Contribution of animal models to diabetes research: Its history, significance, and translation to humans

Diabetes mellitus is still expanding globally and is epidemic in developing countries. The combat of this plague has caused enormous economic and social burdens related to a lowered quality of life in people with diabetes. Despite recent significant improvements of life expectancy in patients with diabetes, there is still a need for efforts to elucidate the complexities and mechanisms of the disease processes to overcome this difficult disorder. To this end, the use of appropriate animal models in diabetes studies is invaluable for translation to humans and for the development of effective treatment. In this review, a variety of animal models of diabetes with spontaneous onset in particular will be introduced and discussed for their implication in diabetes research.

Gut as a source of new β-cells and Segi's cap

A deficit of β-cells is a salient feature in both type 1 and type 2 diabetes mellitus. Due to the absolute lack of supplying β-cells for organ or cell transplantation, there is an urgent need to explore the efficient method to generate insulin-producing cells. Cell conversion of intestinal cryptic epithelial cells to insulin-producing β-like cells is a novel and promising therapeutic target. Activation of β-cell differentiation factors or modulation of terminally differentiated factors with forkhead homeobox O1 effectively induced such conversion, and suppressed hyperglycemia in streptozotocin-induced and non-obese diabetic (NOD) mice. Segi's cap, which was discovered >80 years ago, is composed of an aggregation of primitive granulated enteroendocrine cells, enterochromaffin cells, Paneth cells and goblet cells in the intestinal villi, and is only detected at the fetal stage. Its role has long been unknown, but the present study disclosed that it likely provides an underpin of newly generated β-like cells.

Bi-glandular and persistent enterovirus infection and distinct changes of the pancreas in slowly progressive type 1 diabetes mellitus

In slowly progressive type 1 diabetes mellitus (SPIDDM), the pancreas shows sustained islet inflammation, pancreatitis, pancreatic acinar cell metaplasia/dysplasia (ADM), and intraepithelial neoplasia (PanIN), a precancerous lesion. The mechanisms underlying these changes remain unclear. The presence of enterovirus (EV) encoded-capsid protein 1 (VP1) and -2A protease (2A^pro) and the innate immune responses of the pancreas were studied using immunohistochemistry and in situ hybridization in 12 SPIDDM and 19 non-diabetic control pancreases. VP1, 2A^pro, and EV-RNA were detected in islets and the exocrine pancreas in all SPIDDM pancreases. Innate immune receptor, melanoma differentiation-associated gene 5 (MDA5), and interferon (IFN)-beta1 were intensified in the islets of SPIDDM patients with short disease duration. However, expressions of MDA5 and IFN-beta1were suppressed in those with longer disease duration. CD3⁺ T cell infiltration was observed in the VP1- and insulin-positive islets (insulitis) and exocrine acinar cells. CD11c⁺ dendritic cells (DCs) in islets were scarce in long-term SPIDDM. This study showed the consistent presence of EV, suggesting an association with inflammatory changes in the endocrine and exocrine pancreas in SPIDDM. Suppressed expressions of MDA5 and IFN-beta1, as well as decreased numbers of DCs in the host cells, may contribute to persistent EV infection and induction of ADM/PanIN lesions, which may potentially provide a scaffold for pancreatic neoplasms.

RAGE activation in macrophages and development of experimental diabetic polyneuropathy

It is suggested that activation of receptor for advanced glycation end products (RAGE) induces proinflammatory response in diabetic nerve tissues. Macrophage infiltration is invoked in the pathogenesis of diabetic polyneuropathy (DPN), while the association between macrophage and RAGE activation and the downstream effects of macrophages remain to be fully clarified in DPN. This study explored the role of RAGE in the pathogenesis of DPN through the modified macrophages. Infiltrating proinflammatory macrophages impaired insulin sensitivity, atrophied the neurons in dorsal root ganglion, and slowed retrograde axonal transport (RAT) in the sciatic nerve of type 1 diabetic mice. RAGE-null mice showed an increase in the population of antiinflammatory macrophages, accompanied by intact insulin sensitivity, normalized ganglion cells, and RAT. BM transplantation from RAGE-null mice to diabetic mice protected the peripheral nerve deficits, suggesting that RAGE is a major determinant for the polarity of macrophages in DPN. In vitro coculture analyses revealed proinflammatory macrophage-elicited insulin resistance in the primary neuronal cells isolated from dorsal root ganglia. Applying time-lapse recording disclosed a direct impact of proinflammatory macrophage and insulin resistance on the RAT deficits in primary neuronal cultures. These results provide a potentially novel insight into the development of RAGE-related DPN.

The diversity and abundance of gut microbiota are associated with the pain sensation threshold in the Japanese population

Small fibre neuropathy (SFN) is an initial pathology of diabetic polyneuropathy (DPN). Serum lipopolysaccharide binding protein levels are positively correlated with the pain threshold in the foot, suggesting that the abundance of gut Gram-negative bacilli, which are a source of lipopolysaccharides, may be involved in the development of DPN. Furthermore, the abundance of the gut and oral microbiota is assumed to be involved in the pathogenesis of diabetes. Nevertheless, the association between SFN and the microbiota has not been clarified. A total of 1056 individuals were recruited in the 2018 Iwaki Health Promotion Project. Pain sensation was evaluated based on the pain threshold from intraepidermal electrical stimulation (PINT). Patients with PINT scores <0.15 mA were categorized into the low-PINT group (n = 718); otherwise, they were categorized into the high-PINT group (n = 283). Furthermore, each group was divided into the subjects with or without glucose tolerance based on HbA1c levels, fasting blood glucose levels and diabetic history. Principal coordinate analysis and α- and β-diversity of the microbiota were evaluated. The correlation between clinical and microbiota data was examined. Oral microbiota diversity showed no structural differences according to PINT scores, whereas principal coordinate analysis and α- and β-diversity revealed significant structural differences in gut microbiota (p < 0.01, p < 0.05 and p < 0.05, respectively), even after the participants with glucose intolerance were excluded (p < 0.01, p < 0.05 and p < 0.05, respectively). The relative abundance of the genus Bacteroides was significantly lower in high-PINT participants compared with low-PINT participants (10 ± 6.7% vs. 11.3 ± 7.0%, p < 0.01), even after the exclusion of subjects with diabetes and impaired fasting glucose (10.0 ± 6.5% vs. 11.2 ± 6.9%, p < 0.05). In univariate linear regression analyses, PINT was significantly correlated with metabolic syndrome parameters, eGFR, uric acid level and the abundance of Bacteroides. The correlation between Bacteroides and PINT scores remained significant after adjustment for multiple factors (β = -0.07181, p < 0.05). Changes of bacterial diversity and a low abundance of gut Bacteroides were correlated with elevated PINT scores in the Japanese population. This correlation may represent a new therapeutic option for SFN.

Islet microangiopathy and augmented β-cell loss in Japanese non-obese type 2 diabetes patients who died of acute myocardial infarction

AIMS/INTRODUCTION

Islets have microvessels that might develop pathological alterations similar to microangiopathy in type 2 diabetes patients. It remains unclear, however, whether the changes correlate with endocrine cell deficits or whether the presence of macroangiopathy influences the islet microvasculature in Japanese type 2 diabetes patients. In this study, we characterized changes of the islet microvessels and endocrine cells in Japanese non-obese patients with type 2 diabetes who died of acute myocardial infarction (AMI).

MATERIALS AND METHODS

Clinical profiles and islet pathology were examined for 35 diabetes patients who died of AMI (DM + AMI) and 13 diabetes patients who were free from AMI (DM). A total of 13 age-matched, individuals without diabetes who died of AMI and 16 individuals without diabetes who were free from AMI were also studied. Pancreata were subjected to morphometric evaluation of islets, including microvascular alterations of immunostained sections.

