Increased Expression of Viral Sensor MDA5 in Pancreatic Islets and in Hormone-Negative Endocrine Cells in Recent Onset Type 1 Diabetic Donors.

The interaction between genetic and environmental factors determines the development of type 1 diabetes (T1D). Some viruses are capable of infecting and damaging pancreatic ß-cells, whose antiviral response could be modulated by specific viral RNA receptors and sensors such as melanoma differentiation associated gene 5 (MDA5), encoded by the IFIH1 gene. MDA5 has been shown to be involved in pro-inflammatory and immunoregulatory outcomes, thus determining the response of pancreatic islets to viral infections. Although the function of MDA5 has been previously well explored, a detailed immunohistochemical characterization of MDA5 in pancreatic tissues of nondiabetic and T1D donors is still missing. In the present study, we used multiplex immunofluorescence imaging analysis to characterize MDA5 expression and distribution in pancreatic tissues obtained from 22 organ donors (10 nondiabetic autoantibody-negative, 2 nondiabetic autoantibody-positive, 8 recent-onset, and 2 long-standing T1D). In nondiabetic control donors, MDA5 was expressed both in α- and ß-cells. The colocalization rate imaging analysis showed that MDA5 was preferentially expressed in α-cells. In T1D donors, we observed an increased colocalization rate of MDA5-glucagon with respect to MDA5-insulin in comparison to nondiabetic controls; such increase was more pronounced in recent-onset with respect to long-standing T1D donors. Of note, an increased colocalization rate of MDA5-glucagon was found in insulin-deficient-islets (IDIs) with respect to insulin-containing-islets (ICIs). Strikingly, we detected the presence of MDA5-positive/hormone-negative endocrine islet-like clusters in T1D donors, presumably due to dedifferentiation or neogenesis phenomena. These clusters were identified exclusively in donors with recent disease onset and not in autoantibody-positive nondiabetic donors or donors with long-standing T1D. In conclusion, we showed that MDA5 is preferentially expressed in α-cells, and its expression is increased in recent-onset T1D donors. Finally, we observed that MDA5 may also characterize the phenotype of dedifferentiated or newly forming islet cells, thus opening to novel roles for MDA5 in pancreatic endocrine cells.

MicroRNA Expression in the Aqueous Humor of Patients with Diabetic Macular Edema.

We identified and compared secreted microRNA (miRNA) expression in aqueous humor (AH) and plasma samples among patients with: type 2 diabetes mellitus (T2D) complicated by non-proliferative diabetic retinopathy (DR) associated with diabetic macular edema (DME) (DME group: 12 patients); T2D patients without DR (D group: 8 patients); and non-diabetic patients (CTR group: 10 patients). Individual patient AH samples from five subjects in each group were profiled on TaqMan Low Density MicroRNA Array Cards. Differentially expressed miRNAs identified from profiling were then validated in single assay for all subjects. The miRNAs validated in AH were then evaluated in single assay in plasma. Gene Ontology (GO) analysis was conducted. From AH profiling, 119 mature miRNAs were detected: 86 in the DME group, 113 in the D group and 107 in the CTR group. miRNA underexpression in the DME group was confirmed in single assay for let-7c-5p, miR-200b-3p, miR-199a-3p and miR-365-3p. Of these four, miR-199a-3p and miR-365-3p were downregulated also in the plasma of the DME group. GO highlighted 54 validated target genes of miR-199a-3p, miR-200b-3p and miR-365-3p potentially implied in DME pathogenesis. Although more studies are needed, miR-200b-3p, let-7c-5p, miR-365-3p and miR-199a-3p represent interesting molecules in the study of DME pathogenesis.

Prevention and treatment of autoimmune diseases with plant virus nanoparticles.

Plant viruses are natural, self-assembling nanostructures with versatile and genetically programmable shells, making them useful in diverse applications ranging from the development of new materials to diagnostics and therapeutics. Here, we describe the design and synthesis of plant virus nanoparticles displaying peptides associated with two different autoimmune diseases. Using animal models, we show that the recombinant nanoparticles can prevent autoimmune diabetes and ameliorate rheumatoid arthritis. In both cases, this effect is based on a strictly peptide-related mechanism in which the virus nanoparticle acts both as a peptide scaffold and as an adjuvant, showing an overlapping mechanism of action. This successful preclinical testing could pave the way for the development of plant viruses for the clinical treatment of human autoimmune diseases.

Unexpected subcellular distribution of a specific isoform of the Coxsackie and adenovirus receptor, CAR-SIV, in human pancreatic beta cells.

