Long-term effects of canagliflozin treatment on the skeleton of aged UM-HET3 mice

Anti-aging interventions in geriatric mice: insights into the timing of treatment, benefits, and limitations

Studies aimed at preventing age-associated diseases are fundamental in addressing the challenges posed by an aging population. However, biomedical and technological advancements have now reached a stage where it appears increasingly possible to repair the damage caused by severe pathologies and reverse the functional decline that accompanies aging. This perspective highlights the significance of using aging models, specifically non-transgenic geriatric mice (aged over 24 months), to study interventions aimed at reversing or ameliorating age-related pathologies. While most research typically utilizes young, adult, and mid-aged mice to investigate aging mechanisms and develop preventive strategies, geriatric models provide unique insights into the efficacy and safety of treatments in conditions that mimic the complexities of multiple concurrent diseases or syndromes. This manuscript highlights the importance of considering timing responses in aging interventions, illustrated by recent findings such as those involving canagliflozin. These studies reveal that the timing of intervention can significantly influence the outcomes, highlighting aspects often overlooked. Practical challenges and resource demands associated with geriatric mouse studies including concerns related to animal husbandry and aging phenotypes are also discussed. This perspective aims to foster a deeper understanding of the potential benefits and limitations of geriatric mice models in geroscience research and emphasizes the need for continued innovation in this field to meet the critical need to develop effective treatments for age-related diseases.

Deletion of absent in melanoma-2 (AIM2) drives bone marrow adipogenesis and impairs bone microarchitecture

Absent in melanoma (AIM) 2, a gene induced by interferon, acts as a cytosolic sensor for double-stranded (ds) DNA. It forms the AIM2 inflammasome, producing interleukin (IL)-1β and IL-18. Our previous study demonstrated that mice lacking AIM2 exhibit spontaneous obesity, insulin resistance, and inflammation in adipose tissue. In this study, we aimed to explore the impact of AIM2 gene deletion on the bone marrow microenvironment and bone morphology in adult and aged mice. Utilizing micro-computed tomography (micro-CT), we discovered that female mice lacking AIM2 showed an increase in the total cross-sectional area at 5 months of age, accompanied by an increase in cortical thickness in the mid-diaphysis of the femur at both 5 and 15 months of age. At 15 months, the cortical bone mineral density (BMD) significantly decreased in AIM2 null females compared to wildtype (WT) mice. Trabecular bone volume and BMD at the distal metaphysis of the femur and the lumbar vertebra-4 were also significantly decreased in AIM2 null females. Histological examination of femurs from aged mice demonstrated increased bone marrow adiposity in AIM2 null mice, accompanied by a significant increase in CD45 - /CD31 - /Sca1 + /Pdgfa + adipogenic progenitor cells and a decrease in the ratio of CD45 - /CD31 - /Sca1 - /Pdgfa + osteogenic progenitor cells, as determined by flow cytometry of bone marrow cells. RNAseq analysis of the bone marrow revealed a significant increase in interferon-stimulated genes with Ifi202b as the top-upregulated gene in AIM2 null mice. Our findings suggest that AIM2 deficiency affects bone health by promoting adipogenesis in the bone marrow and inducing a pro-inflammatory environment, thereby contributing to decreased bone mineral density.

Concomitant use of sodium-glucose co-transporter 2 inhibitors and metformin and the risk of osteomyelitis reporting: a disproportionality analysis based on FAERS database

BACKGROUND

Recent clinical case reports have generated controversy concerning the adverse events (AEs) of amputation linked to sodium-glucose co-transporter 2 inhibitors (SGLT2i). We assessed the risk of osteomyelitis AE reporting linked to SGLT2i or SGLT2i-metformin co-medication.

RESEARCH DESIGN AND METHODS

Investigated the FDA Adverse Event Reporting System for osteomyelitis-related AEs associated with SGLT2i or SGLT2i-metformin co-medication from 2013q2 to 2023q1. Comprehensive disproportionality analysis and Bayesian confidence propagation methods were used to detect safe signals. The additive interaction model, multiplicative interaction model, and Ω shrinkage measure were employed to explore the latent interactions between SGLT2i and metformin. A Venn diagram was utilized to estimate the coincidence of related osteomyelitis and amputation.