RESULTS

Body mass index in DM + AMI was comparable to those in DM. Compared with DM, DM + AMI showed greater glycated hemoglobin levels, higher prevalence of renal failure, hypertension, smaller β-cell volume density and greater amyloid area. DM + AMI showed an increased microvascular area and density compared with other groups. There was a significant increase in vascular basement membrane thickness and loss of pericytes in DM and DM + AMI compared with individuals without diabetes in each group, and the extent of thickening was correlated with the amyloid area and occurrence of β-cell loss in DM + AMI.

CONCLUSIONS

Islet microangiopathy was associated with augmented β-cell loss and amyloid deposition in non-obese Japanese type 2 diabetes patients who died of AMI.

Diabetes in Humans Activates Pancreatic Stellate Cells via RAGE in Pancreatic Ductal Adenocarcinoma

Pancreatic stellate cells (PSCs) mainly consist of cancer-associating fibroblasts in pancreatic ductal adenocarcinoma (PDAC). The receptor for advanced glycation end products (RAGE) is implicated in the pathophysiology of diabetic complications. Here, we studied the implication of RAGE in PSC activation in PDAC. The activation of cultured mouse PSCs was evaluated by qPCR. The induction of epithelial mesenchymal transition (EMT) in PDAC cell lines was assessed under stimulation with culture supernatant from activated PSCs. A total of 155 surgically resected PDAC subjects (83 nondiabetic, 18 with ≦3-years and 54 with >3-years history of diabetes) were clinicopathologically evaluated. A high-fat diet increased the expression of activated markers in cultured PSCs, which was abrogated by RAGE deletion. Culture supernatant from activated PSCs facilitated EMT of PDAC cells with elevation of TGF-β and IL-6, but not from RAGE-deleted PSCs. Diabetic subjects complicated with metabolic syndrome, divided by cluster analysis, showed higher PSC activation and RAGE expression. In such groups, PDAC cells exhibited an EMT nature. The complication of metabolic syndrome with diabetes significantly worsened disease-free survival of PDAC subjects. Thus, RAGE in PSCs can be viewed as a new promoter and a future therapeutic target of PDAC in diabetic subjects with metabolic syndrome.

Immunohistochemical detection of enteroviruses in pancreatic tissues of patients with type 1 diabetes using a polyclonal antibody against 2A protease of Coxsackievirus

INTRODUCTION

The need for antiserum for immunohistochemical detection (IHC) of enterovirus (EV) in formaldehyde fixed and paraffin-embedded (FFPE) samples is increasing. The gold standard monoclonal antibody (clone 5D8/1) against EV-envelope protein (VP1) was proven to cross-react with other proteins. Another candidate marker of EV proteins is 2A protease (2A^pro ), which is encoded by EV gene and translated by the host cells during EV replication and participates processing proproteins to viral capsid proteins.

MATERIALS AND METHODS

We raised polyclonal antiserum by immunizing a rabbit with an 18-mer peptide of Coxsackievirus B1 (CVB1)-2A^pro and examined the specificity and sensitivity for EV on FFPE tissue samples.

RESULTS

ELISA study showed a high titer of antibody for 18-mer peptide of CVB1-2A^pro , cross reacting with CVB3-2A^pro peptide. IHC demonstrated that antiserum against 2A^pro reacted with CVB1-infected and VP1-positive Vero-cells. Confocal laser scanning microscopy demonstrated that antigen stained by the 2A^pro antibody located in the same cell with VP1 stained by 5D8/1. IHC using 2A^pro antiserum showed dense staining in the islets of EV-associated fulminant type 1 diabetic pancreas and that located in the same cell stained positive for VP1 (5D8/1). Specificity of 2A^pro antiserum by IHC staining was confirmed by negative 2A^pro in 14 VP1-negative non-diabetic control pancreases.

CONCLUSION

Our study provides a new polyclonal antiserum against CVB1-2A^pro which may be useful for IHC of EV-infected human tissues stored as archive of FFPE tissue samples.

Inhibitory effects of xanthine oxidase inhibitor, topiroxostat, on development of neuropathy in db/db mice

Inflammation and oxidative stress contribute to the pathophysiology of diabetic neuropathy. According to recent evidence, the modulation of macrophage polarization in peripheral nerves represents a potential therapeutic target for diabetic neuropathy. Xanthine oxidase, which is a form of xanthin oxidoreductase, is the rate-limiting enzyme that catalyzes the degradation of hypoxanthine and xanthine into uric acid. Activation of xanthine oxidase promotes oxidative stress and macrophage activation. A preclinical study reported the beneficial effects of xanthine oxidase inhibitors on peripheral nerve dysfunction in experimental models of diabetes. However, the detailed mechanisms remain unknown. In this study, we examined the effect of the xanthine oxidase inhibitor topiroxostat on macrophage polarization and peripheral neuropathy in an obese diabetic model, db/db mice. First, the effects of xanthine oxidase inhibitors on cultured macrophages and dorsal root ganglion neurons exposed to xanthine oxidase were assessed. Furthermore, five-week-old db/db mice were administered the xanthine oxidase inhibitors topiroxostat [1 mg/kg/day (dbT1) or 2 mg/kg/day (dbT2)] or febuxostat [1 mg/kg (dbF)]. Glucose metabolism and body weight were evaluated during the experimental period. At 4 and 8 weeks of treatment, peripheral nerve functions such as nerve conduction velocities, thermal thresholds and pathology of skin and sciatic nerves were evaluated. The mRNA expression of molecules related to inflammation and oxidative stress was also measured in sciatic nerves. Untreated db/db mice and the nondiabetic db strain (db/m) were studied for comparison. An in vitro study showed that topiroxostat suppressed macrophage activation and proinflammatory but not anti-inflammatory polarization, and prevented the reduction in neurite outgrowth from neurons exposed to xanthine oxidase. Neuropathic changes exemplified by delayed nerve conduction and reduced intraepidermal nerve fiber density developed in db/db mice. These deficits were significantly prevented in the treated group, most potently in dbT2. Protective effects were associated with the suppression of macrophage infiltration, cytokine expression, and oxidative stress in the sciatic nerve and decreased plasma xanthine oxidoreductase activity. Our results revealed the beneficial effects of the xanthine oxidase inhibitor topiroxostat on neuropathy development in a mouse model of type 2 diabetes. The suppression of proinflammatory macrophage activation and oxidative stress-induced damage were suggested to be involved in this process.

Increased Oxidative Stress Underlies Abnormal Pain Threshold in a Normoglycemic Japanese Population

Normal-high HbA1c levels are a risk factor for attenuated pain sensation in normoglycemic subjects. It is unclear, however, what mechanisms underlie the pathogenesis of attenuated pain sensation in such a population. We, therefore, explored the relationship between oxidative stress (OS) and pain sensation in a rural Japanese population. A population-based study of 894 individuals (average age 53.8 ± 0.5 years) and 55 subjects with impaired fasting glucose (IFG) were enrolled in this study. Individuals with diabetes were excluded. Relationships between pain threshold induced by intraepidermal electrical stimulation (PINT) and clinico-hematological parameters associated with OS were evaluated. Univariate linear regression analyses revealed age, BMI, HbA1c, the OS biomarker urine 8-hydroxy-2'-deoxyguanosine (8-OHdG), systolic blood pressure, and decreased Achilles tendon reflex on the PINT scores. Adjustments for age, gender, and multiple clinical measures confirmed a positive correlation between PINT scores and urine 8-OHdG (β = 0.09, p < 0.01). Urine 8-OHdG correlated positively with higher HbA1c levels and age in the normoglycemic population. Unlike in the normoglycemic population, both inflammation and OS were correlated with elevated PINT scores in IFG subjects. OS may be a major contributing factor to elevated PINT scores in a healthy Japanese population.

