In vitro and in vivo effects of zoledronic acid on senescence and senescence-associated secretory phenotype markers

In addition to reducing fracture risk, zoledronic acid has been found in some studies to decrease mortality in humans and extend lifespan and healthspan in animals. Because senescent cells accumulate with aging and contribute to multiple co-morbidities, the non-skeletal actions of zoledronic acid could be due to senolytic (killing of senescent cells) or senomorphic (inhibition of the secretion of the senescence-associated secretory phenotype [SASP]) actions. To test this, we first performed in vitro senescence assays using human lung fibroblasts and DNA repair-deficient mouse embryonic fibroblasts, which demonstrated that zoledronic acid killed senescent cells with minimal effects on non-senescent cells. Next, in aged mice treated with zoledronic acid or vehicle for 8 weeks, zoledronic acid significantly reduced circulating SASP factors, including CCL7, IL-1β, TNFRSF1A, and TGFβ1 and improved grip strength. Analysis of publicly available RNAseq data from CD115+ (CSF1R/c-fms+) pre-osteoclastic cells isolated from mice treated with zoledronic acid demonstrated a significant downregulation of senescence/SASP genes (SenMayo). To establish that these cells are potential senolytic/senomorphic targets of zoledronic acid, we used single cell proteomic analysis (cytometry by time of flight [CyTOF]) and demonstrated that zoledronic acid significantly reduced the number of pre-osteoclastic (CD115+/CD3e-/Ly6G-/CD45R-) cells and decreased protein levels of p16, p21, and SASP markers in these cells without affecting other immune cell populations. Collectively, our findings demonstrate that zoledronic acid has senolytic effects in vitro and modulates senescence/SASP biomarkers in vivo. These data point to the need for additional studies testing zoledronic acid and/or other bisphosphonate derivatives for senotherapeutic efficacy.

In vitro and in vivo effects of zoledronate on senescence and senescence-associated secretory phenotype markers

In addition to reducing fracture risk, zoledronate has been found in some studies to decrease mortality in humans and extend lifespan and healthspan in animals. Because senescent cells accumulate with aging and contribute to multiple co-morbidities, the non-skeletal actions of zoledronate could be due to senolytic (killing of senescent cells) or senomorphic (inhibition of the secretion of the senescence-associated secretory phenotype [SASP]) actions. To test this, we first performed in vitro senescence assays using human lung fibroblasts and DNA repair-deficient mouse embryonic fibroblasts, which demonstrated that zoledronate killed senescent cells with minimal effects on non-senescent cells. Next, in aged mice treated with zoledronate or vehicle for 8 weeks, zoledronate significantly reduced circulating SASP factors, including CCL7, IL-1β, TNFRSF1A, and TGFβ1 and improved grip strength. Analysis of publicly available RNAseq data from CD115+ (CSF1R/c-fms+) pre-osteoclastic cells isolated from mice treated with zoledronate demonstrated a significant downregulation of senescence/SASP genes (SenMayo). To establish that these cells are potential senolytic/senomorphic targets of zoledronate, we used single cell proteomic analysis (cytometry by time of flight [CyTOF]) and demonstrated that zoledronate significantly reduced the number of pre-osteoclastic (CD115+/CD3e-/Ly6G-/CD45R-) cells and decreased protein levels of p16, p21, and SASP markers in these cells without affecting other immune cell populations. Collectively, our findings demonstrate that zoledronate has senolytic effects in vitro and modulates senescence/SASP biomarkers in vivo . These data point to the need for additional studies testing zoledronate and/or other bisphosphonate derivatives for senotherapeutic efficacy.

