Collecting high-quality pancreatic tissue for experimental study from organ donors with signs of β-cell autoimmunity

Bridging the Gap: Pancreas Tissue Slices From Organ and Tissue Donors for the Study of Diabetes Pathogenesis

Over the last two decades, increased availability of human pancreatic tissues has allowed for major expansions in our understanding of islet biology in health and disease. Indeed, studies of fixed and frozen pancreatic tissues, as well as efforts using viable isolated islets obtained from organ donors, have provided significant insights toward our understanding of diabetes. However, the procedures associated with islet isolation result in distressed cells that have been removed from any surrounding influence. The pancreas tissue slice technology was developed as an in situ approach to overcome certain limitations associated with studies on isolated islets or fixed tissue. In this Perspective, we discuss the value of this novel platform and review how pancreas tissue slices, within a short time, have been integrated in numerous studies of rodent and human islet research. We show that pancreas tissue slices allow for investigations in a less perturbed organ tissue environment, ranging from cellular processes, over peri-islet modulations, to tissue interactions. Finally, we discuss the considerations and limitations of this technology in its future applications. We believe the pancreas tissue slices will help bridge the gap between studies on isolated islets and cells to the systemic conditions by providing new insight into physiological and pathophysiological processes at the organ level.

ARTICLE HIGHLIGHTS

Human pancreas tissue slices represent a novel platform to study human islet biology in close to physiological conditions. Complementary to established technologies, such as isolated islets, single cells, and histological sections, pancreas tissue slices help bridge our understanding of islet physiology and pathophysiology from single cell to intact organ. Diverse sources of viable human pancreas tissue, each with distinct characteristics to be considered, are available to use in tissue slices for the study of diabetes pathogenesis.

Differential Detection of Encapsidated versus Unencapsidated Enterovirus RNA in Samples Containing Pancreatic Enzymes-Relevance for Diabetes Studies

Using immunohistochemistry, enterovirus capsid proteins were demonstrated in pancreatic islets of patients with type 1 diabetes. Virus proteins are mainly located in beta cells, supporting the hypothesis that enterovirus infections may contribute to the pathogenesis of type 1 diabetes. In samples of pancreatic tissue, enterovirus RNA was also detected, but in extremely small quantities and in a smaller proportion of cases compared to the enteroviral protein. Difficulties in detecting viral RNA could be due to the very small number of infected cells, the possible activity of PCR inhibitors, and the presence—during persistent infection—of the viral genome in unencapsidated forms. The aim of this study was twofold: (a) to examine if enzymes or other compounds in pancreatic tissue could affect the molecular detection of encapsidated vs. unencapsidated enterovirus forms, and (b) to compare the sensitivity of RT-PCR methods used in different laboratories. Dilutions of encapsidated and unencapsidated virus were spiked into human pancreas homogenate and analyzed by RT-PCR. Incubation of pancreatic homogenate on wet ice for 20 h did not influence the detection of encapsidated virus. In contrast, a 15-min incubation on wet ice dramatically reduced detection of unencapsidated forms of virus. PCR inhibitors could not be found in pancreatic extract. The results show that components in the pancreas homogenate may selectively affect the detection of unencapsidated forms of enterovirus. This may lead to difficulties in diagnosing persisting enterovirus infection in the pancreas of patients with type 1 diabetes.

MANF protects human pancreatic beta cells against stress-induced cell death

AIMS/HYPOTHESIS

There is a great need to identify factors that could protect pancreatic beta cells against apoptosis or stimulate their replication and thus prevent or reverse the development of diabetes. One potential candidate is mesencephalic astrocyte-derived neurotrophic factor (MANF), an endoplasmic reticulum (ER) stress inducible protein. Manf knockout mice used as a model of diabetes develop the condition because of increased apoptosis and reduced proliferation of beta cells, apparently related to ER stress. Given this novel association between MANF and beta cell death, we studied the potential of MANF to protect human beta cells against experimentally induced ER stress.

METHODS

Primary human islets were challenged with proinflammatory cytokines, with or without MANF. Cell viability was analysed and global transcriptomic analysis performed. Results were further validated using the human beta cell line EndoC-βH1.

RESULTS

There was increased expression and secretion of MANF in human beta cells in response to cytokines. Addition of recombinant human MANF reduced cytokine-induced cell death by 38% in human islets (p < 0.05). MANF knockdown in EndoC-βH1 cells led to increased ER stress after cytokine challenge. Mechanistic studies showed that the protective effect of MANF was associated with repression of the NF-κB signalling pathway and amelioration of ER stress. MANF also increased the proliferation of primary human beta cells twofold when TGF-β signalling was inhibited (p < 0.01).

