Pathophysiology of immune-mediated (type 1) diabetes mellitus: potential for immunotherapy

Autoimmune diabetes from pembrolizumab: A case report and review of literature

BACKGROUND

Immunotherapy, specifically the use of checkpoint inhibitors such as pembrolizumab, has become an important tool in personalized cancer therapy. These inhibitors target proteins on T-cells that regulate the immune response against tumor cells. Pembrolizumab, which targets the programmed cell death 1 receptor on T-cells, has been approved for the treatment of metastatic melanoma and non-small cell lung cancer. However, it can also lead to immune-related side effects, including pneumonitis, colitis, thyroid abnormalities, and rare cases of type 1 diabetes.

CASE SUMMARY

The case presented involves an adult patient in 30s with breast cancer who developed hyperglycemia after receiving pembrolizumab treatment. The patient was diagnosed with diabetic ketoacidosis and further investigations were performed to evaluate for new-onset type 1 diabetes. The patient had a history of hypothyroidism and a family history of breast cancer. Treatment for diabetic ketoacidosis was initiated, and the patient was discharged for close follow-up with an endocrinologist.

CONCLUSION

This literature review highlights the occurrence of diabetic ketoacidosis and new-onset type 1 diabetes in patients receiving pembrolizumab treatment for different types of cancer. Overall, the article emphasizes the therapeutic benefits of immunotherapy in cancer treatment, particularly pembrolizumab, while also highlighting the potential side effect of immune-related diabetes that can occur in a small percentage of patients. Here we present a case where pembrolizumab lead to development of diabetes after a few cycles highlighting one of the rare yet a serious toxicity of the drug.

Adherence as a Predictor of Glycemic Control Among Adolescents With Type 1 Diabetes: A Retrospective Study Using Real-World Evidence

PURPOSE

Metabolic control among adolescents with type 1 diabetes mellitus (T1DM) is generally poor. Nonadherence is a contributor to this poor glycemic control, leading to adverse outcomes. The findings of studies reporting the association between adherence and glycemic control are conflicting. This study aimed to assess the level of adherence among adolescents with T1DM and its relationship with glycemic control.

METHODS

This was a retrospective, cross-sectional study that was conducted at Sidra Medicine, a state-of-the-art tertiary health care facility for women and children in Qatar. Mean blood or interstitial glucose monitoring frequency (BGMF) was used to assess adherence level among adolescents with T1DM, whereas glycemic control was assessed via documented glycated hemoglobin A_1c (HbA_1c). Adolescents who had a mean BGMF of ≥4 checks per day were considered adherent, and those who had an HbA_1c level of <7% were considered as having controlled diabetes. Correlational and logistic regression analyses were performed to assess the relationship between adherence and glycemic control, incorporating other covariates into the model.

FINDINGS

The rate of adherence among adolescents with T1DM in Qatar was 40.9%. Adherent adolescents had significantly lower median HbA_1c levels compared with nonadherent adolescents (9.0% vs. 9.7%; P = 0.002). A significant negative correlation was found between BGMF and HbA_1c level (correlation coefficient r_s = -0.325; P < .001). Approximately 97% of nonadherent adolescents compared with 87% of adherent adolescents had suboptimal diabetes control (HbA_1c ≥7%) (P = .016). Furthermore, nonadherent adolescents were 78% less likely to have controlled diabetes compared with adherent adolescents (adjusted odds ratio = 0.221; 95% CI, 0.063-0.778; P = 0.019). The combined effect of the determinants of glycemic control among adolescents with T1DM that were included in the multiple regression model was able to explain approximately 9% of the variances in glycemic control (Cox and Snell R² = 0.092).

IMPLICATIONS

The current findings suggest that nonadherence was highly prevalent among adolescents with T1DM and was a significant independent predictor of glycemic control, explaining 9% of the variability. This finding warrants further exploration of other possible predictors of poor glycemic control among the adolescent population. Comprehensive interventions, including educational, technological, and health service delivery aspects, aimed at improving adherence and ultimately optimizing glycemic control are warranted in adolescents with T1DM.