RESULTS

Among 2,569 SGLT2i-associated osteomyelitis reports, we identified 2,509 related to canagliflozin (ROR 104.47; PRR 99.70, χ2 = 214840.90; EBGM05 = 84.38; IC025 = 4.78) and 103 related to the SGLT2i-metformin compound. Drug-drug interaction detection revealed a negative correlation RERI = -21.73, eβ3 = 0.699, Ω025=-1.370). The coincidence of osteomyelitis and amputation linked to SGLT2i (2,672 vs. 3,548) was 2,150(80%) by Venn diagram.

CONCLUSIONS

This study showed an increased risk of SGLT2i-associated osteomyelitis, focusing on canagliflozin, and presented a potential association between amputation and osteomyelitis, providing a reference for the clinical practice of diabetes with SGLT2i medication.

In nondiabetic C57BL/6J mice, canagliflozin affects the skeleton in a sex- and age-dependent manner

Canagliflozin (CANA) is a sodium glucose cotransporter-2 inhibitor that reduces blood glucose levels. Sodium glucose cotransporter-2 is primarily expressed in the kidney, but not in any bone cells, therefore effects on the skeleton are likely to be non-cell autonomous. Originally developed to treat type II diabetes, CANA use has expanded to treat cardiovascular and renovascular disease. Clinical trials examining CANA in diabetic patients have produced contradictory reports on fracture risk, but there are limited data of CANA in nondiabetic conditions. In nondiabetic preclinical models, short-term treatment with CANA negatively affected trabecular bone whereas long-term treatment reduced cortical bone mineralization in male but not female mice. To investigate the skeletal effects of an intermediate period of CANA treatment, we treated male and female C57BL/6 J mice with CANA (180 ppm) for 6 months. Age at treatment initiation was also evaluated, with cohorts starting CANA prior to skeletal maturity (3-months-old) or in adulthood (6-months-old). Longitudinal assessments of bone mineral density revealed early benefits of CANA treatment in female mice. At euthanasia, both trabecular and cortical bone morphology were improved by CANA treatment in males and females. Bone formation was reduced at the endosteal surface. CANA decreased osteoblast number in male mice and bone marrow adiposity in females. Overall, more skeletal benefits were recorded in CANA-treated females than males. Urinary calcium output increased with CANA treatment, but parathyroid hormone was not changed. Despite reduced fasting blood glucose, body composition and whole-body metabolism were minimally changed by CANA treatment. For all outcome measures, limited differences were recorded based on age at treatment initiation. This study demonstrated that in nondiabetic C57BL/6 J mice, an intermediate period of CANA treatment improved bone morphology, but reduced osteoblast and bone marrow adipocyte number as well as serum procollagen type 1 N-terminal pro-peptide in a sex-specific manner.

The impact of inactivation of the GH/IGF axis during aging on healthspan

Several mouse lines with congenital growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis disruption have shown improved health and extended lifespan. The current study investigated how inactivating this axis, specifically during aging, impacts the healthspan. We used a tamoxifen-inducible global GH receptor (GHR) knockout mouse model starting at 12 months and followed the mice until 24 months of age (iGHRKO12-24 mice). We found sex- and tissue-specific effects, with some being pro-aging and others anti-aging. Measuring an array of cytokines in serum revealed that inactivation of the GH/IGF-1 axis at 12 months did not affect systemic inflammation during aging. On the other hand, hypothalamic inflammation was significantly reduced in iGHRKO12-24 mice, evidenced by GFAP+ (glial fibrillary acidic protein, a marker of astrocytes) and Iba-1+ (a marker for microglia). Liver RNAseq analysis indicated feminization of the male transcriptome, with significant changes in the expression of monooxygenase, sulfotransferase, and solute-carrier-transporter gene clusters. Finally, we found impaired bone morphology, more pronounced in male iGHRKO12-24 mice and correlated with GH/IGF-1 inactivation onset age. We conclude that inhibiting the GH/IGF-1 axis during aging only partially preserves the beneficial healthspan effects observed with congenital GH deficiency.