Role of glucosamine in development of diabetic neuropathy independent of the aldose reductase pathway

Long-term metabolic aberrations contribute to the development of diabetic neuropathy but the precise mechanism or mechanisms remains elusive. We have previously shown that aldose reductase-deficient mice exhibit delayed onset and progression of neuropathy following induction of diabetes, suggesting a role both for downstream metabolites of this enzyme and also for other unrelated pathways. In this study, we have utilized comprehensive metabolomics analyses to identify potential neurotoxic metabolites in nerve of diabetic mice and explored the mechanism of peripheral nerve injury. Aldose reductase knockout and control C57Bl/6J mice were made diabetic by injection of streptozotocin and followed for 8–16 weeks. Diabetic aldose reductase knockout mice exhibited delayed onset of nerve conduction slowing compared to diabetic wild-type mice. The sciatic nerves from aldose reductase knockout mice exposed to 12 weeks of diabetes were used for metabolomics analysis and compared with analyses of nerves from age-matched diabetic wild-type mice as well as non-diabetic aldose reductase knockout and wild-type mice. Neurotoxicity of candidate metabolites was evaluated using cultured Schwann cells and dorsal root ganglion neurons, and further confirmed in vivo. Metabolomics analysis identified elevated glucosamine levels in both diabetic aldose reductase knockout and diabetic wild mice. Exposure to glucosamine reduced survival of cultured Schwann cells and neurons accompanied by increased expression of cleaved caspase 3, CCAT-enhancer-binding homologous protein and mitochondrial hexokinase-I, along with ATP depletion. These changes were suppressed by siRNA to hexokinase-I or the ATP donor, inosine, but not by the antioxidant N-acetylcysteine or the endoplasmic reticulum-stress inhibitor 4-phenylbutyrate. The O-GlcNAcylation enhancer, O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino N-phenylcarbamate, did not augment glucosamine neurotoxicity. Single dose glucosamine injection into mice caused a reduction of sciatic nerve Na, K-ATPase activity, ATP content and augmented expression of hexokinase-I, which were suppressed by pretreatment with inosine but not with 4-phenylbutyrate. Mice implanted with a subcutaneous pump to infuse glucosamine for 12 weeks developed nerve conduction slowing and intraepidermal nerve fibre loss, recapitulating prominent indices of diabetic neuropathy. While acute glucosamine neurotoxicity is unlikely to contribute substantially to the slowly developing neuropathy phenotype in humans, sustained energy deprivation induced by glucosamine may well contribute to the pathogenesis of diabetic neuropathy. Our data thus identifies a novel pathway for diabetic neuropathy that may offer a potential new therapeutic target.

Lipopolysaccharide-binding protein is a distinctive biomarker of abnormal pain threshold in the general Japanese population

INTRODUCTION

Small fiber neuropathy (SFN) is an early manifestation in diabetic polyneuropathy (DPN); however, the mechanisms are not fully understood. In diabetes, SFN is presumed to be common in individuals with overt DPN, enhancing activation of polyol pathway, oxidative stress, advanced glycation end products (AGEs), and inflammation. We explored the relationship between clinicohematological factors related to DPN and pain sensation in the Japanese population.

RESEARCH DESIGN AND METHODS

We conducted a population-based study, recruiting 1030 individuals (average age 54.4±0.5 years), in 2017, to participate in our Iwaki project. After initial screening by fasting blood glucose and glycohemoglobin A1c (HbA1c) measurements, the subjects were categorized into control (n=894), type 2 diabetes (n=81), and impaired fasting glucose (n=55) groups. Clinical data were gathered, and relationships between pain threshold from intraepidermal electrical stimulation (PINT) and DPN were examined by analysis of variance, post hoc test, and χ² tests to study correlations among and between groups of the clinical data and DPN.

RESULTS

Univariate linear regression analyses showed significant correlations between PINT and serum lipopolysaccharide-binding protein (LBP) level (ß=0.1025, p=0.001). Adjustments for the clinical measurements confirmed a positive correlation (ß=0.070, p=0.034). Logistic regression analysis revealed high LBP value (>6.7 mg/dL) as a significant risk factor toward abnormal PINT (≥0.35 mA). LBP significantly correlated with the high-sensitivity C reactive protein, inflammation marker, elevated similarly in both pre-diabetic and overt-diabetic groups, compared with controls, but it did not correlate with a decreased Achilles tendon reflex. In contrast, urine 8-hydroxy-2'-deoxyguanosine, oxidative stress marker, and pentosidine, AGEs, markedly increased in individuals with type 2 diabetes with high HbA1c.

CONCLUSIONS

Individuals with high LBP exhibited an elevated PINT in the Japanese population. Low level of inflammation evoked by metabolic endotoxemia is possibly implicated in the pathophysiology of SFN from pre-diabetic stage.

What can we learn from the islet of Joslin Medalists?

This commentary refers to the recent study of Joslin Medalists that showed evidence of residual endocrine cells still functioning in response to glucose stimuli. Islet pathology showed the ongoing remodeling influenced by autoimmune attack and glucose toxicity. The results showed the presence of functional endocrine cells that contribute to the longevity of patients with type 1 diabetes.

Beneficial effects of combination therapy of canagliflozin and teneligliptin on diabetic polyneuropathy and β-cell volume density in spontaneously type 2 diabetic Goto-Kakizaki rats

AIMS

Parasympathetic nerve (PN) signaling plays a crucial role in the maintenance of pancreatic β-cell volume density (V_β). PN may be pathologically affected in diabetic polyneuropathy (DPN). However, the association between the reduction of PNs in islets and V_β and the therapeutic effects of a DPP4 inhibitor (DPP4i) and an SGLT2 inhibitor (SGLT2i) in nonobese type 2 diabetes mellitus (T2DM) Goto-Kakizaki rats (GK) have not been investigated.

MATERIALS AND METHODS

We divided 5-week old male GK and Wistar rats (W) into a DPP4i-treated group (GKTe), SGLT2i-treated group (GKCa), and combination-treated group (GKCaTe). After 25 weeks, the pancreata was pathologically evaluated.

RESULTS

V_β in GK was significantly decreased (p < 0.01 vs. W), whereas V_β was the most well preserved in GKCaTe (p < 0.05 vs. GKTe), followed by GKTe (p < 0.05 vs. GK). The decreased amount of PNs in the islets and intraepidermal nerve fiber density (IENFD) in GK was significantly improved in the treated groups compared with GK (p < 0.05 vs. GKCa and GKTe and p < 0.01 vs. GKCaTe). PN density and IENFD were significantly correlated with V_β (r = 0.55, p < 0.01 and r = 0.54, p < 0.01, respectively). IENFD was identified as a surrogate marker for the prediction of V_β (cutoff value, 16.39).

CONCLUSIONS

The combination therapy of DPP4i and SGLT2i improved V_β accompanied by PNs density and IENFD. IENFD was proportionally correlated with V_β. Therefore, the prevention of DPN development may be concurrently beneficial for the preservation of V_β in nonobese T2DM.

Diabetes, an independent poor prognostic factor of non-B non-C hepatocellular carcinoma, correlates with dihydropyrimidinase-like 3 promoter methylation

A concurrent increase in the prevalence of hepatocellular carcinoma (HCC) with that of type 2 diabetes (T2D) and obesity has been reported in the absence of hepatitis B virus surface antigen-negative/hepatitis C virus antibody-negative HCC (NBNC-HCC). However, the prognostic relevance of this association remains unclear. Promoter methylation (PM) of the dihydropyrimidinase-like 3 gene (DPYSL3) has been implicated in virus-related HCC. However, it remains unclear whether T2D influences PM in NBNC-HCC. We determined the influence of T2D on clinicopathological profile and PM of DPYSL3 and CDK2NA in patients with NBNC-HCC who were divided into two groups: non-diabetes (non-DM; n = 46) and diabetes (DM; n = 47). DM was associated with a higher Union for International Cancer Control grade, marginal vascular invasion and tumour cell proliferation irrespective of the duration of T2D as well as higher rates of PM of DPYSL3 than non-DM; however, PM of CDK2NA was similar between both groups. PM of DPYSL3 reduced its expression which inversely correlated with reduced patient survival. In conclusion, T2D is associated with poor prognosis of NBNC-HCC in which a high frequency of PM of DPYSL3 may play a pivotal role in its pathogenesis.