CONCLUSIONS/INTERPRETATION

Our studies show that exogenous MANF protein can provide protection to human beta cells against death induced by inflammatory stress. The antiapoptotic and mitogenic properties of MANF make it a potential therapeutic agent for beta cell protection.

A novel rat CVB1-VP1 monoclonal antibody 3A6 detects a broad range of enteroviruses

Enteroviruses (EVs) are common RNA viruses that cause diseases ranging from rash to paralytic poliomyelitis. For example, EV-A and EV-C viruses cause hand-foot and mouth disease and EV-B viruses cause encephalitis and myocarditis, which can result in severe morbidity and mortality. While new vaccines and treatments for EVs are under development, methods for studying and diagnosing EV infections are still limited and therefore new diagnostic tools are required. Our aim was to produce and characterize new antibodies that work in multiple applications and detect EVs in tissues and in vitro. Rats were immunized with Coxsackievirus B1 capsid protein VP1 and hybridomas were produced. Hybridoma clones were selected based on their reactivity in different immunoassays. The most promising clone, 3A6, was characterized and it performed well in multiple techniques including ELISA, immunoelectron microscopy, immunocyto- and histochemistry and in Western blotting, detecting EVs in infected cells and tissues. It recognized several EV-Bs and also the EV-C representative Poliovirus 3, making it a broad-spectrum EV specific antibody. The 3A6 rat monoclonal antibody can help to overcome some of the challenges faced with commonly used EV antibodies: it enables simultaneous use of mouse-derived antibodies in double staining and it is useful in murine models.

Autoreactive T cells in type 1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease that causes severe loss of pancreatic β cells. Autoreactive T cells are key mediators of β cell destruction. Studies of organ donors with T1D that have examined T cells in pancreas, the diabetogenic insulitis lesion, and lymphoid tissues have revealed a broad repertoire of target antigens and T cell receptor (TCR) usage, with initial evidence of public TCR sequences that are shared by individuals with T1D. Neoepitopes derived from post-translational modifications of native antigens are emerging as novel targets that are more likely to evade self-tolerance. Further studies will determine whether T cell responses to neoepitopes are major disease drivers that could impact prediction, prevention, and therapy. This Review provides an overview of recent progress in our knowledge of autoreactive T cells that has emerged from experimental and clinical research as well as pathology investigations.

Factors That Influence the Quality of RNA From the Pancreas of Organ Donors

OBJECTIVES

Attaining high-quality RNA from the tissues or organs of deceased donors used for research can be challenging due to physiological and logistical considerations. In this investigation, METHODS: RNA Integrity Number (RIN) was determined in pancreatic samples from 236 organ donors and used to define high (≥6.5) and low (≤4.5) quality RNAs. Logistic regression was used to evaluate the potential effects of novel or established organ and donor factors on RIN.

RESULTS

Univariate analysis revealed donor cause of death (odds ratio [OR], 0.35; 95% confidence interval [CI], 0.15-0.77; P = 0.01), prolonged tissue storage before RNA extraction (OR, 0.65; 95% CI, 0.52-0.79; P < 0.01), pancreas region sampled (multiple comparisons, P < 0.01), and sample type (OR, 0.32; 95% CI, 0.15-0.67; P < 0.01) negatively influenced outcome. Conversely, duration of final hospitalization (OR, 3.95; 95% CI, 1.59-10.37; P < 0.01) and sample collection protocol (OR, 8.48; 95% CI, 3.96-19.30; P < 0.01) positively impacted outcome. Islet RNA obtained via laser capture microdissection improved RIN when compared with total pancreatic RNA from the same donor (ΔRIN = 1.3; 95% CI, 0.6-2.0; P < 0.01).

CONCLUSIONS

A multivariable model demonstrates that autopsy-free and biopsy-free human pancreata received, processed, and preserved at a single center, using optimized procedures, from organ donors dying of anoxia with normal lipase levels increase the odds of obtaining high-quality RNA.

