as diagnostic, prognostic and therapeutic targets.     

Osteoporosis Treatment After Osteoporotic Fractures: Data From a Single Medical Center

ObjectiveMost patients do not receive osteoporosis treatment after osteoporotic fracture. This study reviewed osteoporosis treatment after osteoporotic fractures in a center without a Fracture Liaison Service.MethodsWe identified all patients with hip, vertebral, humeral or radial fractures, evaluated in Meir Medical Center, in 2017. The exclusion criteria were not a Clalit Health Services member, high-energy fracture or 30-day postoperative mortality. The primary endpoint was osteoporosis drugs issued within 12 months of fracture. Secondary endpoints included bone densitometry and 1-year mortality.ResultsFive-hundred-eighty-two patients (average age 78.6 ± 11.1 years, 75.8% women) were included. There were 321 (55.5%) hip, 84 (14.1%) humeral, 33 (5.6%) vertebral, and 144 (24.7%) radial fractures. Osteoporosis drugs were issued to 26.5% of the patients; those with humeral fractures received the least (21.4%) and vertebral, the most (30.3%; P = .51). Bone densitometry was performed in 23.2% of patients. One-year mortality after hip fracture was 12.1%, followed by humeral (3.6%; P < .05). Logistic regression showed that previous treatment (odds ratio [OR] = 7.4; 95% confidence interval [CI] 3.6–15.2), bone densitometry (OR = 4.4; 95% CI 2.6–7.4) and endocrinology visit (OR = 2.6; 95% CI, 1.4–4.6) were the most important factors associated with treatment.ConclusionFewer than one third of patients received pharmacotherapy within 1 year after fracture. Because pharmacotherapy reduces future fractures and mortality, we recommend that medical staff who care for patients with fracture adopt practical and effective strategies to increase treatment rates among patients with osteoporotic fractures.     

Inpatient Perioperative Euglycemic Diabetic Ketoacidosis Due to Sodium-Glucose Cotransporter-2 Inhibitors – Lessons From a Case Series and Strategies to Decrease Incidence

ObjectiveTo identify clinical characteristics and factors associated with the development of euglycemic diabetic ketoacidosis (eDKA), and develop suitable strategies to reduce such events.MethodsElectronic health record (EHR) data were extracted to identify all patients between December 1, 2013, and March 30, 2021, who underwent surgical procedures and had been prescribed a sodium-glucose cotransporter 2 inhibitor (SGLT2i) before these procedures. The resulting list was streamlined to a subset of patients who either had diabetic ketoacidosis (DKA) listed as a hospital diagnosis, postoperative serum bicarbonate ≤ 16 mmol/L, or postoperative serum pH ≤ 7.20. Clinical documentation and laboratory data were reviewed to determine the patients with eDKA.ResultsA total of 2183 procedures conducted on 1307 patients, met the inclusion criteria with the majority (1726, 79.1%) being nonemergent patients. Among 1307 patients, 625 (47.8%) were prescribed empagliflozin, 447 (34.2%) canagliflozin, 214 (16.4%) dapagliflozin, and 21 (1.6%) ertugliflozin, respectively. A total of 8 incidences pertaining to eDKA were noted for 8 unique patients; 5 had undergone emergency surgery whereas 3 had undergone nonemergent procedures. In the 3 nonemergent cases, only 1 patient had received counseling to stop the SGLT2i 3 days before the procedure. In perioperative patients who were prescribed an SGLT2i over 6 years, the incidence of eDKA was 0.17% and 1.1% for nonemergent and emergent procedures, respectively.ConclusionEuglycemic DKA was rare in patients undergoing nonemergent procedures, likely because of preoperative instructions to stop their SGLT2i 3 days before the procedure. Euglycemic DKA was more likely to occur in patients undergoing emergency surgery when the SGLT2i could not be prophylactically stopped.     

Transition From Pediatric to Adult Care for Individuals With Type 1 Diabetes: Opportunities and Challenges

ObjectivesType 1 diabetes (T1D) is a chronic disease with patients across the age spectrum that has high potential for morbidity and mortality. Unfortunately, patients transitioning from pediatric to adult care continue to demonstrate worsened glycemic control in part due to lack of understanding of transition of care best practices.MethodsThis review highlights the impact of existing transition of care interventions, assessment tools, and other recently published strategies for providers to consider to improve care of adolescent and young adult (AYA) patients with T1D in both hospital- and clinic-based settings.ResultsMany barriers impact patients with T1D during the transition period and disparities by race, sex, insurance status, and comorbid illness persist. As diabetic care continues to evolve and the prevalence of adolescents and young adults living with T1D increases, an intentional approach to transition of care is more pressing than ever. While current literature on transition of care models is limited, many show promise in improving clinic attendance and decreasing hospitalization. There are critical discussions that providers should lead with AYA patients to improve their outcomes and increase diabetes self-management, such as re-addressing carbohydrate counseling, sleep hygiene, and reproductive planning.ConclusionWhile further research on transition of care is needed, many care models offer the promise of improved T1D outcomes, enhancements in our approach to care, and increased value for our health care system at large.     

