MiR-375 and miR-200c as predictive biomarkers of islet isolation and transplantation in total pancreatectomy with islet autotransplantation

Beta-cell death and dysfunction drives hyperglycaemia in organ donors

BACKGROUND

Donor hyperglycaemia following brain death has been attributed to reversible insulin resistance. However, our islet and pancreas transplant data suggest that other mechanisms may be predominant. We aimed to determine the relationships between donor insulin use and markers of beta-cell death and beta-cell function in pancreas donors after brain death.

METHODS

In pancreas donors after brain death, we compared clinical and biochemical data in 'insulin-treated' and 'not insulin-treated donors' (IT vs. not-IT). We measured plasma glucose, C-peptide and levels of circulating unmethylated insulin gene promoter cell-free DNA (INS-cfDNA) and microRNA-375 (miR-375), as measures of beta-cell death. Relationships between markers of beta-cell death and islet isolation outcomes and post-transplant function were also evaluated.

RESULTS

Of 92 pancreas donors, 40 (43%) required insulin. Glycaemic control and beta-cell function were significantly poorer in IT donors versus not-IT donors [median (IQR) peak glucose: 8 (7-11) vs. 6 (6-8) mmol/L, p = .016; C-peptide: 3280 (3159-3386) vs. 3195 (2868-3386) pmol/L, p = .046]. IT donors had significantly higher levels of INS-cfDNA [35 (18-52) vs. 30 (8-51) copies/ml, p = .035] and miR-375 [1.050 (0.19-1.95) vs. 0.73 (0.32-1.10) copies/nl, p = .05]. Circulating donor miR-375 was highly predictive of recipient islet graft failure at 3 months [adjusted receiver operator curve (SE) = 0.813 (0.149)].

CONCLUSIONS

In pancreas donors, hyperglycaemia requiring IT is strongly associated with beta-cell death. This provides an explanation for the relationship of donor IT with post-transplant beta-cell dysfunction in transplant recipients.

Clinical and biological significance of circulating miRNAs in chronic pancreatitis patients undergoing total pancreatectomy with islet autotransplantation

BACKGROUND

Specific microRNAs (miRNAs) were elevated in chronic pancreatitis (CP) patients during islet infusion after total pancreatectomy (TPIAT). We aimed to identify circulating miRNA signatures of pancreatic damage, predict miRNA-mRNA networks to identify potential links to CP pathogenesis and identify islet isolation and transplantation functional outcomes.

METHODS

Small RNA sequencing was performed to identify distinct circulating miRNA signatures in CP. Plasma miRNAs were measured using miRCURY LNA SYBR green quantitative real-time polymerase chain reaction assays. Correlation analyses were performed using R software. The miRNA target and disease interactions were determined using miRNet and the miRNA enrichment and annotation tool.

RESULTS

Alterations were found in circulating miRNAs in CP patients compared to healthy controls. Further studies were conducted on 12 circulating miRNAs enriched in the pancreas, other tissues and other diseases including cancer and fibrosis. Approximately 2888 mRNAs in the pancreas were their targets, demonstrating interactions with 76 small molecules. Three miRNAs exhibited interactions with morphine and five exhibited interactions with glucose. The miRNA panel targeted 22 genes associated with pancreatitis. The islet-specific, acinar cell-specific and liver-specific miRNAs were elevated at 6 h after islet infusion and returned to baseline levels 3 months after TPIAT. Circulating levels of miRNAs returned to pre-transplant levels 1-year post-transplant. Circulating miRNAs measured before and 6 h after islet infusion were directly or inversely associated with metabolic outcomes at 3 and 6 months post-transplant.

CONCLUSIONS

miRNAs may contribute to CP pathogenesis, and elevated circulating levels may be specific to pancreatic inflammation and fibrosis, warranting further investigation.

