Blood Levels of the SMOC1 Hepatokine Are Not Causally Linked with Type 2 Diabetes: A Bidirectional Mendelian Randomization Study

Hepatokines are liver-derived proteins that may influence metabolic pathways such as insulin sensitivity. Recently, Sparc-related modular calcium-binding protein 1 (SMOC1) was identified as glucose-responsive hepatokine that is dysregulated in the setting of non-alcoholic fatty liver disease (NAFLD). While SMOC1 may influence glucose-insulin homeostasis in rodents, it is unknown if SMOC1 is influenced by NAFLD in humans. It is also unknown if SMOC1 is causally associated with metabolic and disease traits in humans. Therefore, we aimed to determine the effect of NAFLD on SMOC1 gene expression in the liver and aimed to explore the potential causal associations of SMOC1 levels with NAFLD, T2D, and glycemic traits in humans. Using an RNA sequencing dataset from a cohort of 216 patients with NAFLD, we assessed SMOC1 expression levels across the NAFLD spectrum. We performed a series of bidirectional inverse-variance weighted Mendelian randomization (MR) analyses on blood SMOC1 levels using two sources of genome-wide association studies (GWAS) (Fenland study, n = 10,708 and INTERVAL study, n = 3301). We utilized GWAS summary statistics for NAFLD in 8434 cases and 770,180 controls, as well as publicly available GWAS for type 2 diabetes (T2D), body mass index (BMI), waist-to-hip ratio (WHR), fasting blood insulin (FBI), fasting blood glucose (FBG), homeostatic Model Assessment of Insulin Resistance (HOMA-B and HOMA-IR), and hemoglobin A1c (HbA1C). We found that SMOC1 expression showed no significant differences across NAFLD stages. We also identified that the top single-nucleotide polymorphism associated with blood SMOC1 levels, was associated with SMOC1 gene expression in the liver, but not in other tissues. Using MR, we did not find any evidence that genetically predicted NAFLD, T2D, and glycemic traits influenced SMOC1 levels. We also did not find evidence that blood SMOC1 levels were causally associated with T2D, NAFLD, and glycemic traits. In conclusion, the hepatokine SMOC1 does not appear to be modulated by the presence of NAFLD and may not regulate glucose-insulin homeostasis in humans. Results of this study suggest that blood factors regulating metabolism in rodents may not always translate to human biology.

Engineered human brown adipocyte microtissues improved glucose and insulin homeostasis in high fat diet-induced obese and diabetic mice

A large population of people is affected by obesity (OB) and its associated type 2 diabetes mellitus(T2DM). There are currently no safe and long-lasting anti-OB/T2DM therapies. Clinical data and preclinical transplantation studies show that transplanting metabolically active brown adipose tissue (BAT) is a promising approach to prevent and treat OB and its associated metabolic and cardiovascular diseases. However, most transplantation studies used mouse BAT, and it is uncertain whether the therapeutic effect would be applied to human BAT since human and mouse BATs have distinct differences. Here, we report the fabrication of three-dimensional (3D) human brown adipose microtissues, their survival and safety, and their capability to improve glucose and insulin homeostasis and manage body weight gain in high-fat diet (HFD)-induced OB and diabetic mice.Methods3D BA microtissues were fabricated and transplanted into the kidney capsule of Rag1-/- mice. HFD was initiated to induce OB 18 days after transplantation. A low dose of streptozotocin (STZ) was administrated after three month’s HFD to induce diabetes. The body weight, fat and lean mass, plasma glucose level, glucose tolerance and insulin sensitivity were recorded regularly. In addition, the levels of human and mouse adipokines in the serum were measured, and various tissues were harvested for histological and immunostaining analyses.ResultsWe showed that 3D culture promoted BA differentiation and uncoupling protein-1 (UCP-1) protein expression, and the microtissue size significantly influenced the differentiation efficiency and UCP-1 protein level. The optimal microtissue diameter was about 100 µm. Engineered 3D BA microtissues survived for the long term with angiogenesis and innervation, alleviated body weight and fat gain, and significantly improved glucose tolerance and insulin sensitivity. They protected the endogenous BAT from whitening and reduced mouse white adipose tissue (WAT) hypertrophy and liver steatosis. In addition, the microtissues secreted soluble factors and modulated the expression of mouse adipokines. We also showed that scaling up the microtissue production could be achieved using the 3D suspension culture or a 3D thermoreversible hydrogel matrix. Further, these microtissues can be preserved at room temperature for 24 hours or be cryopreserved for the long term without significantly sacrificing cell viability.ConclusionOur study showed that 3D BA microtissues could be fabricated at large scales, cryopreserved for the long term, and delivered via injection. BAs in the microtissues had higher purity, and higher UCP-1 protein expression than BAs prepared via 2D culture. In addition, 3D BA microtissues had good in vivo survival and tissue integration, and had no uncontrolled tissue overgrowth. Furthermore, they showed good efficacy in preventing OB and T2DM with a very low dosage compared to literature studies. Thus, our results show engineered 3D BA microtissues are promising anti-OB/T2DM therapeutics. They have considerable advantages over dissociated BAs or BAPs for future clinical applications in terms of product scalability, storage, purity, quality, and in vivo safety, dosage, survival, integration, and efficacy.