Minimizing Venous Thromboembolism in Feminizing Hormone Therapy: Applying Lessons From Cisgender Women and Previous Data

ObjectiveTo review he impact of estrogen-containing feminizing hormone regimens on transgender individuals’ risk for VTE.MethodsWe evaluated VTE risk by screening 1170 relevant studies published from 1994 to 2020, focusing on meta-analysis data.ResultsThe type of oral estrogen, route of administration, patient demographics, and comorbidities may affect the risk of VTE. Venous thrombosis is the most common vascular complication associated with HT.ConclusionConjugated equine estrogens and 17-β estradiol appear to be safer than oral ethinyl estradiol. Transdermal estrogen formulations appear to be the least thrombogenic estrogens. Estrogens used concomitantly with progestins increase the risk of VTE compared to estrogens alone.To date, there are no data to demonstrate the benefit of holding HT prior to vaginoplasty or other gender affirming surgeries. For most young, healthy transgender women, there is little risk of VTE with HT, while older patients with risk factors should be discussed case by case.     

Soluble ANPEP Released From Human Astrocytes as a Positive Regulator of Microglial Activation and Neuroinflammation: Brain Renin–Angiotensin System in Astrocyte–Microglia Crosstalk

Astrocytes are major supportive glia and immune modulators in the brain; they are highly secretory in nature and interact with other cell types via their secreted proteomes. To understand how astrocytes communicate during neuroinflammation, we profiled the secretome of human astrocytes following stimulation with proinflammatory factors. A total of 149 proteins were significantly upregulated in stimulated astrocytes, and a bioinformatics analysis of the astrocyte secretome revealed that the brain renin–angiotensin system (RAS) is an important mechanism of astrocyte communication. We observed that the levels of soluble form of aminopeptidase N (sANPEP), an RAS component that converts angiotensin (Ang) III to Ang IV in a neuroinflammatory milieu, significantly increased in the astrocyte secretome. To elucidate the role of sANPEP and Ang IV in neuroinflammation, we first evaluated the expression of Ang IV receptors in human glial cells because Ang IV mediates biological effects through its receptors. The expression of angiotensin type 1 receptor was considerably upregulated in activated human microglial cells but not in human astrocytes. Moreover, interleukin-1β release from human microglial cells was synergistically increased by cotreatment with sANPEP and its substrate, Ang III, suggesting the proinflammatory action of Ang IV generated by sANPEP. In a mouse neuroinflammation model, brain microglial activation and proinflammatory cytokine expression levels were increased by intracerebroventricular injection of sANPEP and attenuated by an enzymatic inhibitor and neutralizing antibody against sANPEP. Collectively, our results indicate that astrocytic sANPEP–induced increase in Ang IV exacerbates neuroinflammation by interacting with microglial proinflammatory receptor angiotensin type 1 receptor, highlighting an important role of indirect crosstalk between astrocytes and microglia through the brain RAS in neuroinflammation.     

Relationship between hepatic and mitochondrial ceramides: a novel in vivo method to track ceramide synthesis

Ceramides (CERs) are key intermediate sphingolipids implicated in contributing to mitochondrial dysfunction and the development of multiple metabolic conditions. Despite the growing evidence of CER role in disease risk, kinetic methods to measure CER turnover are lacking, particularly using in vivo models. The utility of orally administered ¹³C₃, ¹⁵N l-serine, dissolved in drinking water, was tested to quantify CER 18:1/16:0 synthesis in 10-week-old male and female C57Bl/6 mice. To generate isotopic labeling curves, animals consumed either a control diet or high-fat diet (HFD; n = 24/diet) for 2 weeks and varied in the duration of the consumption of serine-labeled water (0, 1, 2, 4, 7, or 12 days; n = 4 animals/day/diet). Unlabeled and labeled hepatic and mitochondrial CERs were quantified using liquid chromatography tandem MS. Total hepatic CER content did not differ between the two diet groups, whereas total mitochondrial CERs increased with HFD feeding (60%, P < 0.001). Within hepatic and mitochondrial pools, HFD induced greater saturated CER concentrations (P < 0.05) and significantly elevated absolute turnover of 16:0 mitochondrial CER (mitochondria: 59%, P < 0.001 vs. liver: 15%, P = 0.256). The data suggest cellular redistribution of CERs because of the HFD. These data demonstrate that a 2-week HFD alters the turnover and content of mitochondrial CERs. Given the growing data on CERs contributing to hepatic mitochondrial dysfunction and the progression of multiple metabolic diseases, this method may now be used to investigate how CER turnover is altered in these conditions.     

