Reduced hepatocellular lipid accumulation and energy metabolism in patients with long standing type 1 diabetes mellitus

31P-MRS saturation transfer for assessing human hepatic ATP synthesis at clinical field strength

BACKGROUND

31P-magnetic resonance spectroscopy (MRS) saturation transfer (ST) allows for noninvasive investigation of liver energy metabolism by assessing flux rates of adenosine triphosphate (ATP) synthesis. However, this technique has rarely been applied at clinical field strengths because of long examination times and contamination from muscle tissue. Our aim was to establish a new method to robustly assess ATP synthesis using a clinical scanner.

METHODS

A prospective single-center study was performed (January 2023-August 2024) within the German Diabetes Study. We established a suitable 31P-MRS ST protocol, tested it in vitro and in vivo and assessed its reproducibility. We assessed the hepatic apparent spin-lattice relaxation time of inorganic phosphate (T 1 , P i ' ), equilibrium forward rate constant (k f ), and forward ATP synthesis rate (F A T P ) in nine control volunteers (CON) (six females) and eight patients (five females) with type 1 diabetes (T1D) and compared differences by ANOVA.

RESULTS

Reproducibility assessment in nine CON, aged 27 ± 4 years (mean ± standard deviation), yielded coefficients of variation for repeated measurements of 7.1% and 21.3% forT 1 , P i ' andk f , respectively. Group comparison revealed higher hepatick f (0.34 ± 0.03 s-1 versus 0.16 ± 0.03 s-1; p = 0.001) andF A T P (35.3 ± 3.5 mM/min versus 16.4 ± 3.5 mM/min; p = 0.002) in CON than in T1D, aged 42 ± 15 years, respectively.

CONCLUSION

This 31P-MRS ST method allowed for robust assessment of hepatic ATP synthesis at clinical field strength and was sensitive enough to detect differences between CON and T1D volunteers.

RELEVANCE STATEMENT

Noninvasive methods to investigate hepatic energy metabolism are urgently needed to evaluate liver health while preventing unnecessary biopsies. For broad clinical applicability, the robustness shown by the proposed method at clinical field strength is crucial.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01055093-Prospective study on diabetes mellitus and its complications in newly diagnosed adult patients (GDC), NCT01055093, Registered: 01/22/2010, https://clinicaltrials.gov/study/NCT01055093?term=NCT01055093&rank=1#study-overview .

KEY POINTS

The proposed magnetic resonance spectroscopy method calculates hepatic ATP synthesis rates at clinical field strength. The protocol shows acceptable reproducibility and spectra without contamination from muscle. The method can detect differences between participants with type 1 diabetes and controls.

Concentric remodeling and the metabolic-associated steatotic liver disease in patients with type 1 diabetes: an exploratory study

INTRODUCTION

Diabetic cardiomyopathy in young patients with type 1 diabetes (T1D) usually presents as asymptomatic diastolic heart dysfunction with left ventricle (LV) remodeling. Its prevalence seems to be underestimated. One of the factors seemingly influencing LV remodeling is a metabolic-associated steatotic liver disease (MASLD), which was extensively investigated in patients with type 2 diabetes but not with T1D. This study aimed to describe the correlation between MASLD risk and relative wall thickness (RWT) in young patients with T1D without heart failure symptoms or treatment.

MATERIALS AND METHODS

Study participants were recruited at the inpatient diabetology department, in admission order. Patients underwent a set of laboratory tests and echocardiographic examinations. The risk of MASLD was estimated using fatty liver index (FLI). Acquired data was then statistically analyzed.

RESULTS

The study group consisted of 55 patients. 25 participants had RWT > 0.42, suggesting LV remodeling. Study participants did not differ in HbA1c, NT-proBNP, HDL, LDL, non-HDL, and uric acid concentrations. However, patients with RWT > 0.42 had higher FLI (40.97 vs. 13.82, p < 0.01) and BMI (27.3 vs. 22.5, p < 0.01) and differed in transaminase concentrations. Moreover, patients with RWT > 0.42 had significantly higher LV mass index (85.6 vs. 68.2 g/m2) and altered mitral ring velocities. In univariable logistic regression, FLI correlated with LV remodeling risk (OR 1.028, p = 0.05). The optimal cutoff point for FLI predicting the RWT > 0.42 was 26.38 (OR 10.6, p = 0.04, sensitivity 0.857, specificity 0.657).