AIMS/HYPOTHESIS: The Coxsackie and adenovirus receptor (CAR) is a transmembrane cell-adhesion protein that serves as an entry receptor for enteroviruses and may be essential for their ability to infect cells. Since enteroviral infection of beta cells has been implicated as a factor that could contribute to the development of type 1 diabetes, it is often assumed that CAR is displayed on the surface of human beta cells. However, CAR exists as multiple isoforms and it is not known whether all isoforms subserve similar physiological functions. In the present study, we have determined the profile of CAR isoforms present in human beta cells and monitored the subcellular localisation of the principal isoform within the cells. METHODS: Formalin-fixed, paraffin-embedded pancreatic sections from non-diabetic individuals and those with type 1 diabetes were studied. Immunohistochemistry, confocal immunofluorescence, electron microscopy and western blotting with isoform-specific antisera were employed to examine the expression and cellular localisation of the five known CAR isoforms. Isoform-specific qRT-PCR and RNA sequencing (RNAseq) were performed on RNA extracted from isolated human islets. RESULTS: An isoform of CAR with a terminal SIV motif and a unique PDZ-binding domain was expressed at high levels in human beta cells at the protein level. A second isoform, CAR-TVV, was also present. Both forms were readily detected by qRT-PCR and RNAseq analysis in isolated human islets. Immunocytochemical studies indicated that CAR-SIV was the principal isoform in islets and was localised mainly within the cytoplasm of beta cells, rather than at the plasma membrane. Within the cells it displayed a punctate pattern of immunolabelling, consistent with its retention within a specific membrane-bound compartment. Co-immunofluorescence analysis revealed significant co-localisation of CAR-SIV with zinc transporter protein 8 (ZnT8), prohormone convertase 1/3 (PC1/3) and insulin, but not proinsulin. This suggests that CAR-SIV may be resident mainly in the membranes of insulin secretory granules. Immunogold labelling and electron microscopic analysis confirmed that CAR-SIV was localised to dense-core (insulin) secretory granules in human islets, whereas no immunolabelling of the protein was detected on the secretory granules of adjacent exocrine cells. Importantly, CAR-SIV was also found to co-localise with protein interacting with C-kinase 1 (PICK1), a protein recently demonstrated to play a role in insulin granule maturation and trafficking. CONCLUSIONS/INTERPRETATION: The SIV isoform of CAR is abundant in human beta cells and is localised mainly to insulin secretory granules, implying that it may be involved in granule trafficking and maturation. We propose that this subcellular localisation of CAR-SIV contributes to the unique sensitivity of human beta cells to enteroviral infection.

Conventional and Neo-antigenic Peptides Presented by ß Cells Are Targeted by Circulating Naïve CD8+ T Cells in Type 1 Diabetic and Healthy Donors.

Although CD8+ T-cell-mediated autoimmune ß cell destruction occurs in type 1 diabetes (T1D), the target epitopes processed and presented by ß cells are unknown. To identify them, we combined peptidomics and transcriptomics strategies. Inflammatory cytokines increased peptide presentation in vitro, paralleling upregulation of human leukocyte antigen (HLA) class I expression. Peptide sources featured several insulin granule proteins and all known ß cell antigens, barring islet-specific glucose-6-phosphatase catalytic subunit-related protein. Preproinsulin yielded HLA-A2-restricted epitopes previously described. Secretogranin V and its mRNA splice isoform SCG5-009, proconvertase-2, urocortin-3, the insulin gene enhancer protein ISL-1, and an islet amyloid polypeptide transpeptidation product emerged as antigens processed into HLA-A2-restricted epitopes, which, as those already described, were recognized by circulating naive CD8+ T cells in T1D and healthy donors and by pancreas-infiltrating cells in T1D donors. This peptidome opens new avenues to understand antigen processing by ß cells and for the development of T cell biomarkers and tolerogenic vaccination strategies.

Prospective Validation of ATA and ETA Sonographic Pattern Risk of Thyroid Nodules Selected for FNAC.

Context: Recently, the American Thyroid Association (ATA) and the European Thyroid Association (ETA) have proposed that thyroid ultrasound (US) should be used to stratify the risk of malignancy in thyroid nodules and to aid decision-making about whether fine-needle aspiration cytology (FNAC) is indicated. Objective: To validate and to compare the ATA and ETA US risk stratification systems of thyroid nodules in a prospective series of thyroid nodules submitted to FNAC. Setting: We prospectively evaluated 432 thyroid nodules selected for FNAC from 340 patients. Cytology reports were based on the five categories according to the criteria of the British Thyroid Association. Results: The proportion of Thy2 nodules decreased significantly, whereas the proportion of Thy4/Thy5 nodules significantly increased with increasing US risk class (P < 0.0001). The ability to identify benign and malignant nodules was similar between ATA and ETA systems. According to ATA and ETA US risk stratification systems, 23.7% and 56.0% nodules did not meet the criteria for FNAC, respectively. Considering only categories at lower risk of malignancy, the cumulative malignancy rate in these nodules was 1.2% for ATA and 1.7% for ETA US risk stratification systems. Conclusions: ETA and ATA US risk stratification systems provide effective malignancy risk stratification for thyroid nodules. In clinical practice, using this approach, we should be able to reduce the number of unnecessary FNAC without losing clinically relevant thyroid cancer.

Fighting diabetic foot ulcers-The diabetologist: A king maker of the fight.