Assessment of Culture/Preservation Conditions of Human Islets for Transplantation

Islet culture before clinical transplantation has been adopted by various centers, but its effect on the survival and function of islets relative to the culture conditions and media needs further assessment. Human islets were cultured or preserved under four different conditions and three media options. Parameters such as recovery, viability, function, islet damage, and gene expressions for markers of hypoxia, and inflammation were assessed after 48-h culture or preservation. Preservation of islets was performed at 4°C in Connaught’s Medical Research Lab (CMRL) and University of Wisconsin (UW) media. Islets were cultured at 22°C, 37°C, and 37°C–22°C in CMRL and PRODO culture media. Islets preserved in UW solution had visually good morphology and exhibited higher recovery with less islet damage compared with the rest of the groups, whereas islets preserved in CMRL at 4°C resulted in poor morphology, recovery, viability, and function compared with the rest of the treatment conditions. Culture at 22°C and 37°C demonstrated an increase in the expression of inflammatory and hypoxia-related genes. In conclusion, islets preserved at 4°C in UW solution showed the best overall outcomes after 48 h compared with islets cultured at 22°C, 37°C, or 37°C–22°C in PRODO. Advancement in islet culture media is warranted to reduce inflammatory gene activation and improve recovery of islets for transplantation.

Outcomes of Islet Autotransplantation in Chronic Pancreatitis Patients with Complete Acinar Atrophy

Total pancreatectomy with islet autotransplantation (TPIAT) is a promising treatment for refractory chronic pancreatitis (CP). Pathological features of CP include progressive fibrosis in pancreas parenchyma, atrophy, and/or ductal occlusion. Complete acinar atrophy (CAA) caused by chronic fibrosis and necroinflammation results in exocrine sufficiency and may influence islet isolation characteristics during TPIAT. In this analysis of patients who underwent TPIAT at our center, we compared transplant outcomes among those with CAA (n = 5) vs non-acinar atrophy (NAA; matching controls, n = 36). Data were analyzed using one-way analysis of variance with Bonferroni post hoc test or Student's t test. Pancreas digestion was longer in CAA than in NAA cases (18.6 vs 14.6 min) despite a lower pancreas weight (55.2 vs 91.2 g). Obtained tissue volume was 1.0 ml in the CAA group and 12.1 ml in the NAA group. Both groups had similar islet viability (96%) and islet dose (CAA, 3,391 IEQ/kg; NAA, 4141.1 IEQ/kg). During islet infusion, serum cytokine (IL-6, IL-8, and MCP-1) levels and plasma hsa-miR-375 levels were lower in the CAA group than in the NAA group, but not significantly. Serum tumor necrosis factor α levels at 3 h after infusion were significantly higher in CAA group than in NAA group. After TPIAT, the metabolic outcomes of the CAA group were comparable with that of the NAA group. Narcotics usage decreased significantly over 24 months in both groups, with the CAA group reporting being pain free at 12 months. Complete atrophy of acinar cells of pancreas did not significantly impact islet yield or endocrine function after TPIAT.

Circulating miRNA in Patients Undergoing Total Pancreatectomy and Islet Autotransplantation

Circulating microRNAs (miRNAs) can be biomarkers for diagnosis and progression of several pathophysiological conditions. In a cohort undergoing total pancreatectomy with islet autotransplantation (TPIAT) from the multicenter Prospective Observational Study of TPIAT (POST), we investigated associations between a panel of circulating miRNAs (hsa-miR-375, hsa-miR-29b-3p, hsa-miR-148a-3p, hsa-miR-216a-5p, hsa-miR-320d, hsa-miR-200c, hsa-miR-125b, hsa-miR-7-5p, hsa-miR-221-3p, hsa-miR-122-5p) and patient, disease and islet-isolation characteristics. Plasma samples (n = 139) were collected before TPIAT and miRNA levels were measured by RTPCR. Disease duration, prior surgery, and pre-surgical diabetes were not associated with circulating miRNAs. Levels of hsa-miR-29b-3p (P = 0.03), hsa-miR-148a-3p (P = 0.04) and hsa-miR-221-3p (P = 0.01) were lower in those with genetic risk factors. Levels of hsa-miR-148a-3p (P = 0.04) and hsa-miR-7-5p (P = 0.04) were elevated in toxic/metabolic disease. Participants with exocrine insufficiency had lower hsa-miR-29b-3p, hsa-miR-148a-3p, hsa-miR-320d, hsa-miR-221-3p (P < 0.01) and hsa-miR-375, hsa-miR-200c-3p, and hsa-miR-125b-5p (P < 0.05). Four miRNAs were associated with fasting C-peptide before TPIAT (hsa-miR-29b-3p, r = 0.18; hsa-miR-148a-3p, r = 0.21; hsa-miR-320d, r = 0.19; and hsa-miR-221-3p, r = 0.21; all P < 0.05), while hsa-miR-29b-3p was inversely associated with post-isolation islet equivalents/kg and islet number/kg (r = −0.20, P = 0.02). Also, hsa-miR-200c (r = 0.18, P = 0.03) and hsa-miR-221-3p (r = 0.19, P = 0.03) were associated with islet graft tissue volume. Further investigation is needed to determine the predictive potential of these miRNAs for assessing islet autotransplant outcomes.