CONCLUSIONS

FLI correlates with RWT in patients with T1D independently of diabetes metabolic control and hypothetically may support recognizing T1D patients with a higher risk of LV remodeling.

Intramyocellular Triglyceride Content During the Early Course of Type 1 and Type 2 Diabetes

Intramyocellular lipid content (IMCL) is elevated in insulin-resistant humans, but it changes over time, and relationships with comorbidities remain unclear. We examined IMCL during the initial course of diabetes and its associations with complications. Participants of the German Diabetes Study (GDS) with recent-onset type 1 (n = 132) or type 2 diabetes (n = 139) and glucose-tolerant control subjects (n = 128) underwent 1H-MRS to measure IMCL and muscle volume, whole-body insulin sensitivity (hyperinsulinemic-euglycemic clamps; M-value), and cycling spiroergometry (VO2max). Subgroups underwent the same measurements after 5 years. At baseline, IMCL was ∼30% higher in type 2 diabetes than in other groups independently of age, sex, BMI, and muscle volume. In type 2 diabetes, the M-value was ∼36% and ∼62% lower compared with type 1 diabetes and control subjects, respectively. After 5 years, the M-value decreased by ∼29% in type 1 and ∼13% in type 2 diabetes, whereas IMCL remained unchanged. The correlation between IMCL and M-value in type 2 diabetes at baseline was modulated by VO2max. IMCL also associated with microalbuminuria, the Framingham risk score for cardiovascular disease, and cardiac autonomic neuropathy. Changes in IMCL within 5 years after diagnosis do not mirror the progression of insulin resistance in type 2 diabetes but associate with early diabetes-related complications.

ARTICLE HIGHLIGHTS

Intramyocellular lipid content (IMCL) can be elevated in insulin-resistant humans, but its dynamics and association with comorbidities remain unclear. Independently of age, sex, body mass, and skeletal muscle volume, IMCL is higher in recent-onset type 2, but not type 1 diabetes, and remains unchanged within 5 years, despite worsening insulin resistance. A degree of physical fitness modulates the association between IMCL and insulin sensitivity in type 2 diabetes. Whereas higher IMCL associates with lower insulin sensitivity in people with lower physical fitness, there is no association between IMCL and insulin sensitivity in those with higher degree of physical fitness. IMCL associates with progression of microalbuminuria, cardiovascular disease risk, and cardiac autonomic neuropathy.

Increased GH/IGF-I Axis Activity Relates to Lower Hepatic Lipids and Phosphor Metabolism

CONTEXT

Non-alcoholic fatty liver disease (NAFLD) is a leading causes of liver-related morbidity and mortality. While data on acromegaly, a state of chronic growth hormone (GH)/insulin-like growth factor I (IGF-I) excess, suggest an inverse relationship with intrahepatic lipid (IHL) content, less is known about the impact of the GH/IGF-I axis on IHL, lipid composition, and phosphor metabolites in individuals without disorders of GH secretion.

OBJECTIVE

The aim was to investigate the relation between activity of the GH/IGF-I axis and IHL content and phosphor metabolism.

METHODS

We performed a cross-sectional study in 59 otherwise metabolically healthy individuals (30 females), of which 16 met the criteria of NAFLD with IHL of ≥5.6%. The GH/IGF-I axis was evaluated in a fasting state and during an oral glucose tolerance test (OGTT). Insulin sensitivity was estimated by validated indices. IHL, lipid composition (unsaturation index), and phosphate metabolites were analyzed by using 1H/31P magnetic resonance spectroscopy.

RESULTS

In the overall cohort (40.6 ± 15 years; body mass index: 24.5 ± 3 kg/m2; IGF-I: 68.0 ± 17% upper limit of normal), fasting GH (R = -0.31; P = .02), GH during oral glucose tolerance test (R = -0.51; P < .01), and IGF-I (R = -0.28; P = .03) inversely correlated with IHL. GH levels during OGTT were significantly lower in NAFLD than in controls (47.7 [22; 143] ng/mL/min vs 16.8 [7; 32] ng/mL/min; P = .003). GH/IGF-I axis activity correlated with lipid composition and with phosphor metabolites. In multiple regression analysis, the GH/IGF-I axis activity was a strong predictor for IHL and lipid composition independent from insulin sensitivity.