DYRK1A Kinase Inhibitors Promote β-Cell Survival and Insulin Homeostasis

The rising prevalence of diabetes is threatening global health. It is known not only for the occurrence of severe complications but also for the SARS-Cov-2 pandemic, which shows that it exacerbates susceptibility to infections. Current therapies focus on artificially maintaining insulin homeostasis, and a durable cure has not yet been achieved. We demonstrate that our set of small molecule inhibitors of DYRK1A kinase potently promotes β-cell proliferation, enhances long-term insulin secretion, and balances glucagon level in the organoid model of the human islets. Comparable activity is seen in INS-1E and MIN6 cells, in isolated mice islets, and human iPSC-derived β-cells. Our compounds exert a significantly more pronounced effect compared to harmine, the best-documented molecule enhancing β-cell proliferation. Using a body-like environment of the organoid, we provide a proof-of-concept that small–molecule–induced human β-cell proliferation via DYRK1A inhibition is achievable, which lends a considerable promise for regenerative medicine in T1DM and T2DM treatment.

Genetic Risk Score for Type 2 Diabetes and Traits Related to Glucose-Insulin Homeostasis in Youth: The Exploring Perinatal Outcomes Among Children (EPOCH) Study

<em>Objective</em>: The metabolic phenotype of youth-onset type 2 diabetes (T2D) differs from that of adult-onset T2D, but little is known about genetic contributions. We aimed to evaluate the association between a T2D genetic risk score (GRS) and traits related to glucose-insulin homeostasis among healthy youth. <em>Research Design and Methods</em>: We used data from 356 youth (mean age 16.7 years, 50% female) in the EPOCH cohort to calculate a standardized weighted GRS based on 271 single nucleotide polymorphisms (SNPs) associated with T2D in adults. We used linear regression to assess associations of the GRS with log-transformed fasting glucose, 2-hour glucose, homeostasis model of insulin resistance (HOMA-IR), oral disposition index, and insulinogenic index adjusted for age, sex, body mass index (BMI) z-score, <i>in utero</i> exposure to maternal diabetes, and genetic principal components. We also evaluated effect modification by BMI z-score,<i> in utero </i>exposure to maternal diabetes and ethnicity. <em>Results</em>: Higher weighted GRS was associated with lower oral disposition index (b=-0.11; 95% CI: -0.19, -0.02) and insulinogenic index (b=-0.08; 95% CI: -0.17, -0.001), but not with fasting glucose (b=0.01; 95% CI: -0.01, 0.02), 2-hour glucose (b=0.03; 95% CI: -0.0004, 0.06), or HOMA-IR (b=0.02; 95% CI: -0.04, 0.07). BMI z-score and <i>in utero</i> exposure to maternal diabetes increased the effect of the GRS on glucose levels. <em>Conclusions</em>: Our results suggest that T2D genetic risk factors established in adults are relevant to glucose-insulin homeostasis in youth and that maintaining a healthy weight may be particularly important for youth with high genetic risk for T2D. <br> <p> </p>

Genetic Risk Score for Type 2 Diabetes and Traits Related to Glucose-Insulin Homeostasis in Youth: The Exploring Perinatal Outcomes Among Children (EPOCH) Study