Insulitis in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease in which autoreactive T-cells and inflammation cause severe loss of pancreatic beta cells. Insulitis, the pathologic hallmark of T1D, is an inflammatory lesion consisting of immune cell infiltrates around and within the islets. New research initiatives and methodologies are advancing our understanding of pancreas pathology. Studies have revealed the predominant cellular types that infiltrate the islets, novel molecular aspects associated with insulitis, and the coexistence of additional pathological abnormalities. While insulitis is a critical element of T1D pathology and pathogenesis, it is typically present only in a modest proportion of islets at any given time, even at diagnosis, with overall limited relation to disease duration. Thus, the relative importance of insulitis as a determining factor of diabetes symptoms at disease onset appears to have been overestimated; growing evidence also shows that beta cell loss at diagnosis is more modest than previously thought. Thus, the sole targeting of the immune system may not afford full therapeutic efficacy if dysfunction affects beta cells that are not under immune attack and this is a key contributor to symptoms. Combination therapies that promote both immunoregulation and address beta cell dysfunction should be more effective in treating this chronic disease process. It remains a major goal to clarify the relation of insulitis with the dynamics of beta cell loss and coexisting mechanisms of dysfunction, according to clinical stage; such improved understanding is key to design therapeutic strategies that target multiple pathogenic mechanisms.

Insulitis and β-Cell Mass in the Natural History of Type 1 Diabetes

Descriptions of insulitis in human islets throughout the natural history of type 1 diabetes are limited. We determined insulitis frequency (the percent of islets displaying insulitis to total islets), infiltrating leukocyte subtypes, and β-cell and α-cell mass in pancreata recovered from organ donors with type 1 diabetes (n = 80), as well as from donors without diabetes, both with islet autoantibodies (AAb(+), n = 18) and without islet autoantibodies (AAb(-), n = 61). Insulitis was observed in four of four donors (100%) with type 1 diabetes duration of ≤1 year and two AAb(+) donors (2 of 18 donors, 11%). Insulitis frequency showed a significant but limited inverse correlation with diabetes duration (r = -0.58, P = 0.01) but not with age at disease onset. Residual β-cells were observed in all type 1 diabetes donors with insulitis, while β-cell area and mass were significantly higher in type 1 diabetes donors with insulitis compared with those without insulitis. Insulitis affected 33% of insulin(+) islets compared with 2% of insulin(-) islets in donors with type 1 diabetes. A significant correlation was observed between insulitis frequency and CD45(+), CD3(+), CD4(+), CD8(+), and CD20(+) cell numbers within the insulitis (r = 0.53-0.73, P = 0.004-0.04), but not CD68(+) or CD11c(+) cells. The presence of β-cells as well as insulitis several years after diagnosis in children and young adults suggests that the chronicity of islet autoimmunity extends well into the postdiagnosis period. This information should aid considerations of therapeutic strategies seeking type 1 diabetes prevention and reversal.

Organ donor specimens: What can they tell us about type 1 diabetes?

Type 1 diabetes (T1D) is a chronic disease resulting from the destruction of pancreatic beta cells, due to a poorly understood combination of genetic, environmental, and immune factors. The JDRF Network for Pancreatic Organ donors with Diabetes (nPOD) program recovers transplantation quality pancreas from organ donors throughout the USA. In addition to recovery of donors with T1D, non-diabetic donors include those with islet autoantibodies. Donors with type 2 diabetes and other conditions are also recovered to aid investigations directed at the full spectrum of pathophysiological mechanisms affecting beta cells. One central processing laboratory conducts standardized procedures for sample processing, storage, and distribution, intended for current and future cutting edge investigations. Baseline histology characterizations are performed on the pancreatic samples, with images of the staining results provided though whole-slide digital scans. Uniquely, these high-grade biospecimens are provided without expense to investigators, working worldwide, seeking methods for disease prevention and reversal strategies. Collaborative working groups are highly encouraged, bringing together multiple investigators with different expertise to foster collaborations in several areas of critical need. This mini-review will provide some key histopathological findings emanating from the nPOD collection, including the heterogeneity of beta cell loss and islet inflammation (insulitis), beta cell mass, insulin-producing beta cells in chronic T1D, and pancreas weight reductions at disease onset. Analysis of variations in histopathology observed from these organ donors could provide for mechanistic differences related to etiological agents and serve an important function in terms of identifying the heterogeneity of T1D.