Corrigendum: Normal High HbA1c a Risk Factor for Abnormal Pain Threshold in the Japanese Population

[This corrects the article DOI: 10.3389/fendo.2019.00651.].

Unique Inflammatory Changes in Exocrine and Endocrine Pancreas in Enterovirus-Induced Fulminant Type 1 Diabetes

CONTEXT

There are scant reports on the pathological changes of the exocrine and endocrine pancreas in fulminant type 1 diabetes mellitus (FT1DM).

OBJECTIVE

To clarify the distinct pathological changes in the exocrine as well as the endocrine pancreas shortly after onset of diabetes in FT1DM.

DESIGN

The exocrine and endocrine pancreases of 3 patients with FT1DM and 17 nondiabetic controls were immunohistochemically examined for islet and exocrine tissue inflammation, infiltrating mononuclear cell (MNC) CD subtype, enterovirus capsid protein 1 (VP1) localization, and CXC chemokine ligand 10 (CXCL10) and CXC chemokine receptor 3 (CXCR3) expressions.

RESULTS

The median frequency of insulitis in the 3 FT1DM pancreases was 60%. In the nondiabetic control pancreases, no insulitis was observed. In the islets of FT1DM, the numbers of CD45+, CD3+, CD8+, CD68+, and CD11c+ MNCs were significantly higher than those of the control group. In the exocrine pancreas of FT1DM, the numbers of CD3+ T cells, CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were significantly higher than those of the control group. Infiltrating CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were observed around exocrine acinar cells in FT1DM. There was a close association between VP1 and CXCL10 expression in pancreatic exocrine ductal cells and acinar cells as well as islet cells in FT1DM. CXCL10+ exocrine cells were surrounded by CXCR3+ T cells.

CONCLUSION

The pathological findings suggested that suppression of the activated CXCL10-CXCR3 axis in the exocrine as well as the endocrine pancreas is a novel therapeutic target in FT1DM and possibly in enterovirus-associated acute-onset type 1 diabetes.

Cutaneous microangiopathy in patients with type 2 diabetes: Impaired vascular endothelial growth factor expression and its correlation with neuropathy, retinopathy and nephropathy

AIMS/INTRODUCTION

To examine the three-dimensional morphology and vascular endothelial growth factor (VEGF) expression of skin microvasculature in patients with type 2 diabetes in relation to neuropathy, retinopathy and nephropathy.

MATERIALS AND METHODS

The present study enrolled 17 individuals with type 2 diabetes and 16 without. Skin sections were double-immunostained for type IV collagen and VEGF-A or protein gene product 9.5. Projected images from confocal microscopy served to quantify the occupancy rate of subepidermal type IV collagen-immunoreactive microvascular basement membrane area (OR-T4MBM), subepidermal VEGF-A-immunoreactive area and the VEGF/T4MBM ratio, as well as the protein gene product 9.5-immunoreactive intraepidermal nerve fiber density. Reduced intraepidermal nerve fiber density was applied for the diagnosis of neuropathy, fundic ophthalmoscopy and fluorescein angiography for retinopathy, and microalbuminuria or persistent proteinuria for nephropathy.

RESULTS

A total of 12 patients with diabetes had neuropathy, 10 had retinopathy and eight had nephropathy. Regardless of the presence or absence of neuropathy, retinopathy or nephropathy, OR-T4MBM was significantly increased in patients with diabetes compared with individuals without diabetes. In contrast, VEGF/T4MBM ratio was significantly decreased in those with neuropathy and retinopathy, as well as in those with and without nephropathy, whereas a trend toward a decreased VEGF/T4MBM ratio was seen in patients without retinopathy, as compared with individuals without diabetes.

CONCLUSIONS

The present study is the first report to show that cutaneous microangiopathy, as indicated by subepidermal microvascular proliferation and impaired VEGF expression, appears to occur before the development of overt clinical neuropathy, retinopathy or nephropathy in patients with type 2 diabetes.

Normal High HbA1c a Risk Factor for Abnormal Pain Threshold in the Japanese Population

Purpose: Small fiber dysfunction is common in subjects with diabetic polyneuropathy (DPN). It is unsettled, however, whether marginal glucose intolerance is implicated in the onset and progression of small fiber dysfunction. Herein, we explored the relationship between glycated hemoglobin levels (HbA1c) and pain sensation in the Japanese population. Methods: A population-based study of 894 individuals (352 men, 542 women; average age 53.8 ± 0.5 years) and 55 subjects with impaired fasting glucose (IFG) in the 2017 Iwaki project were enrolled in this study. Individuals with diabetes were excluded. Relationships between pain threshold for intraepidermal electrical stimulation (P-IES) and parameters associated with metabolic syndrome were examined. Results: P-IES was elevated with increasing of age in women but not in men. Average P-IES (mA) was increased in IFG subjects (n = 55, 0.20 ± 0.03) compared with normoglycemic/non-IFG individuals (n = 894, 0.15 ± 0.11) (p < 0.01). It was comparable between IFG and a group of normal high HbA1c (5.9-6.4%). Univariate linear regression analyses showed no influence of sex, triglyceride, or cholesterol on the value of P-IES. In contrast, there were significant correlations between P-IES and serum HbA1c level (ß = 0.120, p < 0.001) Adjustments for the multiple clinical measurements confirmed positive correlation of P-IES with HbA1c (ß = 0.077, p = 0.046). Conclusion: Individuals with normal high HbA1c exhibited an elevated P-IES in a healthy Japanese population which may be useful for the screening of subclinical DPN.

Crucial role of Reg I from acinar-like cell cluster touching with islets (ATLANTIS) on mitogenesis of beta cells in EMC virus-induced diabetic mice

Recently, we reported the presence of distinct cell clusters named acinar-like cell clusters touching Langerhans islets with thin interstitial surrounding (ATLANTIS) in human pancreas. A morphological study in humans demonstrated that ATLANTIS and islet cell clusters are found together in the microenvironment enclosed by a common basement membrane, and ATLANTIS releases vesicles containing Regenerating gene protein (REG Iα) to islet cell clusters. We examined 1) the presence or absence of ATLANTIS in homozygous Reg I (mouse homologue of human REG Iα) deficient (Reg I^-/-) and wild-type mice, and 2) the possible role of ATLANTIS in the regeneration of beta cell clusters after encephalomyocarditis (EMC) virus (D-variant) infection in Reg I^-/- and wild-type mice. ATLANTIS was found in both wild-type and Reg I^-/- mice. In both groups, mean blood glucose increased transiently to greater than 14.0 mmol/L at 5 days after EMC virus infection and recovered to baseline at 12 days. At 12 days after EMC virus infection, lower BrdU labeling indices were observed in islet beta cells of Reg I^-/- mice compared to wild-type mice. Beta cell volume 12 days after EMC virus infection in Reg I^-/- mice did not differ from that of wild-type mice. These results suggest that Reg I, which is released from ATLANTIS to islet beta cell clusters, has a crucial role in beta cell regeneration in EMC virus-induced diabetes. The presence of mechanism(s) other than that mediated by Reg I in beta cell restoration after destruction by EMC virus was also suggested.