Antidiabetic Medications for Type 2 Diabetics with Nonalcoholic Fatty Liver Disease: Evidence From a Network Meta-Analysis of Randomized Controlled Trials

ObjectiveType 2 diabetes mellitus and nonalcoholic fatty liver disease (NAFLD) are closely related, and antidiabetic medications have been shown to be potential therapeutics in NAFLD. Using a network meta-analysis, we sought to examine the effectiveness of antidiabetic agents for the treatment of NAFLD in patients with type 2 diabetes mellitus.MethodsMedline and Embase were searched for randomized controlled trials relating to the use of antidiabetic agents, including sodium-glucose transport protein 2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor agonists, and peroxisome proliferator-activated receptor gamma (PPARγ) agonists, biguanides, sulfonylureas and insulin, on NAFLD in patients with diabetes. The p-score was used as a surrogate marker of effectiveness.ResultsA total of 14 articles were included in the analysis. PPARγ agonists were ranked as the best treatment in steatosis reduction, resulting in the greatest reduction of steatosis. There was statistical significance between PPARγ agonists [mean difference (MD): ?6.02%, confidence interval (CI): ?10.37% to ?1.67%] and SGLT2 inhibitors (MD: ?2.60%, CI: ?4.87% to ?0.33%) compared with standard of care for steatosis reduction. Compared with PPARγ agonists, SGLT2 inhibitors resulted in a statistical significant reduction in fibrosis (MD: ?0.06, CI: ?0.10 to ?0.02). Body mass index reduction was highest in SGLT2 inhibitors and glucagon-like peptide-1 receptor agonists. Additionally, SGLT2 inhibitors were ranked as the best treatment for increasing high-density lipoprotein and reducing low-density lipoprotein.ConclusionGlucagon-like peptide-1 receptor agonists and SGLT2 inhibitors were suitable alternatives for the treatment of NAFLD in those with type 2 diabetes mellitus with a reduction in body mass index, fibrosis, and steatosis. SGLT2 inhibitors also have the added benefit of lipid modulation.     

Increased Bone Mineral Density in Male Patients With Idiopathic Hypogonadotropic Hypogonadism Who Undergo Sex Hormone Therapy: Findings From Cross-Sectional and Longitudinal Studies

ObjectiveThis retrospective observational study assessed the long-term impact of pulsatile gonadotropin-releasing hormone, combined gonadotropin, or testosterone replacement therapy on total hip, femoral, and lumbar bone mineral density (BMD) and Z-scores in adult men with idiopathic hypogonadotropic hypogonadism (IHH).MethodsIn the cross-sectional study, 69 patients were allocated to untreated (n = 42) and treated (n = 27) groups. The untreated group included IHH patients without hormone therapy history, while the treated group included age- and body mass index-matched patients who had received hormone therapy for at least 5 years. The longitudinal study included 53 IHH patients, and their hip and lumbar BMDs were measured several times during hormone therapy. We then evaluated the changes in their BMD.ResultsOur cross-sectional study showed that the treated group had a significantly higher BMD and Z-score for total hip, femoral neck, and lumbar spine (P < 0.001 for all) than the untreated group, and the average bone mass even reached the age-matched normal range. The prevalence of low BMD was 80.95% and 11.11% in untreated and treated groups, respectively. In the longitudinal study (N = 53), the total hip, femoral neck, and lumbar spine BMD gradually increased during treatment. The lumbar spine showed a greater increment in BMD compared with the total hip and femoral neck (P < 0.05).ConclusionSex hormone therapy improved hip and lumbar spine BMD and Z-scores in patients with IHH. The lumbar spine showed a greater improvement in BMD compared with the total hip and femoral neck.     