CONCLUSION

GH/IGF-I axis activity impacts hepatic lipid and phosphate metabolism in individuals without disorders in GH secretion. Lower GH axis activity is associated with higher IHL and an unfavorable lipid composition, probably mediated by changes in hepatic energy metabolism.

Alterations of hepatic energy metabolism in murine models of obesity, diabetes and fatty liver diseases

BACKGROUND

Disturbed hepatic energy metabolism contributes to non-alcoholic fatty liver (NAFLD), but the development of changes over time and obesity- or diabetes-related mechanisms remained unclear.

METHODS

Two-day old male C57BL/6j mice received streptozotocin (STZ) or placebo (PLC) and then high-fat (HFD) or regular chow diet (RCD) from week 4 (W4) to either W8 or W16, yielding control [CTRL = PLC + RCD], diabetes [DIAB = STZ + RCD], obesity [OBES = PLC + HFD] and diabetes-related non-alcoholic steatohepatitis [NASH = STZ + HFD] models. Mitochondrial respiration was measured by high-resolution respirometry and insulin-sensitive glucose metabolism by hyperinsulinemic-euglycemic clamps with stable isotope dilution.

FINDINGS

NASH showed higher steatosis and NAFLD activity already at W8 and liver fibrosis at W16 (all p < 0.01 vs CTRL). Ballooning was increased in DIAB and NASH at W16 (p < 0.01 vs CTRL). At W16, insulin sensitivity was 47%, 58% and 75% lower in DIAB, NASH and OBES (p < 0.001 vs CTRL). Hepatic uncoupled fatty acid oxidation (FAO)-associated respiration was reduced in OBES at W8, but doubled in DIAB and NASH at W16 (p < 0.01 vs CTRL) and correlated with biomarkers of unfolded protein response (UPR), oxidative stress and hepatic expression of certain enzymes (acetyl-CoA carboxylase 2, Acc2; carnitine palmitoyltransferase I, Cpt1a). Tricarboxylic acid cycle (TCA)-driven respiration was lower in OBES at W8 and doubled in DIAB at W16 (p < 0.0001 vs CTRL), which positively correlated with expression of genes related to lipolysis.

INTERPRETATION

Hepatic mitochondria adapt to various metabolic challenges with increasing FAO-driven respiration, which is linked to dysfunctional UPR, systemic oxidative stress, insulin resistance and altered lipid metabolism. In a diabetes model, higher TCA-linked respiration reflected mitochondrial adaptation to greater hepatic lipid turnover.

FUNDING

Funding bodies that contributed to this study were listed in the acknowledgements section.

Insulin Resistance in Experimental Type 1 Diabetes Mellitus

Experimental type 1 diabetes mellitus (T1DM) was induced in rats by daily intraperitoneal injections of alloxan in a dose of 90 mg/kg for 4 days. For verification of insulin resistance, insulin tolerance test was performed in 2 weeks and the glucose utilization rate constant (K_ITT) was calculated. The rats demonstrated the main symptoms of T1DM: hypoinsulinemia, hyperglycemia, ketonemia, glucosuria, ketonuria, polydipsia, polyphagia, weight loss, and insulin resistance, as evidenced by a decrease in K_ITT. The serum content of free fatty acids and triacylglycerols significantly increased. The content of triacylglycerols increased in skeletal muscles and decreased in the liver. A negative linear correlation was found between K_ITT and triacylglycerol content in muscles. Thus, the development of insulin resistance in experimental T1DM in rats is associated with accumulation of triacylglycerols in skeletal muscles.

Prevalence of non-alcoholic fatty liver disease (NAFLD) and its association with surrogate markers of insulin resistance in patients with type 1 diabetes

AIMS

Assess prevalence of hepatic steatosis (HS) and of fibrosis in an unselected population of patients with type 1 diabetes. Describe their clinical profile and explore the association between insulin resistance and NAFLD as secondary objectives.