Worsened outcome in patients with pancreatic ductal carcinoma on long-term diabetes: association with E-cadherin1 (CDH1) promoter methylation

Prevalence of pancreatic ductal carcinoma (PDC) is nearly twice in patients with diabetes mellitus, but the reason for this close association remains obscure. Recently promoter methylation of E-cadherin1 (CDH1) and CDKN2A genes, encoding E-cadherin and P16 respectively, are invoked in development of PDC. It is still unclear whether diabetes affects such epigenetic changes and malignant behavior in PDC. In this study, we studied whether diabetes influences the clinico-pathological profile and methylation status of CDH1 and CDKN2A genes in patients with PDC. PDC subjects were divided into 3 groups; 59 cases without diabetes (non-DM), 17 cases with short-term diabetes (short-DM)(diabetes duration 3 yrs>) and 33 cases with long-term diabetes (long-DM)(≧3 yrs). Compared to non-DM or short-DM, long-DM was associated with a higher histological grade of malignancy and a higher tumor stage. Promoter methylation of both CDH1 and CDKN2A was encountered more frequently in PDC patients with long-DM than non-DM or short DM. Cases with CDH1 promoter methylation showed reduced E-cadherin expression and worsened survival. We consider that the presence of long-DM has a negative impact on the prognosis of PDC patients which may be relevant to a high frequency of promoter methylation of CDH1.

Pancreas Atrophy and Islet Amyloid Deposition in Patients With Elderly-Onset Type 2 Diabetes

CONTEXT

With prolonged life expectancy, we often encounter patients with elderly-onset type 2 diabetes mellitus (eT2DM). Although the clinical features of eT2DM are suggested to be different from those in patients with middle-age-onset type 2 diabetes mellitus (mT2DM), the islet pathologic features in eT2DM have not been addressed.

OBJECTIVE

We attempted to characterize the pancreatic pathology in eT2DM and sought its clinical implications.

MATERIALS AND METHODS

Pancreata from 13 young nondiabetic (age, 20 to 29 years), 27 patients with mT2DM (age, 45 to 87 years), 22 middle-age subjects without T2DM, 15 subjects with eT2DM (age, 85 to 100 years), and 30 elderly subjects without T2DM were investigated. Together with conventional microscopic observations, morphometric analysis on the islet, islet endocrine cells, and amyloid deposition was conducted on immunostained sections.

RESULTS

The estimated age of diabetes onset was 80.8 ± 1.4 years (mean ± standard error) in the eT2DM group and that of the mT2DM group was 48.3 ± 2.4 years. The pancreatic weight was nearly 50% less in the eT2DM group than in the other groups, showing duct obstruction with epithelial hyperplasia, marked acinar atrophy, fibrosis, and amyloid deposition in the islet. The islet mass was significantly reduced in the eT2DM group. The amyloid volume density correlated inversely with the β-cell volume density but not with the body mass index in the eT2DM group. Laboratory data showed mild elevation of serum amylase in the eT2DM group, although clinical signs and symptoms of pancreatitis were not apparent.

CONCLUSIONS

eT2DM is distinct from mT2DM and characterized by pancreas atrophy, ductal lesions, and amyloid deposition.

Impaired Axonal Regeneration in Diabetes. Perspective on the Underlying Mechanism from In Vivo and In Vitro Experimental Studies

Axonal regeneration after peripheral nerve injury is impaired in diabetes, but its precise mechanisms have not been elucidated. In this paper, we summarize the progress of research on altered axonal regeneration in animal models of diabetes and cultured nerve tissues exposed to hyperglycemia. Impaired nerve regeneration in animal diabetes can be attributed to dysfunction of neurons and Schwann cells, unfavorable stromal environment supportive of regenerating axons, and alterations of target tissues receptive to reinnervation. In particular, there are a number of factors such as enhanced activity of the negative regulators of axonal regeneration (e.g., phosphatase and tensin homolog deleted on chromosome 10 and Rho/Rho kinase), delayed Wallerian degeneration, alterations of the extracellular matrix components, enhanced binding of advanced glycation endproducts (AGEs) with the receptor for AGE, and delayed muscle reinnervation that can be obstacles to functional recovery after an axonal injury. It is also noteworthy that we and others have observed excessive neurite outgrowth from peripheral sensory ganglion explants from streptozotocin (STZ)-diabetic mice in culture and enhanced regeneration of small nerve fibers after sciatic nerve injury in STZ-induced diabetic rats. The excess of abortive neurite outgrowth may lead to misconnections of axons and target organs, which may interfere with appropriate target reinnervation and functional repair. Amelioration of perturbed nerve regeneration may be crucial for the future management of diabetic neuropathy.

Diabetes and pancreas size, does it matter?

Imaging studies of the pancreas provide valuable information on the pathophysiology of diabetes and direction of the clinical management. Comparative studies on the imaging and microscopic pathology will be required to validate the importance of the images.

Four-year sequential nerve conduction changes since first visit in Japanese patients with early type 2 diabetes

Aims/Introduction

Despite being the most common complication of diabetes, the pattern of clinical development of diabetic neuropathy is not well‐known. In the present study, we retrospectively examined sequential changes in nerve conduction studies (NCS) for 4 years to characterize the way neuropathic changes develop in patients with type 2 diabetes.

Materials and Methods

We randomly selected 158 patients with type 2 diabetes who newly visited Naka Memorial Clinic, Ibaraki, Japan, and underwent serial 4‐year NCS. Records of clinical profile, signs and symptoms of neuropathy, and NCS data from median and tibial nerves were extracted to determine the progression of neuropathy. NCS data were represented by motor nerve conduction velocities, amplitudes of compound muscle action potentials (CMAPs) and minimal latencies of F‐wave.

Results

The prevalence of clinical neuropathy in 158 cases was 30% at baseline and 29% at the end of the study, with improvement of glycated hemoglobin (8.6–6.9%). Over 4 years, there were no changes of the signs and symptoms of neuropathy. Motor nerve conduction velocities were slightly improved or consistent at the fourth year compared with those at the beginning (+1.5% in median nerve, P < 0.05; +0.8%, not significant in the tibial nerve). The extent of the glycated hemoglobin correction correlated with the improvement of motor nerve conduction velocity. In contrast, CMAPs of both median and tibial nerves were decreased (−11.6%, P < 0.01; −3.7%, P < 0.05, respectively). For the decrease in CMAPs, no specific risk factors were identified by logistic regression analysis.

Conclusions

The present study showed progressive decline of CMAPs despite improved glycemic controls or the lack of NCV slowing in patients with early type 2 diabetes.

mRNA expression of delta-HER2 and its clinicopathological correlation in HER2-overexpressing breast cancer

Delta-human epidermal growth factor receptor 2 (HER2) is a splice variant of HER2, which lacks 16 amino acids in the extracellular domain. The aim of the present study was to elucidate the expression of delta-HER2 and its clinicopathological correlation in Japanese patients with HER2-overexpressing breast cancer. A total of 40 cases of HER2-overexpressing breast cancer were investigated. The mRNA expression levels of wild type (wt)-HER2 and delta-HER2 were quantitated by quantitative polymerase chain reaction using RNA extracted from formalin-fixed paraffin-embedded specimens. In addition, the activated form of phosphorylated-SRC (pSRC) and Ki-67 were detected by immunostaining. The mRNA expression levels of wt-HER2 varied largely, and the mRNA levels of delta-HER2 were correlated with those of wt-HER2. Furthermore, the enhanced immunostaining of pSRC was detected in 15 cases. Unsupervised hierarchal clustering of wt-HER2, delta-HER2 and pSRC was used to separate the cases into three clusters. In the first cluster, the levels of wt-HER2 and delta-HER2 were low, and pSRC immunostaining was low. Two other clusters were characterized by moderately and highly increased levels of wt-HER2 and delta-HER2 mRNA expression and enhanced pSRC. The delta/wt ratio was higher in the first cluster. Positive lymph node status and recurrence were more frequent in the first cluster compared with those in the two other clusters. Furthermore, the delta/wt ratio was significantly increased in lymph node-positive and recurrent cases, compared with in lymph node-negative and non-recurrent cases. The present study demonstrated that delta-HER2 was expressed in Japanese patients with HER2-overexpressing breast cancer. High mRNA expression levels of delta-HER2 were associated with pSRC and increased proliferation of tumor cells. A poor prognosis may be predicted by the increase in delta/wt ratio in HER2-overexpressing breast cancer.