Update on the pathogenesis and treatment of skeletal fragility in type 2 diabetes mellitus

Fracture risk is increased in patients with type 2 diabetes mellitus (T2DM). In addition, these patients sustain fractures despite having higher levels of areal bone mineral density, as measured by dual-energy X-ray absorptiometry, than individuals without T2DM. Thus, additional factors such as alterations in bone quality could have important roles in mediating skeletal fragility in patients with T2DM. Although the pathogenesis of increased fracture risk in T2DM is multifactorial, impairments in bone material properties and increases in cortical porosity have emerged as two key skeletal abnormalities that contribute to skeletal fragility in patients with T2DM. In addition, indices of bone formation are uniformly reduced in patients with T2DM, with evidence from mouse studies published over the past few years linking this abnormality to accelerated skeletal ageing, specifically cellular senescence. In this Review, we highlight the latest advances in our understanding of the mechanisms of skeletal fragility in patients with T2DM and suggest potential novel therapeutic approaches to address this problem.

Midterm Outcome of Laparoscopic Sleeve Gastrectomy in Asians: a Systematic Review and Meta-analysis

BACKGROUND

Laparoscopic sleeve gastrectomy (LSG) is a commonly performed bariatric surgery. Studies have suggested that LSG can provide effective and sustainable weight loss although most of them were conducted in Western populations. Our aim was to characterize the midterm outcome of LSG in Asians with obesity.

METHODS

MEDLINE and EMBASE were searched through August 2019 for studies that reported % total body weight loss (TBWL) and/or % excess weight loss (EWL) at 3 and/or 5 years among adult Asians with obesity who underwent LSG. Data on complications and surgical revision rate were also extracted. The pooled effect size and 95% confidence interval (CI) were calculated using a random effects model.

RESULTS

A total of 19 studies involving 6235 patients were included. The pooled mean %EWLs were 72.6% (95% CI 67.2-78.0, I² = 97%); 67.1% (95% CI 61.7-72.6, I² = 95%); and 59.1% (95% CI 48.8-69.4, I² = 94%) at 1, 3, and 5 years, respectively. The pooled mean %TBWLs were 32.1%, 29.0%, and 25.5% at 1, 3, and 5 years, respectively. The pooled rates of revision due to gastroesophageal reflux disease and weight regain were 1.9% and 2.5%, respectively.

CONCLUSIONS

Our meta-analysis suggests that LSG is an effective procedure for weight reduction that offers durable response for up to 5 years among Asians with obesity. The longer-term data is needed.

Determinants of Bone Material Strength and Cortical Porosity in Patients with Type 2 Diabetes Mellitus

CONTEXT

Reduced bone material strength index (BMSi) and increased cortical porosity (CtPo) have emerged as potentially contributing to fracture risk in type 2 diabetes mellitus (T2DM) patients.

OBJECTIVE

To determine whether BMSi or CtPo are related to other diabetic complications.

DESIGN

Cross-sectional observational study.

SETTING

Subjects recruited from a random sample of southeast Minnesota residents.

PARTICIPANTS

A total of 171 T2DM patients (mean age, 68.8 years) and 108 age-matched nondiabetic controls (mean age, 67.3 years).

MAIN MEASURES

Bone material strength index was measured using microindentation, skin advanced glycation end-products (AGEs) measured using autofluorescence, high-resolution peripheral quantitative computed tomography at the distal radius and tibia, assessment of diabetic microvascular complications including urine microalbuminuria, retinopathy, neuropathy, and vascular disease (ankle brachial index and transcutaneous oxygen tension [TcPO2]). All analyses were adjusted for age, sex, and body mass index.

RESULTS

Skin AGEs were negatively correlated with the BMSi in both T2DM (r = -0.30, P < 0.001) and control (r = -0.23, P = 0.020) subjects. In relating diabetic complications to CtPo, we found that T2DM patients with clinically significant peripheral vascular disease (TcPO2 ≤ 40 mm Hg) had higher (+21.0%, P = 0.031) CtPo at the distal tibia as compared to controls; in these subjects, CtPo was negatively correlated with TcPO2 at both the distal tibia (r = -0.39, P = 0.041) and radius (r = -0.41, P = 0.029).