Pancreatic biopsies in type 1 diabetes: revisiting the myth of Pandora's box

Over a century ago, inquisitive physicians made remarkable discoveries regarding pancreatic pathology in individuals with diabetes, including those who were likely afflicted with the type 1 (autoimmune) form of the disease. Those studies of post-mortem tissues noted unique anatomical changes in islet architecture as well as the presence of unusual cellular infiltrates. In the time since, investigations of pancreatic pathology have, with near uniformity, been restricted to analysis of organs obtained post-mortem. While clearly beneficial for addressing questions of the disorder's pathogenesis, concern exists regarding potential artefacts that might occur through analysis of tissues that have been recovered hours, often many hours, following death. Beyond this, studies of tissues obtained long after the diagnosis of type 1 diabetes may not disclose important physiological events occurring at onset or even earlier in the natural history of disease, before symptomatic hyperglycaemia. To this end, Krogvold and colleagues (in this issue of Diabetologia, doi: 10.1007/s00125-013-3155-y) undertook a potentially high-reward strategy involving pancreatic biopsy in living adults with recent-onset type 1 diabetes. Procedures were performed under informed consent, undertaken based on recent improvements in laparoscopic techniques, and carried out by individuals with considerable surgical experience. These efforts were terminated for ethical reasons following the occurrence of serious complications (including post-operative bleeding and pancreatic leakage). The experience lends itself to analogy with the Greek myth of Pandora's box where curiosity, in terms of a desire to see what resided inside a closed container, unleashed a series of ills on humans once the container was opened. In considering the moral of that myth, one must question whether the secrets of the pancreas in those living with type 1 diabetes should, for now, remain a mystery as the process of manipulating that organ for the purpose of curiosity does not occur without harm.

Network for Pancreatic Organ Donors with Diabetes (nPOD): developing a tissue biobank for type 1 diabetes

BACKGROUND

The Network for Pancreatic Organ Donors with Diabetes (nPOD) was established to recover and characterize pancreata and related organs from cadaveric organ donors with various risk levels for type 1 diabetes (T1D). These biospecimens are available to investigators for collaborative studies aimed at addressing questions related to T1D natural history and pathogenesis.

RESEARCH DESIGN AND METHODS

Organ donors included T1D patients (new onset to long term), non-diabetic autoantibody-positive subjects, non-diabetic controls and individuals with disorders relevant to β-cell function. Pancreas recovery and transport met transplant-grade criteria. Additional samples recovered included serum, whole blood, spleen and pancreatic and non-pancreatic lymph nodes. Biospecimens were processed for cryopreserved cells, fixed paraffin and fresh frozen blocks and snap frozen samples. T1D autoantibodies, C-peptide levels and high-resolution HLA genotyping for risk alleles were also determined.

RESULTS

Over 160 donors have been enrolled (ages of 1 day to >90 years). Standard operating procedures were established along with a quality management system. Donor demographics, laboratory assays and histopathological characterizations were shared through an open online informatics system. Biospecimens were distributed to more than 60 investigators.

CONCLUSIONS

The nPOD programme provides access to high quality biospecimens without cost to investigators. Collaborations and open data sharing are emphasized to maximize research potential of each donor. On the basis of initial successes, the nPOD programme is expanding to recover additional organs relevant to T1D pathogenesis and complications from European countries (PanFin network).

Collection protocol for human pancreas

This dissection and sampling procedure was developed for the Network for Pancreatic Organ Donors with Diabetes (nPOD) program to standardize preparation of pancreas recovered from cadaveric organ donors. The pancreas is divided into 3 main regions (head, body, tail) followed by serial transverse sections throughout the medial to lateral axis. Alternating sections are used for fixed paraffin and fresh frozen blocks and remnant samples are minced for snap frozen sample preparations, either with or without RNAse inhibitors, for DNA, RNA, or protein isolation. The overall goal of the pancreas dissection procedure is to sample the entire pancreas while maintaining anatomical orientation. Endocrine cell heterogeneity in terms of islet composition, size, and numbers is reported for human islets compared to rodent islets. The majority of human islets from the pancreas head, body and tail regions are composed of insulin-containing β-cells followed by lower proportions of glucagon-containing α-cells and somatostatin-containing δ-cells. Pancreatic polypeptide-containing PP cells and ghrelin-containing epsilon cells are also present but in small numbers. In contrast, the uncinate region contains islets that are primarily composed of pancreatic polypeptide-containing PP cells. These regional islet variations arise from developmental differences. The pancreas develops from the ventral and dorsal pancreatic buds in the foregut and after rotation of the stomach and duodenum, the ventral lobe moves and fuses with the dorsal. The ventral lobe forms the posterior portion of the head including the uncinate process while the dorsal lobe gives rise to the rest of the organ. Regional pancreatic variation is also reported with the tail region having higher islet density compared to other regions and the dorsal lobe-derived components undergoing selective atrophy in type 1 diabetes. Additional organs and tissues are often recovered from the organ donors and include pancreatic lymph nodes, spleen and non-pancreatic lymph nodes. These samples are recovered with similar formats as for the pancreas with the addition of isolation of cryopreserved cells. When the proximal duodenum is included with the pancreas, duodenal mucosa may be collected for paraffin and frozen blocks and minced snap frozen preparations.