Is Stem Cell Transplantation Ready for Prime Time in Diabetic Polyneuropathy?

Diabetic polyneuropathy (DPN) is the most common complication that emerges early in patients who have diabetes. Curative treatment for overt or symptomatic DPN has not been established, requiring much effort to explore new modalities. Thus, the use of various kinds of stem cells as a potential therapeutic option for DPN is of particular interest. The beneficial effects were proposed to be attributed to either cytokine released from transplanted stem cells or the differentiation of stem cells to substitute the damaged peripheral nerve. Furthermore, based on the concept that humoral factors secreted from stem cells play a pivotal role in tissue regeneration, the utilization of conditioned medium derived from the stem cell culture serves as a novel tool for regenerative therapy. However, many questions have not been yet answered to determine whether stem cell therapy is essential in clinical application of DPN. In this report, we review the current status of preclinical studies on stem cell therapy for DPN and discuss future prospects.

Embolisation of Ruptured Cerebral Aneurysms with Interlocking Detachable Coils in Acute Stage

Twelve cases of ruptured cerebral aneurysm were treated in acute stage with interlocking detachable coils (IDC, Target Therapeutics, Fremont, California) and the outcome was assessed.

IDCs were placed intra-aneurysm for intra-aneurysmal occlusion, or intra-artery for proximal occlusion. Cases: age 36–84 (mean; 60) y.o., 11 females and 1male; 1, 5, 4 and 2 patients were categorised (Hunt and Hess) as grades 1, 2, 3 and 4 respectively. An intra-aneurysmal occlusion in ten cases and a proximal occlusion in two were performed on day 1–11 (mean 4).

On angiograms and CT findings, the ruptured point seemed to have occluded in all cases. The occlusion rate was 100% in five cases, 95% in two, 90% in three, 80% in one, and less than 50% in one.

There were two cases of technical complication, one a coil migration and the other an aneurysmal perforation with IDC.

Their Glasgow Outcome Scale six months after embolisation was graded as good recovery in four cases, moderately disabled state in two, severely disabled state in one, and dead in five. Follow-up angiograms taken four to six months after embolisation showed an intra-aneurysmal coil compaction in five cases. Two of these were treated by a second embolisation or by neck clipping followed by aneurysmal resection, but another two were observed without any treatment and the last one died of rebleeding. Histological examination of the resected embolised aneurysm revealed slight organization around coils but no endothelialisation over the aneurysmal orifice.

In our experience, coil embolisation with IDC for acute ruptured aneurysm is a promising means of preventing rerupture during subacute stage.

Neuropathy in the spontaneously hypertensive rat: An electrophysiological and histological study

INTRODUCTION

Hypertension is identified as a risk factor for development of polyneuropathy. In this study we examined nerve conduction and morphological alteration of peripheral nerves in spontaneously hypertensive rats (SHR).

METHODS

Motor nerve conduction velocity (MNCV) in the sciatic-tibial nerve and sensory nerve conduction velocity (SNCV) in the sural nerve were measured. Pathological investigations included spinal cord, dorsal root ganglion, and hindlimb nerves in SHR and Wistar-Kyoto rats (WKY) aged 4-64 weeks.

RESULTS

Blood pressure was significantly higher in SHR than WKY animals at 4 weeks and elevated further with aging. MNCV and SNCV were significantly slower in SHR compared with WKY after age 24 weeks. Prominent morphological changes in SHR nerves included axonal atrophy and myelin splitting. SHR also had endoneurial microangiopathy with reduplication of basement membrane.

CONCLUSIONS

SHR showed slowed nerve conduction velocity and pathological abnormalities of hindlimb nerves. Sustained severe hypertension may cause axonal atrophy and endoneurial microangiopathy. Muscle Nerve 54: 756-762, 2016.

Glucotoxic Mechanisms and Related Therapeutic Approaches

Neuropathy is the earliest and commonest complication of diabetes. With increasing duration of diabetes, frequency and severity of neuropathy are worsened. Long-term hyperglycemia is therefore implicated in the development of this disorder. Nerve tissues require glucose energy to function and survive. Upon excessive glucose entry into the peripheral nerve, the glycolytic pathway and collateral glucose-utilizing pathways are overactivated and initiate adverse effects on nerve tissues. During hyperglycemia, flux through the polyol pathway, formation of advanced glycation end-products, production of free radicals, flux into the glucosamine pathway, and protein kinase C activity are all enhanced to negatively influence nerve function and structure. Suppression of these aberrant metabolic pathways has succeeded in prevention and inhibition of the development of neuropathy in animal models with diabetes. Satisfactory results were not attained, however, in patients with diabetes and further clinical trials are required. In this review, the author summarizes the hitherto proposed theories on the pathogenesis of diabetic neuropathy related to glucose metabolism and future prospects for the effective treatment of neuropathy.

Dynamic pathology of islet endocrine cells in type 2 diabetes: β-Cell growth, death, regeneration and their clinical implications

Diabetes is defined as a disease of hyperglycemic metabolic disorder caused by impaired insulin action or low insulin secretion, resulting in the occurrence of vascular complications. Based on this definition, diabetes therapy has long been oriented to correct hyperglycemia against the specific complications of diabetes. This definition has posed some difficulties, however, in understanding of the pathophysiology of this complicated disease and as such in the establishment of an effective treatment. With continuing efforts to explore the structural basis for diabetes onset and methodological development of immunohistochemistry, progressive decline of β-cells is now established as a salient feature of type 2 diabetes. Accordingly, diabetes therapy has now turned out to protect β-cells concurrently with the correction of hyperglycemia. Together with this effort, exploration of the means to regenerate β-cells or to supply new β-cells by, for example, induced pluripotential stem cells, are vigorously made with the search for the mechanism of β-cell decline in diabetes. In the present review, we describe the advances in the islet pathology in type 2 diabetes with special reference to the dynamic alterations of islet endocrine cells in the milieu of maturation, obesity, aging and ethnic differences. The effect of amyloid deposition is also discussed. We hope it will help with understanding the pathophysiology of diabetes, and suggest the future direction of diabetes treatment.