CONCLUSIONS

Our findings demonstrate that bone material properties are related to AGE accumulation regardless of diabetes status, while CtPo in T2DM patients is linked to TcPO2, a measure of microvascular blood flow.

MON-912 Undiagnosed Chronic Eczema as a Presentation of Glucagonoma in MEN 1 Syndrome

Background: Glucagonomas are pancreatic tumors arising from the islets cell of Langerhans that over secrete glucagon. Necrolytic migratory erythema (NME) is an important feature for the recognition of glucagonomas. Glucagonomas occurring in MEN1 is infrequent and seen in less than 3% of all glucagonomas.

Clinical Case: A 51-year-old male presented to the clinic multiple visits for rash affecting the legs and genital area of two months. His medical history include type 2 DM and HT. The rash was attributed to subacute eczema and treated with topical steroids but showed no improvement. The skin eruption initially appeared on lower extremities progressed to trunk, and face. The skin lesions were associated with weight loss and stomatitis. On physical examination, skin showed ill-defined erythematous plaque exhibiting annular pattern, scale, and erosion on all extremities and perioral area. When the skin lesions healed, the new cutaneous eruptions occurred. Laboratory testing revealed plasma glucose of 185 mg/dL. The skin biopsy reported vacuolated keratinocytes in the epidermis with eosinophil cytoplasm, compatible with NME leading to further workup for pancreatic tumor. CT abdomen revealed tumor mass 9.6x6 cm at the pancreatic tail and multiple nodules in the liver. Somatostatin receptor scintigraphy showed an area of increased radiotracer uptake at the tail of the pancreas and multiple liver nodules corresponding to the previous CT scan. Serum glucagon was 923 pg/mL, confirming the diagnosis for glucagonoma. The patient was treated with distal pancreatectomy, and enucleation of liver metastases. Histopathological reported grade 2 well-differentiated NET. During the admission, the patient was found to have a parathyroid level of 79.3 pg/mL and increased uptake in the left and right lower regions of the thyroid gland from parathyroid MIBI scan, indicating hyperfunctioning parathyroid glands. All pituitary hormones were within normal ranges and no pituitary tumor was detected by the MRI brain. BMD showed osteoporosis at the lumbar spine and left femoral neck. The patient was referred to general surgery for subtotal parathyroidectomy. Pathological of resected parathyroid glands reported parathyroid hyperplasia. Postoperative PTH level and calcium were returned to normal range. Genetic testing focused on MEN1 gene, and the mutation was identified. After four months follow up plasma glucagon decreased to 425 pg/dL, patient had complete resolution of the cutaneous lesions.

Conclusion: Glucagonomas are a rare pancreatic tumors and often difficult to recognize. Chronic eczema may misdiagnose for NME and delay diagnosis. NME can be challenging for physicians to recognize NME which is an important key to diagnose glucagonoma. Even though MEN1 association with glucagonoma is infrequent, awareness of such is important to allow appropriate testing for MEN1 in patients with glucagonoma.

SUN-381 Cortical Porosity Is Associated with Peripheral Small Vessel Disease in Adult Patients with Type 2 Diabetes