METHODS

We prospectively assessed NAFLD by transient elastography in adult outpatients with type 1 diabetes. Patients were eligible if they did not have any known secondary cause of liver disease. NAFLD was defined as HS with or without fibrosis/cirrhosis. Associations between estimated glucose disposal rate (eGDR) and metabolic syndrome, as surrogate markers of insulin resistance, and NAFLD were explored using multivariate logistic regression models, adjusting for age, sex and diabetes duration.

RESULTS

We enrolled 150 consecutive subjects (age 47 ± 14 years, male 55%, diabetes duration 25 ± 14 years, median BMI 25 kg/m²). NAFLD prevalence was 20% (n = 30). Thirty patients (20%) had HS. Five patients (3.3%) had HS with fibrosis. eGDR and metabolic syndrome were statistically significantly associated with the presence of NAFLD (OR 0.62, 95% CI 0.49-0.77, OR 7.62, 95% CI 2.95-19.77).

CONCLUSIONS

NAFLD prevalence in patients with type 1 diabetes is considerable, mainly restricted to isolated HS, while fibrosis is rare. Insulin resistance is associated with NAFLD in patients with type 1 diabetes.

Metabolic impacts of cordycepin on hepatic proteomic expression in streptozotocin-induced type 1 diabetic mice

Type 1 Diabetes mellitus (T1DM) is associated with abnormal liver function, but the exact mechanism is unclear. Cordycepin improves hepatic metabolic pathways leading to recovery from liver damage. We investigated the effects of cordycepin in streptozotocin-induced T1DM mice via the expression of liver proteins. Twenty-four mice were divided into four equal groups: normal (N), normal mice treated with cordycepin (N+COR), diabetic mice (DM), and diabetic mice treated with cordycepin (DM+COR). Mice in each treatment group were intraperitoneally injection of cordycepin at dose 24 mg/kg for 14 consecutive days. Body weight, blood glucose, and the tricarboxylic acid cycle intermediates were measured. Liver tissue protein profiling was performed using shotgun proteomics, while protein function and protein-protein interaction were predicted using PANTHER and STITCH v.5.0 software, respectively. No significant difference was observed in fasting blood glucose levels between DM and DM+COR for all time intervals. However, a significant decrease in final body weight, food intake, and water intake in DM+COR was found. Hepatic oxaloacetate and citrate levels were significantly increased in DM+COR compared to DM. Furthermore, 11 and 36 proteins were only expressed by the N+COR and DM+COR groups, respectively. Three unique proteins in DM+COR, namely, Nfat3, Flcn, and Psma3 were correlated with the production of ATP, AMPK signaling pathway, and ubiquitin proteasome system (UPS), respectively. Interestingly, a protein detected in N+COR and DM+COR (Gli3) was linked with the insulin signaling pathway. In conclusion, cordycepin might help in preventing hepatic metabolism by regulating the expression of energy-related protein and UPS to maintain cell survival. Further work on predicting the performance of metabolic mechanisms regarding the therapeutic applications of cordycepin will be performed in future.

Feasibility of Hepatic Fat Quantification Using Proton Density Fat Fraction by Multi-Echo Chemical-Shift-Encoded MRI at 7T