Long-Term Adverse Effects of Cigarette Smoking on the Incidence Risk of Metabolic Syndrome With a Dose-Response Relationship: Longitudinal Findings of the Korean Genome and Epidemiology Study Over 12 Years

ObjectiveTo investigate the association between the intensity and cumulative dose of cigarette smoking and incidence risk of metabolic syndrome (MetS) in a longitudinal prospective study over 12 years of follow-up.MethodsThis study included 3151 men aged 40 to 69 years from the Korean Genome and Epidemiology Study. MetS was defined as proposed by the Joint Interim Statement of the Circulation 2009 report. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) for incidence risk of MetS were calculated from 2 separate perspectives: (1) number of cigarettes smoked per day (intensity) and (2) total number of cigarettes smoked over a person’s lifetime (cumulative dose) using multiple logistic regression analyses.ResultsIn comparison with never smokers, the HRs (95% CIs) were 0.97 (0.78-1.21) for former smokers and 1.50 (1.07-2.01) with 0 to 9 cigarettes per day, 1.66 (1.34-2.06) with 10 to 19 cigarettes per day, and 1.75 (1.34-2.29) with ≥20 cigarettes per day for current smokers after adjusting for confounding variables. Similar positive dose-response relationships were also observed when the cumulative dose of cigarette smoking was categorized into former and current smokers, with subcategories of <20 and >20 pack-years (PYs). The HRs (95% CIs) were 0.99 (0.77-1.23) for <20 PYs and 0.99 (0.77-1.28) for ≥20 PYs for former smokers and 1.63 (1.32-2.02) for <20 PYs and 1.67 (1.30-2.14) for ≥20 PYs for current smokers after adjusting for the same covariables.ConclusionCigarette smoking intensity and cumulative dose were both found to be positively associated with the incidence risk of MetS in men.     

The Prolactin per Unit Tumor Volume Ratio Accurately Distinguishes Prolactinomas From Secondary Hyperprolactinemia due to Stalk Effect

ObjectiveThe prolactin levels alone are insufficient to distinguish between some cases of prolactinomas and stalk effect. We aimed to formally characterize the relationship between serum prolactin and prolactinoma volume, determine a cutoff for prolactin/mm³ that accurately distinguishes prolactinomas from stalk effect, and validate this cutoff in a cohort selected to include ambiguous prolactin values ranging from 50 to 150 ng/mL.MethodsWe used the Research Patient Data Registry and transsphenoidal surgery database in our institution to retrospectively identify adult patients with clinically nonfunctioning (NF) tumors (primary analysis, n = 279; validation cohort, n = 10) and prolactinomas (primary analysis, n = 94; validation cohort, n = 18). Solid tumor volumes were measured by Visage 7 software, and cystic foci within tumors were excluded.ResultsProlactin levels were significantly correlated with prolactinoma volume (r² = 0.801) but were not a relevant predictor of NF tumor size (r² = 0.015). The prolactin/mm³ values did not overlap between NF tumors (median, 0.016; interquartile range, 0.009-0.028) and prolactinomas (median, 0.551; interquartile range, 0.265-0.845) (P < .0001). A cutoff of 0.065 ng/mL)/mm³ correctly discriminated between prolactinomas and NF tumors in all 401 patients in the primary analysis and validation cohort.ConclusionThe prolactin/volume ratio correctly distinguished all prolactinomas from stalk effect in this study, including a validation cohort specifically chosen for potential ambiguity. To our knowledge, this study is the first formal volumetric analysis of prolactin secretion in pituitary adenomas, and our results suggest that the measurement of prolactin/mm³ is a valuable tool to better characterize challenging cases of primary tumoral secretion versus secondary hyperprolactinemia due to stalk effect.     

β-Carotene enhances the expression of inflammation-related genes and histone H3 K9 acetylation,K4 dimethylation,and K36 trimethylation around these genes in juvenile macrophage-like THP-1 cells

β-Carotene is converted into vitamin A in the body and can remove reactive oxygen species. However, it is still unclear whether β-carotene alters the expression levels of inflammation-related genes in macrophages and how this is regulated. In the present study, we investigated whether the administration of β-carotene under hyperglycemic conditions altered the expression level of inflammation-related genes and whether any observed differences were associated with changes in histone modifications in juvenile macrophage-like THP-1 cells. THP-1 cells (from a human monocytic leukemia cell line) were cultured in low glucose (5 mM), high glucose (25 mM), or high glucose (25 mM) + β-carotene (5 μM) media for 1 day, and mRNA expression levels of genes related to oxidative stress and inflammation, and histone modifications were determined by mRNA microarray and qRT-PCR analyses, and chromatin immunoprecipitation assays, respectively. The expression of inflammation-related genes, such as IL31RA, CD38, and NCF1B, and inflammation-associated signaling pathway genes, such as ITGAL, PRAM1, and CSF3R, were upregulated by β-carotene under high-glucose conditions. Under these conditions, histone H3 lysine 4 (K4) demethylation, H3K36 trimethylation, and H3K9 acetylation around the CD38, NCF1B, and ITGAL genes were higher in β-carotene-treated cells than in untreated cells. Treatment of juvenile macrophage-like THP-1 cells with β-carotene under these high glucose conditions induced the expression of inflammation-related genes, K9 acetylation, and K4 di- and K36 trimethylation of histone H3 around these genes.