Neurotensin Gene rs2234762 C>G Variant Associates with Reduced Circulating Pro-NT Levels and Predicts Lower Insulin Resistance in Overweight/Obese Children

Circulating Proneurotensin Levels Predict Impaired Bone Mineralisation in Postmenopausal Women With Type 2 Diabetes Mellitus

CONTEXT

The mechanisms underlying bone fragility and increased fracture risk observed in individuals with type 2 diabetes (T2D) are not yet fully elucidated. Previous research has suggested a role for neuropeptides in regulating bone metabolism; however, the contribution of the neuropeptide Neurotensin (NT), which is thoroughly implicated in T2D and cardiovascular disease, has not been investigated in this context.

OBJECTIVE

To study the relationship between circulating levels of the NT precursor proneurotensin (proNT) and bone mineralisation in T2D women.

MATERIALS AND METHODS

This is a cross-sectional investigation with a longitudinal prospective phase, involving 126 women with T2D who underwent bone density scans and had proNT levels measured. Biomarkers of bone metabolism and inflammation were also assessed. Data on bone mineral density (BMD) after 12 months were available for 49 patients.

MAIN OUTCOME MEASURE

Plasma proNT levels in relation to BMD.

RESULTS

32% of the participants had osteopenia/osteoporosis and exhibited higher proNT than those with normal BMD (200.8 ± 113.7 vs. 161.6 ± 108.8 pg/mL; p = 0.013). ProNT inversely correlated with femur BMD and T-score (p < 0.01) and was associated with degraded bone architecture (TBS, p = 0.02), and higher OPN, P1NP, TNF-α and IL-1β levels. Baseline proNT correlated with further BMD reduction at the 12-month follow-up, independently of potential confounders (p = 0.02).

CONCLUSIONS

In women with T2D, greater proNT levels are associated with impaired bone mineralisation and predict mineral density decline overtime. ProNT could potentially serve as a diagnostic tool for identifying patients at higher risk of osteopenia/osteoporosis, suggesting a significant connection between this neuropeptide and bone metabolism in diabetes.

Roles of Matrix Metalloproteinases and Their Natural Inhibitors in Metabolism: Insights into Health and Disease

Matrix metalloproteinases (MMPs) are a family of zinc-activated peptidases that can be classified into six major classes, including gelatinases, collagenases, stromelysins, matrilysins, membrane type metalloproteinases, and other unclassified MMPs. The activity of MMPs is regulated by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). MMPs are involved in a wide range of biological processes, both in normal physiological conditions and pathological states. While some of these functions occur during development, others occur in postnatal life. Although the roles of several MMPs have been extensively studied in cancer and inflammation, their function in metabolism and metabolic diseases have only recently begun to be uncovered, particularly over the last two decades. This review aims to summarize the current knowledge regarding the metabolic roles of metalloproteinases in physiology, with a strong emphasis on adipose tissue homeostasis, and to highlight the consequences of impaired or exacerbated MMP actions in the development of metabolic disorders such as obesity, fatty liver disease, and type 2 diabetes.