Methods to assess beta cell death mediated by cytotoxic T lymphocytes

Type 1 diabetes (T1D) is a T cell mediated autoimmune disease. During the pathogenesis, patients become progressively more insulinopenic as insulin production is lost, presumably this results from the destruction of pancreatic beta cells by T cells. Understanding the mechanisms of beta cell death during the development of T1D will provide insights to generate an effective cure for this disease. Cell-mediated lymphocytotoxicity (CML) assays have historically used the radionuclide Chromium 51 ((51)Cr) to label target cells. These targets are then exposed to effector cells and the release of (51)Cr from target cells is read as an indication of lymphocyte-mediated cell death. Inhibitors of cell death result in decreased release of (51)Cr. As effector cells, we used an activated autoreactive clonal population of CD8(+) Cytotoxic T lymphocytes (CTL) isolated from a mouse stock transgenic for both the alpha and beta chains of the AI4 T cell receptor (TCR). Activated AI4 T cells were co-cultured with (51)Cr labeled target NIT cells for 16 hours, release of (51)Cr was recorded to calculate specific lysis Mitochondria participate in many important physiological events, such as energy production, regulation of signaling transduction, and apoptosis. The study of beta cell mitochondrial functional changes during the development of T1D is a novel area of research. Using the mitochondrial membrane potential dye Tetramethyl Rhodamine Methyl Ester (TMRM) and confocal microscopic live cell imaging, we monitored mitochondrial membrane potential over time in the beta cell line NIT-1. For imaging studies, effector AI4 T cells were labeled with the fluorescent nuclear staining dye Picogreen. NIT-1 cells and T cells were co-cultured in chambered coverglass and mounted on the microscope stage equipped with a live cell chamber, controlled at 37°C, with 5% CO(2;), and humidified. During these experiments images were taken of each cluster every 3 minutes for 400 minutes. Over a course of 400 minutes, we observed the dissipation of mitochondrial membrane potential in NIT-1 cell clusters where AI4 T cells were attached. In the simultaneous control experiment where NIT-1 cells were co-cultured with MHC mis-matched human lymphocyte Jurkat cells, mitochondrial membrane potential remained intact. This technique can be used to observe real-time changes in mitochondrial membrane potential in cells under attack of cytotoxic lymphocytes, cytokines, or other cytotoxic reagents.

Intron polymorphism in the KIAA0350 gene is reproducibly associated with susceptibility to type 1 diabetes (T1D) in the Han Chinese population

OBJECTIVE

Three independent genome-wide association studies in white populations have reported that single nucleotide polymorphisms (SNPs) in the KIAA0350 gene are associated with susceptibility to type 1 diabetes (T1D). The gene product of KIAA0350 is predicted to be a sugar binding C-type lectin. In the present study, we investigated whether SNPs in this gene were associated with T1D in the Han Chinese population.

DESIGN AND METHODS

In this case-controlled association study, a total of 205 T1D patients and 422 non-diabetic subjects of the Han Chinese population were enrolled. Two SNPs, namely, rs17802927 and rs725613, in the KIAA0350 gene were genotyped using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) protocol.

RESULTS

The intron SNP rs725613 was strongly associated with T1D in the Han Chinese population [P = 0.00007, odds ratio (OR) = 0.527, 95% confidence interval (CI) = 0.383-0.726], and the frequencies of its genotypes in the T1D group significantly differed from those in the control group (P = 0.0001).

CONCLUSION

The intron polymorphism rs725613 in the KIAA0350 gene is associated with susceptibility to T1D, and this association is not race specific.

Apolipoprotein M promoter polymorphisms alter promoter activity and confer the susceptibility to the development of type 1 diabetes

OBJECTIVES

Apolipoprotein M plays an important role in the formation of prebeta-HDL and cholesterol efflux to HDL. In the present study, we investigate the potential association between the ApoM promoter polymorphisms and type 1 diabetes.