Canagliflozin protects against hyperglycemia-induced cerebrovascular injury by preventing blood-brain barrier (BBB) disruption via AMPK/Sp1/adenosine A2A receptor

Diabetes mellitus causes brain microvascular endothelial cell (MEC) damage, inducing dysfunctional angiogenic response and disruption of the blood-brain barrier (BBB). Canagliflozin is a revolutionary hypoglycemic drug that exerts neurologic and/or vascular-protective effects beyond glycemic control; however, its underlying mechanism remains unclear. In the present study, we hypothesize that canagliflozin ameliorates BBB permeability by preventing diabetes-induced brain MEC damage. Mice with high-fat diet/streptozotocin-induced diabetes received canagliflozin for 8 weeks. We assessed vascular integrity by measuring cerebrovascular neovascularization indices. The expression of specificity protein 1 (Sp1), as well as tight junction proteins (TJs), phosphorylated AMP-activated protein kinase (p-AMPK), and adenosine A2A receptors was examined. Mouse brain MECs were grown in high glucose (30 mM) to mimic diabetic conditions. They were treated with/without canagliflozin and assessed for migration and angiogenic ability. We also performed validation studies using AMPK activator (AICAR), inhibitor (Compound C), Sp1 small interfering RNA (siRNA), and adenosine A2A receptor siRNA. We observed that cerebral pathological neovascularization indices were significantly normalized in mice treated with canagliflozin. Increased Sp1 and adenosine A2A receptor expression and decreased p-AMPK and TJ expression were observed under diabetic conditions. Canagliflozin or AICAR treatment alleviated these changes. However, this alleviation effect of canagliflozin was diminished again after Compound C treatment. Either Sp1 siRNA or adenosine A2A receptor siRNA could increase the expression of TJs. Luciferase reporter assay confirmed that Sp1 could bind to the adenosine A2A receptor gene promoter. Our study identifies the AMPK/Sp1/adenosine A2A receptor pathway as a treatment target for diabetes-induced cerebrovascular injury.

Deletion of absent in melanoma (AIM) 2 gene alters bone morphology

Absent in Melanoma (AIM) 2 is a gene that is induced by interferon and acts as a cytosolic sensor for double-stranded (ds) DNA. It forms the AIM2 inflammasome, leading to the production of interleukin (IL)-1β and IL-18. Our previous research demonstrated that mice lacking AIM2 exhibit spontaneous obesity, insulin resistance, and inflammation in adipose tissue. In this study, we aimed to explore the impact of AIM2 gene deletion on bone structure in adult and aged mice. Utilizing micro-computed tomography (micro-CT), we discovered that female mice lacking AIM2 showed an increase in the total cross-sectional area at 5 months of age, accompanied by an increase in cortical thickness in the mid-diaphysis of the femur at both 5 and 15 months of age. At 15 months of age, the cortical bone mineral density (BMD) significantly decreased in AIM2 null females compared to wild-type (WT) mice. In AIM2 null mice, both trabecular bone volume and BMD at the distal metaphysis of the femur significantly decreased at 5 and 15 months of age. Similarly, micro-CT analysis of the L4 vertebra revealed significant decreases in trabecular bone volume and BMD in aged AIM2 null females compared to WT mice. Histological examination of femurs from aged mice demonstrated increased bone marrow adiposity in AIM2 null mice, accompanied by a significant increase in CD45-/CD31-/Sca1+/Pdgfa+ adipose progenitor cells, and a decrease in the ratio of CD31-/CD31+ osteogenic progenitor cells, as determined by flow cytometry of bone marrow cells. Our findings suggest that AIM2 deficiency affects bone health by promoting adipogenesis in bone marrow cells and inducing a pro-inflammatory environment, potentially contributing to the decreased bone mineral density.

Geroprotector drugs and exercise: friends or foes on healthy longevity?

Physical activity and several pharmacological approaches individually combat age-associated conditions and extend healthy longevity in model systems. It is tantalizing to extrapolate that combining geroprotector drugs with exercise could extend healthy longevity beyond any individual treatment. However, the current dogma suggests that taking leading geroprotector drugs on the same day as exercise may limit several health benefits. Here, we review leading candidate geroprotector drugs and their interactions with exercise and highlight salient gaps in knowledge that need to be addressed to identify if geroprotector drugs can have a harmonious relationship with exercise.