Impairment of body mass reduction-associated activation of brown/beige adipose tissue in patients with type 2 diabetes mellitus.

Backgrounds/Objectives:The activity of brown/beige adipose tissue (B/BAT) is inversely proportional to body adiposity. Studies have shown that obese subjects submitted to distinct approaches aimed at reducing body mass present an increase of B/BAT activation. However, it is unknown if this beneficial effect of body mass reduction applies to patients with type 2 diabetes mellitus. In this study, we evaluated the impact of massive body mass reduction obtained as a consequence of bariatric surgery in the cold-induced activation of B/BAT in obese non-diabetic (OND) and obese diabetic (OD) subjects. SUBJECTS/METHODS: This is an observational study. Fourteen OND, 14 OD and 11 subjects were included in the study. All obese subjects were submitted to Roux-in-Y gastric bypass and measurements were performed before and 8 months after surgery. B/BAT was evaluated by (18F)-FDG-PET/CT scan and determination of signature transcript expression in specimens obtained in biopsies. RESULTS: Before surgery, mean B/BAT activity and the expression of signature transcripts were similar between OND and OD groups. Eight months after surgery, body mass reduction was similar between the obese groups. Nevertheless, the activity of B/BAT was increased in OND and unchanged in OD subjects. This effect was correlated with a more pronounced improvement of insulin resistance, as evaluated by the hyperinsulinemic, euglycemic clamp, in OND subjects as compared with OD subjects. CONCLUSIONS: Body mass reduction has a more efficient effect to induce the activation of B/BAT in non-diabetic than in diabetic subjects. This effect is accompanied by more pronounced insulin sensitivity and serine 473 phosphorylation of Akt in B/BAT of non-diabetic than in diabetic subjects.

Tumor necrosis factor-alpha levels in blood cord is directly correlated with the body weight of mothers.

BACKGROUND: Obesity has emerged as major public health problem leading to increased morbidity and mortality. Epidemiological studies indicate that in many regions of the world, children and teenagers are increasingly affected by obesity, which contributes for a pessimistic projection for the near future. Maternal obesity has been implicated in metabolic disorders of the offspring, but there are no biological markers that can be detected early on life that predict the development of obesity in the offspring. OBJECTIVE: To evaluate the expression of inflammatory markers in the umbilical cord blood of babies of mothers with obesity/overweight, and correlate these markers with the body weight at age 9 months. METHODS: Anthropometric data of mothers and babies were obtained during prenatal evaluation, at birth and 9 months after birth. Cord blood was collected during delivery of 54 babies from mothers with obesity/overweight and of 50 babies from lean mothers. Tumour necrosis factor-alpha (TNF-α), transforming growth factor 1 beta, monocyte chemoattractant protein-1 and 2 (MCP-1/MCP-2) were determined in serum samples using enzyme-linked immunosorbent assay methods. Correlations were evaluated using the Spearman correlation coefficient, and comparisons were evaluated using the non-parametric Mann-Whitney U-test. RESULTS: Cord blood TNF-α was positively correlated with maternal body mass index. There was an inverse correlation between cord blood transforming growth factor 1 beta and baby body weight at birth. There was no biological marker that predicted body weight at age 9 months. CONCLUSION: Although we have not found a biological marker to predict increased body weight at 9 months of age, the study shows that maternal obesity exposes the baby to higher TNF-α level in the early stages of life, and this can affect metabolic and inflammatory parameters during adulthood.

Hypothalamic AMPK activation blocks lipopolysaccharide inhibition of glucose production in mice liver.