DESIGN AND METHODS

The study was conducted in Peking Union Medical College, Beijing, China and Karolinska Institutet, Stockholm, Sweden. Two populations, including 493 Han Chinese subjects (177 T1D patients/316 controls) and 225 Swedish (124/101), are enrolled in the present study. Three single nucleotide polymorphisms (SNP) C-1065A, T-855C and T-778C in the promoter region of the ApoM gene are genotyped using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) protocol. Promoter activity was measured by reporter gene assay.

RESULTS

SNP T-778C was strongly associated with T1D in both Han Chinese (p=0.002, OR=2.188, CI 95%=1.338-3.581) and Swedish (p=0.021, OR=2.865, CI 95%=1.128-7.278) populations. The luciferase activity of -778C promoter was 1.41 times as high as that of -778T promoter (9.90+/-1.92 vs. 7.04+/-0.76, p=0.001).

CONCLUSIONS

Allele C of SNP T-778C may increase promoter activity and confer the risk susceptibility to the development of T1D.

The Immunotherapeutic Effects of Astragalus Polysaccharide in Type 1 Diabetic Mice

The present study investigated whether Astragalus polysaccharide (APS) possessed immunotherapeutic effects on type 1 diabetes mellitus. Diabetic mice induced by multiple low dose streptozotocin (MLD-STZ) were administered either APS (100, 200, 400 mg/kg body weight) or saline intraperitoneally daily, and sacrificed after 15 or 30 d of treatment. Meanwhile normal mice not treated with STZ nor with APS were offered into non-diabetic group. Blood glucose and serum insulin levels were measured, histologic and morphometric analyses of the pancreas were performed to determine the effect of APS on pancreatic islets. Further investigations on immune changes in spleens were tested by ELISA, semi-quantitative RT-PCR and Western blot. Downregulated blood glucose level, upregulated serum insulin concentration, increased beta cell mass, decreased apoptotic beta cell percentage, downregulation of Th1/Th2 cytokine ratio and upregulation of peroxisome proliferator-activated receptor gamma (PPARgamma) gene expression in spleens were significantly time- and dose-dependent on APS treatment, when compared to saline controls. These results show that APS seems to be helpful to attenuate insulitis and preserve beta cells from apoptosis, but it can't entirely rescue type 1 diabetes mellitus. APS ameliorates both the clinical and histological parameters of the MLD-STZ induced diabetic mice in a long-lasting fashion, most likely through immunoregulatory actions on Th1/Th2 cytokine ratio, strongly associated with PPARgamma gene expression in spleens.

Treatment of the patient with diabetes: importance of maintaining target HbA(1c) levels

OBJECTIVE

To review clinical trial evidence supporting treatment of patients to a near-normal HbA(1c) target level and outline therapeutic strategies that optimize glycemic control.

RESEARCH DESIGN AND METHODS

The current MEDLINE database and bibliographies were searched for literature relevant to diabetic complications, glycemic control, and the intensive management of diabetes mellitus.

RESULTS

Two randomized trials, the Diabetes Control and Complications Trial and the UK Prospective Diabetes Study (UKPDS), provided evidence that intensive glycemic control obtained with either intensive insulin or oral therapy effectively slowed the onset and progression of diabetic retinopathy, nephropathy, and neuropathy in patients with type 1 and type 2 diabetes. An epidemiologic analysis of the UKPDS results showed a significant correlation between glycemic control and microvascular and cardiovascular disease risk and mortality rates.

CONCLUSIONS

The results of clinical trials confirm that stringent levels of glycemic control can be attained through the use of intensive multiple-injection insulin regimens (administration of insulin 3 or more times daily by injection or an external pump with dosage adjustments as needed), oral monotherapy or combination therapy, or a combination of insulin and oral therapy. The expanded choices for oral agents and the availability of insulin analogs now provide physicians with the tools to tailor therapy to prevent or delay the devastating complications of diabetes. Indeed, newer insulin analogs, both short-acting (insulin lispro, insulin aspart) and long-acting (insulin glargine), are an important part of a treatment strategy to circumvent diabetes complications and overcome the shortcomings of conventional insulin preparations.