miR-375 Promotes Pancreatic Differentiation In Vitro by Affecting Different Target Genes at Different Stages

Human embryonic stem cells (hESCs) possess the ability to differentiate into insulin-producing cells (IPCs), which can be used to treat type I diabetes. miR-375 is an essential transcriptional regulator in the development and maturation of the pancreas. In this study, we optimized a protocol to differentiate hESCs into IPCs and successfully obtained IPCs. Then, we performed overexpression and inhibition experiments of miR-375 on cells at different stages of differentiation and performed RNA-seq. The results showed that the expression of miR-375 fluctuated during hESC differentiation and was affected by miR-375 mimics and inhibitors. miR-375 influences global gene expression and the target genes of miR-375. The overexpression of miR-375 can cause changes in multiple signaling pathways during pancreatic development. miR-375 is a major participant in the differentiation of pancreatic β-cells through different target genes at different stages. This study provides new ideas for further investigation of how microRNAs affect cell fate and gene transcription.

Biomarkers of Chronic Pancreatitis: A systematic literature review

BACKGROUND

Chronic pancreatitis (CP) does not have diagnostic or prognostic biomarkers. CP is the end stage of a progressive inflammatory syndrome that is diagnosed at late stages by morphologic features. To diagnose earlier stages of the disease, a new mechanistic definition was established based on identifying underlying pathogenic processes and biomarker evidence of disease activity and stage. Although multiple risk factors are known, the corresponding biomarkers needed to make a highly accurate diagnosis of earlier disease stages have not been established. The goal of this study is to systematically analyze the literature to identify the most likely candidates for development into biomarkers of CP.

METHODS

We conducted a systematic review of candidate analytes from easily accessible biological fluids and identified 67 studies that compared CP to nonpancreatic-disease controls. We then ranked candidate biomarkers for sensitivity and specificity by area under the receiver operator curves (AUROCs).

RESULTS

Five biomarkers had a large effect size (an AUROC > 0.96), whereas 30 biomarkers had a moderate effect size (an AUROC between 0.96 and 0.83) for distinguishing CP cases from controls or other diseases. However, the studies reviewed had marked variability in design, enrollment criteria, and biospecimen sample handling and collection.

CONCLUSIONS

Several biomarkers have the potential for evaluation in prospective cohort studies and should be correlated with risk factors, clinical features, imaging studies and outcomes. The Consortium for the Study of Chronic Pancreatitis, Diabetes and Pancreas Cancer provides recommendations for avoiding design biases and heterogeneity in sample collection and handling in future studies.

Building Biomimetic Potency Tests for Islet Transplantation

Diabetes is a disease of insulin insufficiency, requiring many to rely on exogenous insulin with constant monitoring to avoid a fatal outcome. Islet transplantation is a recent therapy that can provide insulin independence, but the procedure is still limited by both the availability of human islets and reliable tests to assess their function. While stem cell technologies are poised to fill the shortage of transplantable cells, better methods are still needed for predicting transplantation outcome. To ensure islet quality, we propose that the next generation of islet potency tests should be biomimetic systems that match glucose stimulation dynamics and cell microenvironmental preferences and rapidly assess conditional and continuous insulin secretion with minimal manual handing. Here, we review the current approaches for islet potency testing and outline technologies and methods that can be used to arrive at a more predictive potency test that tracks islet secretory capacity in a relevant context. With the development of potency tests that can report on islet secretion dynamics in a context relevant to their intended function, islet transplantation can expand into a more widely accessible and reliable treatment option for individuals with diabetes.