The dipeptidyl peptidase IV inhibitor vildagliptin suppresses development of neuropathy in diabetic rodents: effects on peripheral sensory nerve function, structure and molecular changes

Incretin-related therapy was found to be beneficial for experimental diabetic neuropathy, but its mechanism is obscure. The purpose of this study is to explore the mechanism through which dipeptidyl peptidase IV inhibitor, vildagliptin (VG), influences neuropathy in diabetic rodents. To this end, non-obese type 2 diabetic Goto-Kakizaki rats (GK) and streptozotocin (STZ)-induced diabetic mice were treated with VG orally. Neuropathy was evaluated by nerve conduction velocity (NCV) in both GK and STZ-diabetic mice, whereas calcitonin-gene-related peptide expressions, neuronal cell size of dorsal root ganglion (DRG) and intraepidermal nerve fiber density were examined in GK. DRG from GK and STZ-diabetic mice served for the analyses of GLP-1 and insulin signaling. As results, VG treatment improved glucose intolerance and increased serum insulin and GLP-1 in GK accompanied by the amelioration of delayed NCV and neuronal atrophy, reduced calcitonin-gene-related peptide expressions and intraepidermal nerve fiber density. Diet restriction alone did not significantly influence these measures. Impaired GLP-1 signals such as cAMP response element binding protein, protein kinase B/Akt (PKB/Akt) and S6RP in DRG of GK were restored in VG-treated group, but the effect was equivocal in diet-treated GK. Concurrently, decreased phosphorylation of insulin receptor substrate 2 in GK was corrected by VG treatment. Consistent with the effect on GK, VG treatment improved NCV in diabetic mice without influence on hyperglycemia. DRG of VG-treated diabetic mice were characterized by correction of GLP-1 signals and insulin receptor substrate 2 phosphorylation without effects on insulin receptor β expression. The results suggest close association of neuropathy development with impaired signaling of insulin and GLP-1 in diabetic rodents. Diabetic neurons are resistant to insulin and such insulin resistance may contribute to development of neuropathy. DPP-IV inhibitor, vildagliptin, corrected insulin resistance and improved neuropathy irrespective of blood glucose via augmented action of GLP-1.

Phenotyping animal models of diabetic neuropathy: a consensus statement of the diabetic neuropathy study group of the EASD (Neurodiab)

NIDDK, JDRF, and the Diabetic Neuropathy Study Group of EASD sponsored a meeting to explore the current status of animal models of diabetic peripheral neuropathy. The goal of the workshop was to develop a set of consensus criteria for the phenotyping of rodent models of diabetic neuropathy. The discussion was divided into five areas: (1) status of commonly used rodent models of diabetes, (2) nerve structure, (3) electrophysiological assessments of nerve function, (4) behavioral assessments of nerve function, and (5) the role of biomarkers in disease phenotyping. Participants discussed the current understanding of each area, gold standards (if applicable) for assessments of function, improvements of existing techniques, and utility of known and exploratory biomarkers. The research opportunities in each area were outlined, providing a possible roadmap for future studies. The meeting concluded with a discussion on the merits and limitations of a unified approach to phenotyping rodent models of diabetic neuropathy and a consensus formed on the definition of the minimum criteria required for establishing the presence of the disease. A neuropathy phenotype in rodents was defined as the presence of statistically different values between diabetic and control animals in 2 of 3 assessments (nocifensive behavior, nerve conduction velocities, or nerve structure). The participants propose that this framework would allow different research groups to compare and share data, with an emphasis on data targeted toward the therapeutic efficacy of drug interventions.

Advances in pathology of diabetes from pancreatic islets to neuropathy--a tribute to Paul Langerhans

There emerges a world epidemic of diabetes, afflicting over 3.8 billion people globally. The socio-economic burden of this disorder is tremendous and there is an urgent need to solve the problems incurred from this disorder and to establish an efficient way of prevention and treatment. Fundamental pathology of diabetes has been too diverse to reach a simple etiology and the mechanisms of how the lesions specific to diabetes develop are yet to be clear. Nevertheless, there has been slow but significant advancement in the understanding of the disease based on characterization of the salient features of pathological lesions in human diabetic subjects. Progressive decline of islet β cells associated with increased α cell volume density was found to account for clinical manifestation of hypoinsulinemia and hyperglucagonemia in type 2 diabetes. Concurrently, signs of complications represented by distal nerve fiber loss in the skin commences from the beginning of this disease. Thus the pathological studies disclosed the major attributes in this disorder targeting the islet of pancreas and epidermal nerve, both of which were discovered by Paul Langerhans more than 140 years ago. In this review, I attempt to summarize the progress in pathology of diabetes which Langerhans opened this field.

Tumor microenvironment and RIG-I signaling molecules in Epstein Barr virus-positive and -negative classical Hodgkin lymphoma of the elderly

Classical Hodgkin lymphoma (CHL) is a B-cell neoplasm characterized by Hodgkin and Reed-Sternberg (HRS) cells. Its prevalence exhibits a bimodal pattern of peaking in young adults and the elderly. There is an association with Epstein-Barr virus (EBV) infection in about 50% of cases of CHL of the elderly, and the outcome of these patients is unfavorable. It is not well known how the latent infection of EBV is involved in the pathophysiology of CHL of the elderly. To address this issue, we examined the tumor microenvironment (TME) and the expression of molecules related to EBV infection in HRS cells in 10 EBV-positive CHL and 7 EBV-negative CHL patients older than 50 years. In EBV-positive CHL, we found an increased population of FOXP3(+) cells, while that of granzyme B(+) cells was reduced, compared with those in EBV-negative CHL. The expression of inhibitory chemokine CCL20 was increased in EBV-positive HRS cells compared with that in EBV-negative HRS cells. In addition, despite increased expression of a pattern recognition receptor, RIG-I, in intracellular innate immunity, there was no evidence of interferon regulatory factor 3 activation or interferon-ß induction in EBV-positive HRS cells in CHL of the elderly. The disease recurred frequently (50%) in EBV-positive CHL. The current study thus suggests the possibility that the latent infection of EBV alters the expression of chemokines and the innate immunity response in HRS cells and modulates TME to an immunosuppressive state, which may account for the unfavorable disease course in CHL of the elderly.

Neurological Symptoms of Sarcoidosis-induced Small Fiber Neuropathy Effectively Relieved with High-dose Steroid Pulse Therapy

A 59-year-old woman was admitted to our hospital for an evaluation of a 10-day history of progressive pain and hypoesthesia of the right lower back associated with fever and constipation. Sarcoidosis was confirmed on mediastinal lymph node and skin biopsies. Although the neurological symptoms were suspected due to sarcoidosis-induced nerve dysfunction, nerve conduction studies and other routine examinations did not show any abnormalities. The intraepidermal nerve fiber density assessed on a skin biopsy was significantly reduced, suggesting small-fiber neuropathy (SFN). The patient was finally diagnosed with sarcoidosis-induced SFN, and her neurological symptoms were effectively relieved with high-dose steroid therapy.

The expression of glucagon-like peptide-1 receptor and dipeptidyl peptidase-IV in neuroendocrine neoplasms of the pancreas and gastrointestinal tract

Neuroendocrine neoplasm (NEN) of the pancreas and gastrointestinal tract is infrequent but often produces hormones to cause distinct clinical features. Glucagon-like peptide-1 receptor (GLP1R) is a G-protein coupled receptor for GLP1, which is cleaved by dipeptidyl peptidase (DPP)-IV, a peptidase that regulates the activity of peptide hormones. Since these molecules are involved in the neuroendocrine function of NEN, they could serve molecular targets for diagnosis and therapy of NEN. However, the expressions of these molecules in NEN are not well studied. We therefore examined the expression of GLP1R and DPP-IV in 22 cases of pancreatic NEN (P-NEN) and 20 cases of gastrointestinal NEN (GI-NEN) by immunostaining. GLP1R was expressed in all eight insulinomas (100 %) but so in only four out of 14 cases (29 %) of non-insulinomas. In contrast to GLP1R, DPP-IV was detected in one out of eight insulinomas (13 %) and in 12 out of 14 cases (86 %) of non-insulinomas. In GI-NEN, GLP1R was negative in all 10 cases of the foregut NEN, whereas it was expressed in all three cases (100 %) of midgut NEN and four out of seven cases (57 %) of hindgut NEN. DPP-IV was expressed in five out of 10 cases (50 %) of the foregut NEN. The expression was detected in two out of three cases (67 %) of midgut NEN and in all seven cases (100 %) of hindgut NEN. In conclusion, we found distinct expression patterns of GLP1R and DPP-IV depending on the neuroendocrine cell types in P-NEN and the anatomical sites in GI-NEN.