Diabetic foot ulcer is a costly and serious complication of diabetes mellitus and is the major cause of non-traumatic limb amputations worldwide. Its development is primarily the result of diabetic neuropathy and/or peripheral arterial disease with accompanied bone abnormalities and is complicated by invasive infection. The management of this clinical condition focuses on identification of the "at-risk" foot, treatment of the ulcerated foot, and prevention of further complications. As diabetic foot ulcer represents the sum of multiple etiologies, its treatment requires a multidisciplinary team, which can result in a significant reduction in the incidence of ulcers, infections and amputations. The team should include a diabetologist, a podiatrist, an orthoptist, an educator and a plaster technician, in close collaboration with a vascular surgeon, an orthopedic/podiatric surgeon and a dermatologist. It is recommended that a diabetologist be the multidisciplinary team leader, as diabetic foot ulcer is a complication of diabetes and chronic hyperglycemia represents the main cause for its development. The appropriate composition of professionals involved in the team is institution-dependent and may vary worldwide, depending on the diabetic population. The concept of establishing a diabetic foot care team is recommended by all National and International Diabetes Scientific Societies and Associations.

Acute on chronic limb ischemia: From surgical embolectomy and thrombolysis to endovascular options.

After the invention of the balloon catheter by Fogarty in 1963, surgical thromboembolectomy was considered the gold standard treatment for many years in patients with acute lower limb ischemia (ALLI). ALLI is a dramatic event, carrying a high risk of amputation and perioperative morbidity and mortality. The evolution of endovascular technologies has resulted in a variety of therapeutic options to establish arterial patency. In the 1970s, Dotter first introduced the idea of clot lysis in the treatment of ALLI, which was modified to catheter-directed thrombolysis, and now clot aspiration techniques. Currently, the majority of ALLI (about 70%) is arterial thrombosis, which generally occurs in the setting of preexisting vascular lesion. This condition is very common in patients with diabetes. Clinical presentation in case of thrombosis on atherosclerotic stenosis (so called "acute on chronic ischemia") may be less severe, but treatment is generally more challenging than ALLI due to embolism, considering the complexity in device trackability through the diseased vessels, potential vessel injury, incomplete revascularization, and need of correction of underlying vascular lesions. Although surgery is still a treatment option, especially for ALLI, endovascular interventions have assumed a prominent role in restoring limb perfusion. In this review, the treatment options for ALLI are detailed from surgical thromboembolectomy to thrombolysis and current endovascular techniques, including mechanical fragmentation, rheolytic thrombectomy, and aspiration thrombectomy. The evolution to endovascular therapies has resulted in improved clinical outcomes and lower rates of morbidity.

Regulatory T-cells from pancreatic lymphnodes of patients with type-1 diabetes express increased levels of microRNA miR-125a-5p that limits CCR2 expression.

Autoimmune type 1 diabetes (T1D) is thought to be caused by a defective immune regulation with regulatory T (Treg) cells playing a fundamental role in this process. Tolerance mechanisms depend on tunable responses that are sensitive to minor perturbations in the expression of molecules that can be carried out by multiple epigenetic mechanisms, including regulation by microRNAs. In this study, microRNA expression profile was investigated in Treg cells isolated from peripheral blood (PB) and from pancreatic draining lymph nodes (PLN) of T1D patients and non-diabetic subjects. Among 72 microRNAs analyzed, miR-125a-5p resulted specifically hyper-expressed in Treg cells purified from PLN of T1D patients. TNFR2 and CCR2 were identified as miR-125a-5p target genes. Elevated miR-125a-5p was detected in Treg cells isolated from PLN but not from PB of donors with T1D and was associated with reduced CCR2 expression. A specific beta-cell expression of the CCR2-ligand (CCL2) was observed in the pancreata of cadaveric donors, suggesting that beta-cells are prone to attract CCR2+ Treg cells. These novel data propose a mechanism, occurring in PLNs of T1D patients, involving increased expression of miR-125a-5p on Treg cells which results into reduced expression of CCR2, thus limiting their migration and eventual function in the pancreas.

Combination therapy with metformin plus vildagliptin in type 2 diabetes mellitus.

INTRODUCTION: Type 2 diabetes mellitus (T2DM) is pathophysiologically characterized by a combination of insulin resistance and beta-cell dysfunction. Consequently, a proper treatment of such a disease should target both of these defects. Dipeptidyl peptidase-4 (DPP-4) inhibitors are among the most recent additions to the therapeutic options for T2DM and are able to increase circulating levels of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), thus stimulating glucose-dependent insulin secretion. AREAS COVERED: This paper provides an overview of the clinical results of combination therapy with metformin and the DPP-4 inhibitor vildagliptin in T2DM patients. EXPERT OPINION: Vildagliptin-metformin single-tablet combination is indicated for the treatment of T2DM patients not achieving a sufficient glycemic control at their maximally tolerated dose of metformin. Results from clinical trials provide evidence of vildagliptin efficacy administered in addition to metformin, as either first- or second-line treatment. The vildagliptin-metformin association seems to have favorable effects on beta-cell function and is characterized by good safety and tolerability profiles when compared with other antidiabetic agents. Of note, data available suggest that administration of fixed-dose combination products, together with the low incidence of adverse gastrointestinal events, may improve compliance and adherence of patients to therapy, resulting in an improved metabolic control.