Assessment of plasma microvesicles to monitor pancreatic islet graft dysfunction: Beta cell- and leukocyte-derived microvesicles as specific features in a pilot longitudinal study

Markers of early pancreatic islet graft dysfunction and its causes are lacking. We monitored 19 type 1 diabetes islet-transplanted patients for up to 36 months following last islet injection. Patients were categorized as Partial (PS) or complete (S) Success, or Graft Failure (F), using the β-score as an indicator of graft function. F was the subset reference of maximum worsened graft outcome. To identify the immune, pancreatic, and liver contribution to the graft dysfunction, the cell origin and concentration of circulating microvesicles (MVs) were assessed, including MVs from insulin-secreting β-cells typified by polysialic acid of neural cell adhesion molecule (PSA-NCAM), and data were compared with values of the β-score. Similar ranges of PSA-NCAM⁺ -MVs were found in healthy volunteers and S patients, indicating minimal cell damage. In PS, a 2-fold elevation in PSA-NCAM⁺ -MVs preceded each β-score drop along with a concomitant rise in insulin needs, suggesting β-cell damage or altered function. Significant elevation of liver asialoglycoprotein receptor (ASGPR)⁺ -MVs, endothelial CD105⁺ -MVs, neutrophil CD66b⁺ -MVs, monocyte CD 14⁺ -MVs, and T4 lymphocyte CD4⁺ -MVs occurred before each β-score drop, CD8⁺ -MVs increased only in F, and B lymphocyte CD19⁺ -MVs remained undetectable. In conclusion, PSA-NCAM⁺ -MVs are noninvasive early markers of transplant dysfunction, while ASGPR⁺ -MVs signal host tissue remodeling. Leukocyte MVs could identify the cause of graft dysfunction.

Differential expression and release of exosomal miRNAs by human islets under inflammatory and hypoxic stress

AIMS/HYPOTHESIS

Pancreatic islets produce non-coding microRNAs (miRNAs) that regulate islet cell function and survival. Our earlier investigations revealed that human islets undergo significant damage due to various types of stresses following transplantation and release miRNAs. Here, we sought to identify and validate exosomal miRNAs (exo-miRNAs) produced by human islets under conditions of cellular stress, preceding loss of cell function and death. We also aimed to identify islet stress signalling pathways targeted by exo-miRNAs to elucidate potential regulatory roles in islet cell stress.

METHODS

Human islets were subjected to proinflammatory cytokine and hypoxic cell stress and miRNA from exosomes was isolated for RNA sequencing and analysis. Stress-induced exo-miRNAs were evaluated for kinetics of expression and release by intact islets for up to 48 h exposure to cytokines and hypoxia. A subset of stress-induced exo-miRNAs were assessed for recovery and detection as biomarkers of islet cell stress in a diabetic nude mouse xenotransplant model and in patients undergoing total pancreatectomy with islet auto-transplantation (TPIAT). Genes and signalling pathways targeted by stress-induced exo-miRNAs were identified by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and direct interactions of miRNAs with downstream signalling targets were validated in human islet cells using the miRNA Tests for Read Analysis and Prediction (MirTrap) system.

RESULTS

Global exo-miRNA sequencing revealed that 879 miRNA species were released from human islets and 190 islet exo-miRNAs were differentially expressed in response to proinflammatory cytokines, hypoxia or both. Release of exo-miRNAs hsa-miR-29b-3p and hsa-miR-216a-5p was detected within 6 h of exposure to cytokines and hypoxia. The remaining subset of stress-induced exo-miRNAs, including hsa-miR-148a-3p and islet cell damage marker hsa-miR-375, showed delayed release at 24-48 h, correlating with apoptosis and cell death. Stress and damage exo-miRNAs were significantly elevated in the circulation in human-to-mouse xenotransplant models and in human transplant recipients. Elevated blood exo-miRNAs negatively correlated with post-transplant islet function based on comparisons of stress and damage exo-miRNA indices with Secretory Unit of Islet Transplant Objects (SUITO) indices. KEGG analysis and further validation of exo-miRNA targets by MirTrap analysis revealed significant enrichment of islet mRNAs involved in phosphoinositide 3-kinase/Akt and mitogen-activated protein kinase signalling pathways.

CONCLUSIONS/INTERPRETATION

The study identifies exo-miRNAs differentially expressed and released by islets in response to damage and stress. These exo-miRNAs could serve as potential biomarkers for assessing islet damage and predicting outcomes in islet transplantation. Notably, exo-miRNAs 29b-3p and 216a-5p could be detected in islets prior to damage-released miRNAs and indicators of cellular apoptosis and death. Thus, these stress-induced exo-miRNAs may have potential diagnostic value for detecting early islet stress prior to progressive loss of islet cell mass and function. Further investigations are warranted to investigate the utility of these exo-miRNAs as early indicators of islet cell stress during prediabetic conditions.