Endotoxic hypoglycaemia has an important role in the survival rates of septic patients. Previous studies have demonstrated that hypothalamic AMP-activated protein kinase (hyp-AMPK) activity is sufficient to modulate glucose homeostasis. However, the role of hyp-AMPK in hypoglycaemia associated with endotoxemia is unknown. The aims of this study were to examine hyp-AMPK dephosphorylation in lipopolysaccharide (LPS)-treated mice and to determine whether pharmacological hyp-AMPK activation could reduce the effects of endotoxemia on blood glucose levels. LPS-treated mice showed reduced food intake, diminished basal glycemia, increased serum TNF-α and IL-1ß levels and increased hypothalamic p-TAK and TLR4/MyD88 association. These effects were accompanied by hyp-AMPK/ACC dephosphorylation. LPS-treated mice also showed diminished liver expression of PEPCK/G6Pase, reduction in p-FOXO1, p-AMPK, p-STAT3 and p-JNK level and glucose production. Pharmacological hyp-AMPK activation blocked the effects of LPS on the hyp-AMPK phosphorylation, liver PEPCK expression and glucose production. Furthermore, the effects of LPS were TLR4-dependent because hyp-AMPK phosphorylation, liver PEPCK expression and fasting glycemia were not affected in TLR4-mutant mice. These results suggest that hyp-AMPK activity may be an important pharmacological target to control glucose homeostasis during endotoxemia.

Defective regulation of adipose tissue autophagy in obesity.

OBJECTIVES: Autophagy is a highly regulated process that has an important role in the control of a wide range of cellular functions, such as organelle recycling, nutrient availability and tissue differentiation. A recent study has shown an increased autophagic activity in the adipose tissue of obese subjects, and a role for autophagy in obesity-associated insulin resistance was proposed. Body mass reduction is the most efficient approach to tackle insulin resistance in over-weight subjects; however, the impact of weight loss in adipose tissue autophagy is unknown. SUBJECTS: Adipose tissue autophagy was evaluated in mice and humans. RESULTS: First, a mouse model of diet-induced obesity and diabetes was maintained on a 15-day, 40% caloric restriction. At baseline, markers of autophagy were increased in obese mice as compared with lean controls. Upon caloric restriction, autophagy increased in the lean mice, whereas it decreased in the obese mice. The reintroduction of ad libitum feeding was sufficient to rapidly reduce autophagy in the lean mice and increase autophagy in the obese mice. In the second part of the study, autophagy was evaluated in the subcutaneous adipose tissue of nine obese-non-diabetic and six obese-diabetic subjects undergoing bariatric surgery for body mass reduction. Specimens were collected during the surgery and approximately 1 year later. Markers of systemic inflammation, such as tumor necrosis factor-1α, interleukin (IL)-6 and IL-1ß were evaluated. As in the mouse model, human obesity was associated with increased autophagy, and body mass reduction led to an attenuation of autophagy in the adipose tissue. CONCLUSION: Obesity and caloric overfeeding are associated with the defective regulation of autophagy in the adipose tissue. The studies in obese-diabetic subjects undergoing improved metabolic control following calorie restriction suggest that autophagy and inflammation are regulated independently.

Cerebrospinal fluid xenin levels during body mass reduction: no evidence for obesity-associated defective transport across the blood-brain barrier.

CONTEXT: Recent studies have shown that xenin can act in the hypothalamus, reducing food intake through a leptin- and melanocortin system-independent mechanism. OBJECTIVE: To evaluate the impact of body mass reduction on the blood and cerebrospinal fluid (CSF) levels of xenin. DESIGN AND SETTING: Thirteen obese patients (11 women) selected for roux-in-Y gastric bypass surgery were evaluated before and approximately 8 months after surgery. Xenin was determined in serum and CSF by radioimmunoassay. RESULTS: As compared with lean subjects, obese patients have increased blood levels of xenin, which reduce after surgery. There are significant correlations between blood xenin and blood leptin and insulin levels. CSF concentration of xenin is ∼10-fold lower than blood levels, and is significantly higher in obese subjects as compared with lean ones, returning to normal levels after body mass reduction. There is a significant linear correlation between CSF and blood levels of xenin. CONCLUSION: Xenin is present in the human CSF in a concentration ∼10-fold lower than the blood. Both blood and CSF xenin are correlated with blood levels of important markers of adiposity, leptin and insulin. The levels of CSF xenin are linearly correlated with blood xenin, independently of patient body mass, suggesting that either its transport across the blood-brain barrier is not saturated in the concentration range detected in this study or that there is a coordinated release of xenin from the periphery and the CNS.

Serum levels and mesenteric fat tissue expression of adiponectin and leptin in patients with Crohn's disease.