Fat fraction quantification and assessment of its distribution in the hepatic tissue become more important with the growing epidemic of obesity, and the increasing prevalence of diabetes mellitus type 2 and non-alcoholic fatty liver disease. At 3Tesla, the multi-echo, chemical-shift-encoded magnetic resonance imaging (CSE-MRI)-based acquisition allows the measurement of proton density fat-fraction (PDFF) even in clinical protocols. Further improvements in SNR can be achieved by the use of phased array coils and increased static magnetic field. The purpose of the study is to evaluate the feasibility of PDFF imaging using a multi-echo CSE-MRI technique at ultra-high magnetic field (7Tesla). Thirteen volunteers (M/F) with a broad range of age, body mass index, and hepatic PDFF were measured at 3 and 7T by multi-gradient-echo MRI and single-voxel spectroscopy MRS. All measurements were performed in breath-hold (exhalation); the MRI protocols were optimized for a short measurement time, thus minimizing motion-related problems. 7T data were processed off-line using Matlab® (MRI:multi-gradient-echo) and jMRUI (MRS), respectively. For quantitative validation of the PDFF results, a similar protocol was performed at 3T, including on-line data processing provided by the system manufacturer, and correlation analyses between 7 and 3T data were performed off-line. The multi-echo CSE-MRI measurements at 7T with a phased-array coil configuration and an optimal post-processing yielded liver volume coverage ranging from 30 to 90% for high- and low-BMI subjects, respectively. PDFFs ranged between 1 and 20%. We found significant correlations between 7T MRI and -MRS measurements (R² ≅ 0.97; p < 0.005), and between MRI-PDFF at 7T and 3T fields (R² ≅ 0.94; p < 0.005) in the evaluated volumes. Based on the measurements and analyses performed, the multi-echo CSE-MRI method using a 32-channel coil at 7T showed its aptitude for MRI-based quantitation of PDFF in the investigated volumes. The results are the first step toward qMRI of the whole liver at 7T with further improvements in hardware.

Early changes in hepatic energy metabolism and lipid content in recent-onset type 1 and 2 diabetes mellitus

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is associated with abnormal mitochondrial capacity. While oxidative capacity can be increased in steatosis, hepatic ATP decreases in long-standing diabetes. However, longitudinal studies on diabetes-related NAFLD and its relationship to hepatic energy metabolism are lacking.

METHODS

This prospective study comprised volunteers with type 1 (T1DM, n = 30) and type 2 (T2DM, n = 37) diabetes. At diagnosis and 5 years later, we used ¹H/³¹P magnetic resonance spectroscopy to measure hepatocellular lipid (HCL), γATP and inorganic phosphate (Pi) concentrations, and to assess adipose tissue volumes. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps.

RESULTS

At diagnosis, individuals with T2DM had higher HCL and adipose tissue volumes, but lower whole-body insulin sensitivity than those with T1DM, despite comparable glycemic control. NAFLD was present in 38% of individuals with T2DM and 7% with T1DM. After 5 years, visceral adipose tissue only increased in individuals with T2DM, while HCL almost doubled in this group (p <0.001), resulting in a 70% prevalence of NAFLD (independent of diabetes treatment). Changes in HCL correlated with adipose tissue volume and insulin resistance (r = 0.50 and r = 0.44, both p <0.05). Pi decreased by 17% and 10% in individuals with T2DM and T1DM (p <0.05), respectively. In T1DM, HCL did not change, whereas γATP decreased by 10% and correlated negatively with glycated hemoglobin (r = -0.56, p <0.05).

CONCLUSIONS

The rapid increase in HCL during the early course of T2DM likely results from enlarging adipose tissue volume and insulin resistance in response to impaired hepatic mitochondrial adaptation. The decrease of phosphorus metabolites in T1DM may be due to pharmacological insulin supply.

LAY SUMMARY

Previous studies suggested that the impaired function of mitochondria, the power plants of cells, can promote fatty liver and type 2 diabetes mellitus. This study now shows that during the first 5 years of type 2 diabetes the increase in body fat content rapidly leads to a doubling of liver fat content, whereas the energy metabolism of the patients' livers progressively declines. These data suggest that fat tissue mass and liver mitochondria have an important role in the development of fatty liver disease in humans with diabetes.

CLINICAL TRIAL NUMBER

NCT01055093.

The Prevalence of Nonalcoholic Fatty Liver Disease and Its Risk Factors in Children and Young Adults with Type 1 Diabetes Mellitus

OBJECTIVES

To determine the prevalence of nonalcoholic fatty liver disease (NAFLD) and its associated risk factors in children and young adults with type 1 diabetes (T1D).

STUDY DESIGN

A cross-sectional study was conducted at a tertiary care center in children and young adults with T1D. Liver fat quantification and hepatic fibrosis were assessed by magnetic resonance imaging proton density fat fraction and magnetic resonance elastography (MRE). Logistic regression analysis was performed to examine the associated risk factors for NAFLD.

