Three-phasic pattern of C-peptide decline in type 1 diabetes patients with partial remission

CXCL12-CXCR4 mediates CD57+ CD8+ T cell responses in the progression of type 1 diabetes

CD57+ CD8+ T cells, also referred as effector memory cells, are implicated in various conditions including tumor immunity, virus immunity, and most recently with autoimmunity. However, their roles in the progression and remission of T1D are still unclear. Here, we noted an increase in peripheral CD57+ CD8+ T cells in a T1D patient harboring an activator of transcription 3 (STAT3) mutation. Our in-depth study on the role of CD57+ CD8+ T cells within a T1D patient cohort revealed that these cells undergo significant compositional shifts during the disease's progression. Longitudinal cohort data suggested that CD57+ CD8+ T cell prevalence may be a harbinger of β-cell function decline in T1D patients. Characterized by robust cytotoxic activity, heightened production of pro-inflammatory cytokines, and increased intracellular glucose uptake, these cells may be key players in the pathophysiology of T1D. Moreover, in vitro assays showed that the CXCL12-CXCR4 axis promotes the expansion and function of CD57+ CD8+ T cells via Erk1/2 signaling. Notably, the changes of serum CXCL12 concentrations were also found in individuals during the peri-remission phase of T1D. Furthermore, treatment with the CXCR4 antagonist LY2510924 reduced the immunological infiltration of CD57+ CD8+ T cells and mitigated hyperglycemia in a STZ-induced T1D mouse model. Taken together, our work has uncovered a novel role of the CXCL12-CXCR4 axis in driving CD57+ CD8+ T cells responses in T1D, and presented a promising therapeutic strategy for delaying the onset and progression of diabetes.

Immunometabolic biomarkers for partial remission in type 1 diabetes mellitus

Shortly after diagnosis of type 1 diabetes mellitus (T1DM) and initiation of insulin therapy, many patients experience a transient partial remission (PR) phase, also known as the honeymoon phase. This phase presents a potential therapeutic opportunity due to its association with immunoregulatory and β cell-protective mechanisms. However, the lack of biomarkers makes its characterization difficult. In this review, we cover the current literature addressing the discovery of new predictive and monitoring biomarkers that contribute to the understanding of the metabolic, epigenetic, and immunological mechanisms underlying PR. We further discuss how these peripheral biomarkers reflect attempts to arrest β cell autoimmunity and how these can be applied in clinical practice.

Glycaemia risk index uncovers distinct glycaemic variability patterns associated with remission status in type 1 diabetes

AIMS/HYPOTHESIS

The aim of this work was to define a unique remission status using glycaemia risk index (GRI) and other continuous glucose monitoring (CGM) metrics in individuals with type 1 diabetes for improved phenotyping.

METHODS

A group of 140 individuals with type 1 diabetes were recruited for a cross-sectional study. The participants were categorised into four groups based on their remission status, which was defined as insulin-dose-adjusted A1c (IDAA1c) <9 or C-peptide ≥300 pmol/l: new-onset (n=24); mid-remission (n=44); post-remission (n=44); and non-remission (individuals who did not experience remission, n=28). Participants in the remission phase were referred to as 'remitters', while those who were not in the remission phase were referred to as 'non-remitters', the latter group including new-onset, post-remission and non-remission participants. Clinical variables such as HbA1c, C-peptide and insulin daily dose, as well as IDAA1C and CGM data, were collected. The patterns of CGM metrics were analysed for each group using generalised estimating equations to investigate the glycaemic variability patterns associated with remission status. Then, unsupervised hierarchical clustering was used to place the participants into subgroups based on GRI and other CGM core metrics.

RESULTS

The glycaemic variability patterns associated with remission status were found to be distinct based on the circadian CGM metrics. Remitters showed improved control of blood glucose levels over 14 days within the range of 3.9-10 mmol/l, and lower GRI compared with non-remitters (p<0.001). Moreover, GRI strongly correlated with IDAA1C (r=0.62; p<0.001) and was sufficient to distinguish remitters from non-remitters. Further, four subgroups demonstrating distinct patterns of glycaemic variability associated with different remission status were identified by clustering on CGM metrics: remitters with low risk of dysglycaemia; non-remitters with high risk of hypoglycaemia; non-remitters with high risk of hyperglycaemia; and non-remitters with moderate risk of dysglycaemia.