Patients with Type 2 Diabetes (T2D) are at higher fracture risk despite having relatively normal or even increased BMD by DXA. Increased cortical porosity has emerged as a potential factor contributing to fragility fractures in T2D. However, there is conflicting evidence whether T2D patients have increased cortical porosity. We hypothesized that microvascular complications have an important role in cortical porosity. Thus, we performed high-resolution peripheral quantitative computed tomography imaging at the distal radius and tibia to evaluate bone microarchitecture in men with T2DM age ≥ 50 yrs or postmenopausal women with T2DM and nondiabetic controls. Comprehensive diabetic complications were assessed in all patients including urine microalbuminuria, retinopathy, neuropathy (touch, temperature, and vibration sensation), ankle brachial index (ABI) and transcutaneous oxygen tension (TcPO2). Percent differences between groups were obtained from linear regression models adjusting for age, BMI, and sex. Relationships between variables were assessed using adjusted Spearman correlations. A total of 164 T2D patients (mean age 68.9 ±7.8 yrs.; 56.7% men; HbA1C=7.7 ±0.9%; mean diabetes duration 15.2 yrs.) and 107 nondiabetic controls (mean age 67.3±8.8 yrs.; 42.1% men; HbA1C =5.4 ±0.3%) were recruited to the study. Overall, there was a trend for increased cortical porosity at the distal tibia in the T2D group (+12.2%; p=0.063) compared with nondiabetic controls. Of note, TcPO2 was negatively correlated with cortical porosity at the distal radius (r= -0.17; p= 0.039) and distal tibia (r= -0.15; p= 0.073). In particular, the Low TcPO2 (≤40 mmHg) group (n=29) had greater cortical porosity at the distal tibia (+19.6 %; p=0.037) compared with the High TcPO2 (>40 mmHg) group (n=133). In addition, the low TcPO2 group had a significant increase in cortical porosity in the distal tibia (+24.8% p=0.020) compared with nondiabetic controls. In conclusion, this is the first evidence in humans indicating that TcPO2, a measure of microvascular blood flow, is linked to cortical porosity in the distal radius and tibia in T2D patients. Our findings may explain the conflicting findings regarding cortical porosity in T2D because only T2D patients with impaired microvascular blood flow have increased cortical porosity. Collectively, our data indicate that cortical porosity is a microvascular complication of longstanding T2D.

SUN-LB68 Advanced Glycation Endproducts Are Associated With Worse Bone Material Strength in Older Adults With and Without Type 2 Diabetes

Patients with Type 2 Diabetes (T2D) are at increased fracture risk despite having relatively normal or even increased BMD by DXA. The critical aspect of bone quality deterioration in T2D patients could explain this clinically important discrepancy. Material composition is a component of bone quality that has emerged as a potential factor contributing to fragility fractures in T2D patients. However, there is sparse evidence regarding whether T2D patients have decreased bone material properties compared with non-diabetic controls. We hypothesized that increased production of advanced glycation endproducts (AGEs) has an important role in reducing bone material strength in patients with and without diabetes. Thus, we used the OsteoProbe®, a bone microindentation device that provides an index of cortical bone material properties (Bone Material Strength index – BMSi) in men with T2D age ≥ 50 yrs or postmenopausal women with T2D and nondiabetic controls. We also utilized a non-invasive measure of skin AGEs (AGE Reader®) to evaluate AGEs accumulation through skin autofluorescence. Linear regression models were used to assess group differences with and without adjusting for age, Body Mass Index (BMI), and sex. Relationships between variables were assessed using adjusted Pearson correlations. A total of 152 T2D patients (mean age 68.5 ±7.6 yrs.; 59.2% men; HbA1C=7.7 ±1.0%; mean diabetes duration 15.5 yrs.) and 105 non-diabetic controls (mean age 67.2±8.8 yrs.; 41.0% men; HbA1C =5.4 ±0.3%) were recruited to the study. Overall, there was no difference in BMSi between T2DM and control subjects: unadjusted (p= 0.636); adjusted (p= 0.695). However, skin AGEs were negatively correlated with BMSi (r= -0.23, p &lt;0.001). In subgroup analyses, skin AGEs were also negatively associated with BMSi in both T2DM (r= -0.23, p=0.004) and control (r= -0.21, p=0.033) subjects. In conclusion, these findings demonstrate that a higher burden of AGEs is associated with worse bone quality. Our findings may explain the conflicting findings regarding reductions in BMSi in T2D because only T2D patients with a high level of AGEs accumulation have impaired BMSi. Moreover, the association of skin AGEs with BMSi in non-diabetic subjects emphasizes the important role of AGEs in decreasing bone quality and potentially contributing to fracture risk. Collectively, our data indicate that non-invasive skin AGEs measurement could be used as a tool to evaluate bone quality in patients with T2D as well as in the non-diabetic population.