Islet amyloid with macrophage migration correlates with augmented β-cell deficits in type 2 diabetic patients

AIMS

Islet amyloid is a hallmark in type 2 diabetic subjects, but its implication in clinical features and development of islet pathology is still unclear.

METHODS

From 118 autopsy cases with type 2 diabetes, 26 cases with islet amyloid deposition (DA+) were selected. Twenty diabetic subjects without obvious amyloid deposition (DA-) matched for the age and diabetes duration and 20 non-diabetic subjects (ND) served for comparison. We examined the severity of amyloid deposition and its relationships with population of endocrine cells, expression of cell damage markers or macrophage infiltration. Correlation of clinical profile with islet pathology was also sought on the subset of the investigated patients.

RESULTS

β-Cell volume density was nearly 40% less in DA+ and 20% less in DA- when compared to ND. Severity of amyloid deposition correlated with reduced volume densities of β-cell and α-cell, and increased body mass index (BMI), but not with duration of diabetes, age or HbA1c. Amyloid-rich islets contained an increased number of macrophages mixed with β-cells with oxidative stress-related DNA damage, characterized by γH2AX expression, and suppressed (pro)insulin mRNA expression.

CONCLUSIONS

In Japanese type 2 diabetic patients, islet amyloid was more common with severe β-cell loss and high BMI, associated with macrophage infiltration.

Involvement of oxidative stress-induced DNA damage, endoplasmic reticulum stress, and autophagy deficits in the decline of β-cell mass in Japanese type 2 diabetic patients

OBJECTIVE

Deficits of β-cells characterize the islet pathology in type 2 diabetes. It is yet to be clear how the β-cell loss develops in type 2 diabetes. We explored the implication of oxidative stress, endoplasmic reticulum (ER)-induced stress, and autophagy deficit in the β-cell decline in Japanese type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

Pancreases from recent autopsy cases of 47 type 2 diabetic and 30 nondiabetic subjects were investigated on the islet structure with morphometric analysis. Volume densities of islet (Vi), β-cell (Vβ), and α-cell (Vα) were measured. To evaluate cell damage of endocrine cells, immunohistochemical expressions of oxidative stress-related DNA damage as expressed by γH2AX, ER stress-related cell damage as CCAAT/enhancer 1 binding protein-β (C/EBP-β), and autophagy deficit as P62 were semiquantified, and their correlations to islet changes were sought.

RESULTS

Compared with nondiabetic subjects, Vβ was reduced in diabetic subjects. Contrariwise, there was an increase in Vα. There was a significant link between reduced Vβ and increased HbA1c levels (P < 0.01) and a trend of inverse correlation between Vβ and duration of diabetes (P = 0.06). Expressions of γH2AX, P62, and C/EBP-β were all enhanced in diabetic islets, and reduced Vβ correlated with the intensity of γH2AX expression but not with C/EBP-β or P62 expressions. Combined expressions of γH2AX, P62, and C/EBP-β were associated with severe reduction of Vβ.

CONCLUSIONS

β-Cell deficit in type 2 diabetes was associated with increased oxidative stress and may further be augmented by autophagic deficits and ER stress.

Mechanism of diabetic neuropathy: Where are we now and where to go?

Neuropathy is the most common complication of diabetes. As a consequence of longstanding hyperglycemia, a downstream metabolic cascade leads to peripheral nerve injury through an increased flux of the polyol pathway, enhanced advanced glycation end‐products formation, excessive release of cytokines, activation of protein kinase C and exaggerated oxidative stress, as well as other confounding factors. Although these metabolic aberrations are deemed as the main stream for the pathogenesis of diabetic microvascular complications, organ‐specific histological and biochemical characteristics constitute distinct mechanistic processes of neuropathy different from retinopathy or nephropathy. Extremely long axons originating in the small neuronal body are vulnerable on the most distal side as a result of malnutritional axonal support or environmental insults. Sparse vascular supply with impaired autoregulation is likely to cause hypoxic damage in the nerve. Such dual influences exerted by long‐term hyperglycemia are critical for peripheral nerve damage, resulting in distal‐predominant nerve fiber degeneration. More recently, cellular factors derived from the bone marrow also appear to have a strong impact on the development of peripheral nerve pathology. As evident from such complicated processes, inhibition of single metabolic factors might not be sufficient for the treatment of neuropathy, but a combination of several inhibitors might be a promising approach to overcome this serious disorder. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00070.x, 2010)

Polyol pathway and diabetic nephropathy revisited: Early tubular cell changes and glomerulopathy in diabetic mice overexpressing human aldose reductase

Aims/Introduction:  The polyol pathway has long been involved in the pathogenesis of diabetic nephropathy. It remains still unclear, however, how the polyol pathway is implicated in this process. We explored the effects of the enhanced polyol pathway on renocortical tubular cells and glomeruli in experimentally-induced diabetes.

MATERIALS AND METHODS

  Transgenic mice (Tg) overexpressing human aldose reductase were made diabetic by streptozotocin and followed for 8 weeks. Renocortical pathology, expressions of tonicity-responsive enhancer binding protein (TonEBP) and carboxymethyllysine of advanced glycation end-products, were examined. Wild-type non-transgenic mice (Wt) were also made diabetic and served as controls.

RESULTS

  Diabetic Tg showed augmented expression of TonEBP in renocortical tubular cells with vacuolated degenerative changes. These structural changes were associated with pronounced deposition of carboxymethyllysine. There was a significant increase in kidney weight, glomerular size, and mesangial area in diabetic animals and there was a trend for more severe changes in these measures in diabetic transgenic mice compared with those in control diabetic mice. Treatment with aldose reductase inhibitor significantly prevented polyol accumulation, mesangial expansion and expressions of TonEBP and carboxymethyllysine in diabetic Tg, but its effects on the renal structure were equivocal in control diabetic Wt.

CONCLUSIONS

  Our findings suggest that tubuloglomerular change might contribute to early diabetic nephropathy under the influence of the enhanced polyol pathway. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00071.x, 2010).

Neuropathy induced by exogenously administered advanced glycation end-products in rats

Aims/Introduction:  Advanced glycation end‐products (AGE) have been implicated in the development of diabetic neuropathy. It still remains unknown, however, how AGE cause functional and structural changes of the peripheral nerve in diabetes. To explore the role of AGE in diabetic neuropathy, we examined the peripheral nerve by injecting AGE into normal Wistar rats.

Materials and Methods:  Young, normal male Wistar rats were injected intraperitoneally (i.p.) daily for 12 weeks with purified AGE prepared by incubating D‐glucose with bovine serum albumin (BSA). A control group received BSA alone. A group of rats given AGE were co‐treated with aminoguanidine (50 mg/kg/day, i.p.). Peripheral nerve function and structure, as well as nerve Na⁺,K⁺‐ATPase activity, were examined in these rats. Immunohistochemical expressions of 8‐hydroxy‐2′‐deoxyguanosine (8OHdG) and nuclear factor‐κB (NF‐κB)p65 were also examined.

Results:  Serum AGE levels were increased two to threefold in the AGE‐treated group compared with those in the BSA‐treated control group. AGE‐treated rats showed a marked slowing of motor nerve conduction velocity (MNCV) and decreased nerve Na⁺,K⁺‐ATPase activity compared with those in the BSA‐treated group. These changes were accompanied by intensified expressions of 8OHdG and NF‐κBp65 in endothelial cells and Schwann cells. Aminoguanidine treatment corrected MNCV delay, Na⁺,K⁺‐ATPase activity, and suppressed the expression of 8OHdG and NF‐κB, despite there being no influence on serum AGE levels.

Conclusions:  The results suggest that an elevated concentration of blood AGE might be one of the contributing factors to the development of neuropathic changes in diabetes.