Crohn's disease (CD) is characterized by inflammation and an aetiology that is still unknown. Hypertrophy of mesenteric fat is a reflection of disease activity, as this fat covers the entire length of the affected area. Adipocytes synthesize leptin and adiponectin, adipocytokines responsible for pro- and anti-inflammatory effects. Therefore, we evaluated serum levels of adiponectin and leptin, as well as mesenteral expression of adiponectin in active CD and those in remission. Sixteen patients with ileocaecal CD followed at the Outpatient Clinic, Coloproctology Unit of University of Campinas Clinical Hospital, participated in the study. Analysis of serum adiponectin and leptin by enzyme-linked immunosorbent assay was performed in patients with active CD (ACD group), remission CD (RCD group) and in six healthy controls. Ten patients with active ileocaecal CD (FCD group) and eight patients with non-inflammatory disease selected for surgery were also studied. The specimens were snap-frozen and the expression of adiponectin was determined by immunoblot of protein extracts. Serum C-reactive protein levels were higher in the ACD group when compared to the others and no difference of body mass index was observed between the groups. Serum adiponectin was lower in the ACD group when compared to control, but no differences were seen when comparing the ACD and RCD groups. Mesenteric adiponectin expression was lower in the FCD group when compared to the FC group. Serum leptin was similar in all groups. The lower levels of serum and mesenteric adiponectin in active CD suggest a defective regulation of anti-inflammatory pathways in CD pathogenesis.

PGC1α gene Gly482Ser polymorphism predicts improved metabolic, inflammatory and vascular outcomes following bariatric surgery.

AIMS/HYPOTHESIS: Bariatric surgery is currently employed as an effective approach to treat class III obesity and class II obesity with co-morbidities. Unfortunately, the general anthropometric and metabolic outcomes of the surgery are not homogeneous, and defining the eligibility criteria that allow for a more precise prediction of the outcomes of this invasive procedure will refine the selection of patients. Here we tested the hypothesis that the Gly482Ser polymorphism of the ppargc1a gene would predict different outcomes following bariatric surgery. METHODS: Fifty-five patients (26 Gly/Gly and 29 Gly/Ser+Ser/Ser) selected for the Roux-en-Y gastric bypass according to the National Institutes of Health Consensus Statement criteria were followed up for 1 year, monitoring their anthropometric, metabolic and inflammatory parameters. RESULTS: Patients with the Gly482Ser polymorphism had significantly improved reductions in the waist/hip ratio, fasting blood glucose, C-reactive protein, blood leukocyte count, serum interleukin-6 and intima-media thickness of the carotid artery, as compared with Gly/Gly patients. CONCLUSIONS/INTERPRETATION: Thus, the Gly482Ser polymorphism may predict a more favorable metabolic and inflammatory outcome for obese patients submitted to bariatric surgery, leading to a reduced atherosclerotic risk.

Correlation between periodontal disease, inflammatory alterations and pre-eclampsia.

BACKGROUND AND OBJECTIVE: Several studies have hypothesized that periodontal disease may increase the risk of pre-eclampsia. The correlation between the two diseases would probably be based on hypertension-related cytokine release in the local periodontal environment. The aim of this study was to evaluate the association between periodontal disease and pre-eclampsia, and the correlation of the two conditions with interleukin-6 (IL-6) and tumor necrosis factor-α(TNFα) mRNA expression. MATERIAL AND METHODS: A case-control analysis of 116 pregnant women, 58 with pre-eclampsia (cases) and 58 normotensive pregnant women (controls) was performed. In addition to collection of socio-demographic data and periodontal evaluation, peripheral blood samples were collected for laboratory analysis of IL-6 and TNFα mRNA expression by real-time PCR. RESULTS: There was an association between periodontitis and pre-eclampsia (adjusted odds ratio 3.73; 95% confidence interval 1.32-10.58). Increased TNFα mRNA expression was observed in pre-eclamptic women; however, there was no correlation between periodontitis and systemic cytokine expression. In the case group, systemic cytokine mRNA levels were similar in pregnant women with and without periodontitis (means±SD): 0.73±0.24 vs. 0.82±0.38 for TNFα and 1.31±1.49 vs. 1.09±0.74 for IL-6, respectively. CONCLUSION: Periodontitis was clinically related to pre-eclampsia; however, the supposed mechanism that correlates the two diseases, i.e. a systemic inflammatory process involving cytokines TNFα and IL-6 in the presence of periodontal disease, could not be confirmed in this study.