Geographical variance in reporting of elective surgery for chronic pancreatitis

The selection of optimum surgical procedure from the range of reported operations for chronic pancreatitis (CP) can be difficult. The aim of this study is to explore geographical variation in reporting of elective surgery for CP. A systematic search of the literature was performed using the Scopus database for reports of five selected procedures for CP: duodenum-preserving pancreatic head resection, total pancreatectomy with islet autotransplantation (TPIAT), Frey pancreaticojejunostomy, thoracoscopic splanchnotomy and the Izbicki V-shaped resection. The keyword and MESH heading 'chronic pancreatitis' was used. Overall, 144 papers met inclusion criteria and were utilized for data extraction. There were 33 reports of duodenum-preserving pancreatic head resection. Twenty-one (64%) were from Germany. There were 60 reports of TPIAT, 53 (88%) from the USA. There are only two reports of TPIAT from outwith the USA and UK. The 34 reports of the Frey pancreaticojejunostomy originate from 12 countries. There were 20 reports of thoracoscopic splanchnotomy originating from nine countries. All three reports of the Izbicki 'V' procedure are from Germany. There is geographical variation in reporting of surgery for CP. There is a need for greater standardization in the selection and reporting of surgery for patients with painful CP.

Assessment of simple indices based on a single fasting blood sample as a tool to estimate beta-cell function after total pancreatectomy with islet autotransplantation - a prospective study

We investigated six indices based on a single fasting blood sample for evaluation of the beta-cell function after total pancreatectomy with islet autotransplantation (TP-IAT). The Secretory Unit of Islet Transplant Objects (SUITO), transplant estimated function (TEF), homeostasis model assessment (HOMA-2B%), C-peptide/glucose ratio (CP/G), C-peptide/glucose creatinine ratio (CP/GCr) and BETA-2 score were compared against a 90-min serum glucose level, weighted mean C-peptide in mixed meal tolerance test (MMTT), beta score and the Igls score adjusted for islet function in the setting of IAT. We analyzed values from 32 MMTTs in 15 patients after TP-IAT with a follow-up of up to 3 years. Four (27%) individuals had discontinued insulin completely prior to day 75, while 6 out of 12 patients (50%) did not require insulin support at 1-year follow-up with HbA1c 6.0% (5.5-6.8). BETA-2 was the most consistent among indices strongly correlating with all reference measures of beta-cell function (r = 0.62-0.68). In addition, it identified insulin independence (cut-off = 16.2) and optimal/good versus marginal islet function in the Igls score well, with AUROC of 0.85 and 0.96, respectively. Based on a single fasting blood sample, BETA-2 score has the most reliable discriminant value for the assessment of graft function in patients undergoing TP-IAT.

Is miRNA-375 a promising biomarker for early detection and monitoring of patients with type 2 diabetes?

miRNAs are small, non-coding RNAs, functioning as negative suppressors of target gene expression. A significant proportion of the transcriptome is subject to miRNA modulation. A single miRNA determines the expression of hundreds of genes, while miRNAs are relatively stable in biological fluids. Thus, they have attracted scientific interest regarding their use as biomarkers for several diseases. miRNA-375 mainly influences β-cell function and insulin secretion. Several studies, primarily experimental, have assessed its role as a biomarker in type 2 diabetes, while recently obtained human evidence supports this potential role. Besides its diagnostic potential, miRNA-375 may also have therapeutic implications. In view of the growing epidemic of type 2 diabetes, there is an unmet need for identification of biomarkers for early recognition and monitoring of these patients. Long-term, prospective human studies are required to elucidate whether miRNA-375 can evolve as a key player in diagnosis and prognosis of type 2 diabetes.

Biomarkers in Islet Cell Transplantation for Type 1 Diabetes

PURPOSE OF REVIEW

Islet transplantation, an important approach to achieve insulin independence for individuals with type 1 diabetes, is limited by the lack of accurate biomarkers to track beta-cell death post islet infusion. In this review, we will discuss existing and recently described biomarkers.