CONCLUSIONS/INTERPRETATION

GRI, an integrative index, together with other traditional CGM metrics, helps to identify different glycaemic variability patterns; this might provide specifically tailored monitoring and management strategies for individuals in the various subclusters.

Fat-to-muscle ratio is associated with insulin resistance and cardiometabolic disorders in adults with type 1 diabetes mellitus

AIMS

This study aimed to investigate the correlation of the fat-to-muscle ratio (FMR) with insulin resistance (IR) and cardiometabolic disorders (CMD) in patients with type 1 diabetes mellitus (T1DM).

MATERIALS AND METHODS

We retrospectively recruited 420 adults with T1DM [52.6% men, median age 32.4 (24.5, 43.0) years]. Body composition was assessed by bioelectrical impedance analysis and FMR was calculated. The characteristics of the overall participants were compared between tertiles of FMR. Logistic regression analyses were performed to assess the association of FMR tertiles with IR and cardiometabolic risk factors.

RESULTS

Median age and median haemoglobin A1c of all participants were 32.4 (24.5, 43.0) years and 7.4 (6.5, 8.7)%, respectively. The prevalence of IR and CMD was 18% and 38.6%. The FMR significantly differed between men and women [0.39 (0.31, 0.53) vs. 0.74 (0.63, 0.92), respectively, p < .001]. The proportion of IR and CMD gradually increased as the FMR increased. The multivariable-adjusted odd ratios for IR and CMD in FMR tertile 3 compared with tertile 1 were 4.8 [95% confidence interval (CI): (1.9, 12.1)] and 9.7 (95% CI: 4.2, 22.3), respectively, in men. For women, the corresponding odd ratios were 4.0 (95% CI: 1.2, 12.9) for IR and 5.8 (95% CI: 2.4, 13.6) for CMD.

CONCLUSIONS

FMR is associated with IR and CMD in adults with T1DM and could be used as a promising parameter for targeting treatment in T1DM.

Insulin resistance is more frequent in type 1 diabetes patients with long disease duration

AIMS

To investigate the clinical status of insulin resistance (IR) and its correlation with disease duration in patients with type 1 diabetes (T1D).

MATERIALS AND METHODS

Cross-sectional data from a T1D cohort were obtained (n = 923). IR-related metabolic disorders including hypertension, obesity, and dyslipidemia were used as outcome variables to explore the cut-off point for estimated glucose disposal rate (eGDR) by restricted cubic spline (RCS) curve. Regression models were used for multivariate analysis of the clinical factors associated with IR. The correlation between the status of IR and diabetes duration was depicted with the RCS curve.

RESULTS

IR-related metabolic disorders were observed in 39.4% of patients, with 9.1% meeting the criteria for metabolic syndrome. Specifically, patients with ≥10 years of T1D were more likely to have IR-related metabolic disorders (54.7% vs. 36.9%, p < 0.05). The presence of IR, defined as an eGDR ≤9.0 mg/kg/min, was observed in 42.2% of patients. Patients with IR had a longer diabetes duration (3.5 vs. 2.7, years, p = 0.003) and higher insulin dose (0.5 vs. 0.4, units per kg per day, p < 0.001). Moreover, the presence of IR showed a gradual increase during 10 years' disease duration and further analysis showed that diabetes duration ≥10 years was a key element behind the development of IR and IR-related metabolic disorders.

CONCLUSIONS

The status of IR is common in T1D patients, especially in those with ≥10 years of disease duration. Therapies targeting balancing glycaemic control and IR are needed to decrease the future risk of cardiovascular diseases in T1D.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT03610984 (cohort study of patients with type 1 diabetes).

Recovery of intracellular glucose uptake in T cells during partial remission of type 1 diabetes

AIMS/HYPOTHESIS

Notwithstanding the irreversible beta cell failure seen in type 1 diabetes, some individuals may experience a special phase named 'partial remission' or 'the honeymoon period', in which there is a transient recovery of beta cell function. Importantly, this stage of partial remission shows spontaneous immune downregulation, although the exact mechanisms are unclear. Intracellular energy metabolism is crucial for the differentiation and function of T cells, and provides promising targets for immunometabolic intervention strategies, but its role during partial remission is unknown. In this study, we aim to investigate the association between T cell intracellular glucose and fatty acid metabolism and the partial remission phase.

