Background: Clinical and basic investigations have indicated a significant association between circulating growth differentiation factor 15 (GDF15) and cardiovascular disease; however, the relationship between GDF15 and lower extremity atherosclerotic disease (LEAD) has been less studied. The present study aimed to explore the association between GDF15 and LEAD in Chinese patients with type 2 diabetes mellitus (T2DM). Considering that obesity is an important factor associated with circulating GDF15 levels, whether the relationship between serum GDF15 levels and LEAD is affected by body mass index (BMI) was also analysed.Methods: A total of 376 hospitalized T2DM patients were enrolled (161 with LEAD and 215 without LEAD). A sandwich enzyme-linked immunosorbent assay was used to detect the serum GDF15 levels. The femoral intima-media thickness (F-IMT) and LEAD were assessed by ultrasonography.Results: Patients with LEAD had significantly higher serum GDF15 levels than those without LEAD, regardless of whether their BMI was < 25 kg/m 2 or ≥ 25 kg/m 2 (both P < 0.05). Serum GDF15 levels were independently positively related to the F-IMT (standardized β = 0.162, P = 0.002). After adjusting for confounding factors, per 1-standard deviation (SD) increase in the serum GDF15 levels was significantly related to an approximately 1.4-fold increased risk of LEAD in the total population (P < 0.05). Regardless of whether the BMI was < 25 kg/m 2 or ≥ 25 kg/m 2 , this association remained significant, with approximately 1.6-and 1.4-fold increased risks of LEAD, respectively (both P < 0.05). Conclusions: High serum GDF15 levels were significantly correlated with an increased risk of LEAD in T2DM patients, and this relationship was independent of BMI.
Here, we studied the metabolic function of LAMTOR1 from macrophages using LAMTOR1 macrophage-specific knockout (MKO) mice. LAMTOR1 MKO mice showed resistance to high-fat diet (HFD)-induced obesity, lipid steatosis, and glucose metabolic disorders, with elevated levels of pro-inflammatory cytokines. The energy expenditure, oxygen consumption, and CO2 production increased significantly in HFD-fed MKO vs. wild-type (WT) mice. HE and immunohistochemistry staining showed a remarkable CD68+ Kupffer cell accumulation in the liver. Additionally, flow cytometry revealed that the proportion of macrophages and monocytes increased significantly in the liver of MKO mice. Of note, these macrophages were probably derived from the bone marrow since the proportion of CD11b+ cells as well as the proliferative activity was also increased in the context of femoral bone marrow cells. In addition, the Kupffer cells of both WT and KO mice were double-positive for the M1 (CD86) and M2 (CD206) markers. However, the expression of both M1 and M2 macrophage-related genes was increased in the liver of HFD-fed KO mice. Murine primary hepatocytes and Kupffer cells were further isolated and incubated with oleic acid for 24 h. The glucose output of primary hepatocytes from MKO mice was not affected. However, decreased lipid tolerance was observed in LAMTOR1-deficient Kupffer cells. Overall, our results suggest that LAMTOR1 deficiency in macrophages prevents obesity and metabolic disorders via the accumulation of Kupffer cells in the liver and the consequent hyper-inflammation and increased energy expenditure. Therefore, our results provide a new perspective for macrophage-derived LAMTOR1 in the context of systemic metabolism.
Background: Recent studies noted that circulating growth differentiation factor 15 (GDF15) were closely related to metabolic states. The study aimed to explore the changes of GDF15 levels and their influencing factors after 4 weeks of lifestyle intervention (LI) or LI combined with breakfast meal replacement (LI+MR) in newly diagnosed type 2 diabetes patients. Methods: A total of 84 patients with available serum samples at both baseline and Week 4 were enrolled in this biomarker substudy. All subjects underwent a 2-hour 75g oral glucose tolerance test at baseline and Week 4. Serum GDF15 levels were determined by a sandwich enzyme-linked immunosorbent assay. Results: After 4-weeks of LI, GDF15 levels overall significantly decreased compared with baseline (P<0.05). ∆GDF15 levels were significantly and negatively associated with baseline GDF15 levels (r=–0.450, P<0.001). The optimal cut-off point of baseline GDF15 levels for predicting a GDF15 decrease after 4-weeks of LI was 904.57 pg/ml, with an area under curve of 0.699. Based on the cut-off point of 900 pg/ml, patients with baseline GDF15 ≥900 pg/ml had significantly decreased GDF15 levels after LI, while those <900 pg/ml had no significant changes. Regression models showed that baseline GDF15 level was an independent positive factor for the improvement of fasting plasma glucose and homeostasis model assessment for insulin resistance only in patients with baseline GDF15 levels ≥900 pg/ml. Conclusions: LI led to significantly decreased GDF15 levels among patients with newly diagnosed type 2 diabetes and its effect was more significant among patients with baseline GDF15 levels ≥900 pg/ml.Trial registration: ClinicalTrials.gov, NCT02248714. Registered 25 September 2014 - Retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT02248714?term=NCT02248714&draw=2&rank=1
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