RESULTS

Fifty patients with T1D (28 females, 13 with overweight/obesity) were included. The median age and duration of T1D were 16.9 years (IQR, 13.6-20 years) and 6.5 years (IQR, 4-11 years), respectively. The prevalence of NAFLD was 10%. Four out of 5 patients with NAFLD were overweight/obese, and 2 had an and elevated alanine aminotransferase (ALT) level. None had liver fibrosis (defined as MRE >2.9 kPa). Compared with patients without NAFLD, patients with NAFLD had significantly higher body mass index standard deviation score (BMI-SDS) (median, 0.94 [IQR, 1.30-2.62] vs 0.13 [IQR, -0.69 to 0.84]; P = .01), ALT (median, 17 IU/L [IQR, 16-52 IU/L] vs 12 IU/L [IQR, 10-14 IU/L]; P = .02), and lower high-density lipoprotein cholesterol (median, 49 mg/dL [IQR, 41-51 mg/dL] vs 57 mg/dL [IQR, 52-69 mg/dL]; P = .039). Multivariate logistic regression analysis identified high BMI-SDS as the sole independent risk factor associated with NAFLD (OR, 5.79; 95% CI, 1.04-32.18).

CONCLUSION

The prevalence of NAFLD in children and young adults with T1D was comparable to that in the general population. Our study suggests that routine screening for NAFLD in patients with T1D might not be necessary but should be performed in those patients with T1D who are overweight/obese.

Targeting Leukotrienes as a Therapeutic Strategy to Prevent Comorbidities Associated with Metabolic Stress

Leukotrienes (LTs) are potent lipid mediators that exert a variety of functions, ranging from maintaining the tone of the homeostatic immune response to exerting potent proinflammatory effects. Therefore, LTs are essential elements in the development and maintenance of different chronic diseases, such as asthma, arthritis, and atherosclerosis. Due to the pleiotropic effects of LTs in the pathogenesis of inflammatory diseases, studies are needed to discover potent and specific LT synthesis inhibitors and LT receptor antagonists. Even though most clinical trials using LT inhibitors or antagonists have failed due to low efficacy and/or toxicity, new drug development strategies are driving the discovery for LT inhibitors to prevent inflammatory diseases. A newly important detrimental role for LTs in comorbidities associated with metabolic stress has emerged in the last few years and managing LT production and/or actions could represent an exciting new strategy to prevent or treat inflammatory diseases associated with metabolic disorders. This review is intended to shed light on the synthesis and actions of leukotrienes, the most common drugs used in clinical trials, and discuss the therapeutic potential of preventing LT function in obesity, diabetes, and hyperlipidemia.

Metabolite cycled liver 1 H MRS on a 7 T parallel transmit system

INTRODUCTION

Single-voxel ¹ H MRS in body applications often suffers from respiratory and other motion induced phase and frequency shifts, which lead to incoherent averaging and hence to suboptimal results.

METHODS

Here we show the application of metabolite cycling (MC) for liver STEAM-localized ¹ H MRS on a 7 T parallel transmit system, using eight transmit-receive fractionated dipole antennas with 16 additional, integrated receive loops. MC-STEAM measurements were made in six healthy, lean subjects and compared with STEAM measurements using VAPOR water suppression. Measurements were performed during free breathing and during synchronized breathing, for which the subjects did breathe in between the MRS acquisitions. Both intra-session repeatability and inter-session reproducibility of liver lipid quantification with MC-STEAM and VAPOR-STEAM were determined.

RESULTS

The preserved water signal in MC-STEAM allowed for robust phase and frequency correction of individual acquisitions before averaging, which resulted in in vivo liver spectra that were of equal quality when measurements were made with free breathing or synchronized breathing. Intra-session repeatability and inter-session reproducibility of liver lipid quantification were better for MC-STEAM than for VAPOR-STEAM. This may also be explained by the more robust phase and frequency correction of the individual MC-STEAM acquisitions as compared with the VAPOR-STEAM acquisitions, for which the low-signal-to-noise ratio lipid signals had to be used for the corrections.

CONCLUSION

Non-water-suppressed MC-STEAM on a 7 T system with parallel transmit is a promising approach for ¹ H MRS applications in the body that are affected by motion, such as in the liver, and yields better repeatability and reproducibility compared with water-suppressed measurements.