METHODS

This is a cross-sectional study with a follow-up component. Intracellular uptake of glucose and fatty acids by T cells was detected in participants with either new-onset type 1 diabetes or type 1 diabetes that was already in partial remission, and compared with heathy individuals and participants with type 2 diabetes. Subsequently, the participants with new-onset type 1 diabetes were followed up to determine whether they experienced a partial remission (remitters) or not (non-remitters). The trajectory of changes in T cell glucose metabolism was observed in remitters and non-remitters. Expression of programmed cell death-1 (PD-1) was also analysed to investigate possible mechanisms driving altered glucose metabolism. Partial remission was defined when patients had convalescent fasting or 2 h postprandial C-peptide >300 pmol/l after insulin treatment.

RESULTS

Compared with participants with new-onset type 1 diabetes, intracellular glucose uptake by T cells decreased significantly in individuals with partial remission. The trajectory of these changes during follow-up showed that intracelluar glucose uptake in T cells fluctuated during different disease stages, with a decreased uptake during partial remission that rebounded after remission. This dynamic in T cell glucose uptake was only detected in remitters and not in non-remitters. Further analysis demonstrated that changes of intracellular glucose uptake were found in subsets of CD4+ and CD8+ T cells, including Th17, Th1, CD8+ naive T cells (Tn) and CD8+ terminally differentiated effector memory T cells (Temra). Moreover, glucose uptake in CD8+ T cells was negatively related to PD-1 expression. The intracellular metabolism of fatty acids was not found to be different between new-onset participants and those in partial remission.

CONCLUSIONS/INTERPRETATION

Intracellular glucose uptake in T cells was specifically decreased during partial remission in type 1 diabetes and may be related to PD-1 upregulation, which may be involved in the down-modulation of immune responses during partial remission. This study suggests that altered immune metabolism could be a target for interventions at the point of diagnosis of type 1 diabetes.

Enhanced T Cell Glucose Uptake Is Associated With Progression of Beta-Cell Function in Type 1 Diabetes

Background

Abnormal intracellular glucose/fatty acid metabolism of T cells has tremendous effects on their immuno-modulatory function, which is related to the pathogenesis of autoimmune diseases. However, the association between the status of intracellular metabolism of T cells and type 1 diabetes is unclear. This study aimed to investigate the uptake of glucose and fatty acids in T cells and its relationship with disease progression in type 1 diabetes.

Methods

A total of 86 individuals with type 1 diabetes were recruited to detect the uptake of glucose and fatty acids in T cells. 2-NBDG uptake and expression of glucose transporter 1 (GLUT1); or BODIPY uptake and expression of carnitine palmitoyltransferase 1A(CPT1A) were used to assess the status of glucose or fatty acid uptake in T cells. Patients with type 1 diabetes were followed up every 3-6 months for 36 months, the progression of beta-cell function was assessed using generalized estimating equations, and survival analysis was performed to determine the status of beta-cell function preservation (defined as 2-hour postprandial C-peptide >200 pmol/L).

Results

Patients with type 1 diabetes demonstrated enhanced intracellular glucose uptake of T cells as indicated by higher 2NBDG uptake and GLUT1 expression, while no significant differences in fatty acid uptake were observed. The increased T cells glucose uptake is associated with lower C-peptide and higher hemoglobin A1c levels. Notably, patients with low T cell glucose uptake at onset maintained high levels of C-peptide within 36 months of the disease course [fasting C-petite and 2-hour postprandial C-peptide are 60.6 (95%CI: 21.1-99.8) pmol/L and 146.3 (95%CI: 14.1-278.5) pmol/L higher respectively], And they also have a higher proportion of beta-cell function preservation during this follow-up period (P<0.001).

Conclusions

Intracellular glucose uptake of T cells is abnormally enhanced in type 1 diabetes and is associated with beta-cell function and its progression.