RECENT FINDINGS

As beta cells are killed by the immune system, fragments of beta cell-specific cell-free DNA and proteins are released into the periphery. Several different strategies to identify these fragments have been described. Some circulating, non-coding microRNAs, particularly miRNA-375 are also showing potential to reflect the rate of beta cell loss post-clinical islet transplantation. Recent advances in identifying accurate beta cell-specific biomarkers such as differentially methylated insulin cell-free DNA and circulating miRNA-375 may help predict clinical outcomes. More studies are required to examine the robustness of these biomarkers to detect chronic beta-cell loss in islet transplantation recipients.

Total pancreatectomy and islet autotransplantion for chronic and recurrent acute pancreatitis

PURPOSE OF REVIEW

We reviewed the current state of total pancreatectomy with islet autotransplantation (TPIAT) for chronic pancreatitis and recurrent acute pancreatitis (RAP).

RECENT FINDINGS

An increasing number of centers in the United States and internationally are performing TPIAT. In selected cases, TPIAT may be performed partially or entirely laparoscopically. Islet isolation is usually performed at the same center as the total pancreatectomy surgery, but new data suggest that diabetes outcomes may be nearly as good when a remote center is used for islet isolation. Ongoing clinical research is focused on patient and disease factors that predict success or failure to respond to TPIAT. Causes of persistent abdominal pain after TPIAT may include gastrointestinal dysmotility and central sensitization to pain. Several clinical trials are underway with anti-inflammatory or other islet protective strategies to better protect islets at the time of infusion and thereby improve the diabetes results of the procedure.

SUMMARY

In summary, there is an increasing body of literature emerging from multiple centers highlighting the benefits and persistent challenges of TPIAT for chronic pancreatitis and RAP. Ongoing study will be critical to optimizing the success of this procedure.

Islet damage during isolation as assessed by miRNAs and the correlation of miRNA levels with posttransplantation outcome in islet autotransplantation

High-quality pancreatic islets are essential for better posttransplantation endocrine function in total pancreatectomy with islet autotransplantation (TPIAT), yet stress during the isolation process affects quality and yield. We analyzed islet-enriched microRNAs (miRNAs) -375 and -200c released during isolation to assess damage and correlated the data with posttransplantation endocrine function. The absolute concentration of miR-375, miR-200c, and C-peptide was measured in various islet isolation steps, including digestion, dilution, recombination, purification, and bagging, in 12 cases of TPIAT. Posttransplantation glycemic control was monitored through C-peptide, hemoglobin A_1c , insulin requirement, and SUITO index. The amount of miR-375 released was significantly higher during enzymatic digestion followed by the islet bagging (P < .001). Mir-200c mirrored these changes, albeit at lower concentrations. In contrast, the C-peptide amount was significantly higher in the purification and bagging steps (P < .001). Lower amounts of miR-375 were associated with a lower 6-month insulin requirement (P = .01) and lower hemoglobin A_1c (P = .04). Measurement of the absolute quantity of miRNA-375 and -200c released during islet isolation is a useful tool to assess islet damage. The quantity of released miRNA is indicative of posttransplantation endocrine function in TPIAT patients.

Identification and Characterization of microRNAs Associated With Human β-Cell Loss in a Mouse Model

Currently there is no effective approach for monitoring early β-cell loss during islet graft rejection following human islet transplantation (HIT). Due to ethical and technical constraints, it is difficult to directly study biomarkers of islet destruction in humans. Here, we established a humanized mouse model with induced human β-cell death using adoptive lymphocyte transfer (ALT). Human islet grafts of ALT-treated mice had perigraft lymphocyte infiltration, fewer insulin⁺ β cells, and increased β-cell apoptosis. Islet-specific miR-375 was used to validate our model, and expression of miR-375 was significantly decreased in the grafts and increased in the circulation of ALT-treated mice before hyperglycemia. A NanoString expression assay was further used to profile 800 human miRNAs in the human islet grafts, and the results were validated using quantitative real-time polymerase chain reaction. We found that miR-4454 and miR-199a-5p were decreased in the human islet grafts following ALT and increased in the circulation prior to hyperglycemia. These data demonstrate that our in vivo model of induced human β-cell destruction is a robust method for identifying and characterizing circulating biomarkers, and suggest that miR-4454 and miR-199a-5p can serve as novel biomarkers associated with early human β-cell loss following HIT.