<em>Objective</em>: The metabolic phenotype of youth-onset type 2 diabetes (T2D) differs from that of adult-onset T2D, but little is known about genetic contributions. We aimed to evaluate the association between a T2D genetic risk score (GRS) and traits related to glucose-insulin homeostasis among healthy youth. <em>Research Design and Methods</em>: We used data from 356 youth (mean age 16.7 years, 50% female) in the EPOCH cohort to calculate a standardized weighted GRS based on 271 single nucleotide polymorphisms (SNPs) associated with T2D in adults. We used linear regression to assess associations of the GRS with log-transformed fasting glucose, 2-hour glucose, homeostasis model of insulin resistance (HOMA-IR), oral disposition index, and insulinogenic index adjusted for age, sex, body mass index (BMI) z-score, <i>in utero</i> exposure to maternal diabetes, and genetic principal components. We also evaluated effect modification by BMI z-score,<i> in utero </i>exposure to maternal diabetes and ethnicity. <em>Results</em>: Higher weighted GRS was associated with lower oral disposition index (b=-0.11; 95% CI: -0.19, -0.02) and insulinogenic index (b=-0.08; 95% CI: -0.17, -0.001), but not with fasting glucose (b=0.01; 95% CI: -0.01, 0.02), 2-hour glucose (b=0.03; 95% CI: -0.0004, 0.06), or HOMA-IR (b=0.02; 95% CI: -0.04, 0.07). BMI z-score and <i>in utero</i> exposure to maternal diabetes increased the effect of the GRS on glucose levels. <em>Conclusions</em>: Our results suggest that T2D genetic risk factors established in adults are relevant to glucose-insulin homeostasis in youth and that maintaining a healthy weight may be particularly important for youth with high genetic risk for T2D. <br> <p> </p>

Palaeolithic diet in the treatment of type 2 diabetes

The prevalence of type 2 diabetes has steadily increased over the past few decades. In the treatment of this disease, lifestyle modifications and dietary management are essential. There is evidence suggesting a beneficial impact of the Palaeolithic diet on monitoring glucose and insulin homeostasis; however, other studies have not confirmed these results. Therefore, further well-designed trials are necessary to demonstrate the health benefits of Palaeolithic nutrition in subjects with type 2 diabetes.

Dietary Curcumin Systemically Maintains Insulin Homeostasis in Diet-Induced Aged Obese Mice via Liver-Pancreas-Brain Axis

Objectives Aging is a condition in which we gradually lose the ability to maintain homeostasis due to dysfunction. There continues to be a knowledge gap in implicating how dietary intervention affects the mechanisms delaying or preventing aging-related chronic diseases. Although curcumin (CUR), a natural antioxidant, shows the putative therapeutic properties such as reinstating insulin homeostasis in obese mice, an aging-associated mechanism in which CUR regulates insulin levels largely remains unclear. Thus, the objective of this study is to determine effects of CUR on anti-aging under obese condition mediated by maintaining insulin homeostasis via cross-talk among liver, pancreas and brain. Methods We examine how dietary CUR improves insulin clearance and maintains a proper range of circulating insulin level in the aged diet-induced obesity (DIO) mouse model. Old male C57BL/6J mice were fed a normal chow diet (NCD) or a NCD containing 0.4% (w/w) curcumin (NCD + CUR), a high fat/high sugar diet (HFHSD) or a HFHSD + CUR (N = 7–9 per group) for 16 weeks. Results Old male C57BL/6J mice were fed a normal chow diet (NCD) or a NCD containing 0.4% (w/w) curcumin (NCD + CUR), a high fat/high sugar diet (HFHSD) or a HFHSD + CUR (N = 7–9 per group) for 16 weeks. Mice given HFHSD + CUR had reduced body weight gain (4.7 ± 1.8 vs 7.8 ± 1.6g) and had lower blood insulin levels (2.24 ± 0.3 vs. 1.53 ± 0.3 ng/ml) under fasting conditions compared to mice on HFHSD alone, resulting from significantly improved insulin clearance via upregulation of hepatic insulin-degrading enzyme (IDE) and circulating IDE levels in serum. On the other hand, the expression of IDE gene in hypothalamus was significantly lower in HFHSD + CUR mice (1.3 folds) than HFHSD animals. Obesity induces hyperglycemic condition in brain by higher IDE expression to excessively break down insulin. We also observed significantly smaller islets of Langerhans (4.53 ± 0.72 vs 7.90 ± 0.34 a.u.) in HFSD + CUR fed mice and increased glucagon contents compared to HFS fed mice, indicating less secretion of insulin in pancreas under obese condition. Conclusions The conclusion of this study is that curcumin is a potent, natural therapeutic agent that can systemically regulate insulin levels in a multifaceted manner to protect against insulin resistance in aged mice. Funding Sources Intramural Research Program of NIAThe OTTOGI HAM TAIHO Foundation