A Interleucina 1-beta mostra uma ação protetora na fase aguda do modelo de epilepsia induzido pela pilocarpina / The il1β have a protective action in the acute phase of the pilocarpine-induced epilepsy model

INTRODUÇÃO: Existem contradições na literatura quanto aos efeitos dos genes il1β e il1rn nas epilepsias. Nosso objetivo foi avaliar os efeitos do silenciamento desses dois genes na fase aguda do modelo de epilepsia induzido pela pilocarpina. MÉTODOS: Para alterar a expressão dos genes il1β e il1rn utilizamos a técnica de interferência por RNA. RESULTADOS: Obtivemos taxas de silenciamento significativas para os dois genes no sistema nervoso central. Observamos efeitos fenotípicos significativos, incluindo a alteração na taxa de mortalidade dos animais 5 dias após a indução do modelo. CONCLUSÕES: A il1β parece exercer um papel protetor na fase aguda do modelo de epilepsia induzido pela pilocarpina.

INTRODUCTION: There is contradictory information regarding the of effects il1β and il1rn in epilepsy. We aimed to evaluate the effect of silencing both genes in the acute phase of the pilocarpine-induced epilepsy model. METHODS: We used RNA interference in order to achieve gene silencing. RESULTS: We obtained significant gene silencing in the central nervous system. In addition, we observed phenotypic effects including differences in mortality rates of animals 5 days after pilocarpine injections. CONCLUSION: Our results indicate that il1β seems to have a protective effect in the acute phase of the pilocarpine-induced epilepsy model.

TNF-α transiently induces endoplasmic reticulum stress and an incomplete unfolded protein response in the hypothalamus.

In diet-induced obesity, hypothalamic inflammation is triggered as an outcome of prolonged exposure to dietary fats. Toll-like receptor 4 (TLR4) activation plays a central role in this process, inducing endoplasmic reticulum stress and activating inflammatory cytokine gene transcription. Although saturated fatty acids can induce endoplasmic reticulum stress in the hypothalamus, it is unknown whether inflammatory cytokines alone can activate this mechanism. Here, rats were treated with TNF-α or lyposaccharide (LPS) and endoplasmic reticulum stress and unfolded protein response were evaluated by immunoblot and polymerase chain reaction (PCR). Activation of TLR4 by LPS was capable of inducing a complete endoplasmic reticulum stress and unfolded protein response through the PERK/eIF2α and IRE1α/XBP1 pathways. Conversely, TNF-α, injected either locally or systemically, was unable to induce a complete program of unfolded protein response, although the activation of endoplasmic reticulum stress was achieved to a certain degree. Thus, in the hypothalamus, the isolated action of TNF-α is insufficient to produce the activation of a complete program of unfolded protein response.

Type III hypersensitivity to insulin leading to leukocytoclastic vasculitis.

Here, we report the occurrence of leukocytoclastic vasculitis as an outcome of type III allergy to insulin in a patient with type II diabetes mellitus. The diagnosis was made on the basis of anatomo-pathological examination of a skin biopsy.

Activation of signal transducer and activator of transcription-1 (STAT-1) and differential expression of interferon-gamma and anti-inflammatory proteins in pelvic ileal pouches for ulcerative colitis and familial adenomatous polyposis.

Pouchitis after total rectocolectomy is the most common complication of ulcerative colitis (UC). The immunological mechanisms involved in the genesis of pouchitis are unclear. Therefore, we evaluated the inflammatory activity in normal ileal pouch mucosa by determining signal transducers and activators of transcription (STAT-1) activation and cytokine expression in patients operated for UC and familial adenomatous polyposis (FAP). Eighteen asymptomatic patients, who underwent total rectocolectomy and J pouch, were evaluated: nine with UC and nine with FAP. The activation of STAT-1 and cytokine expression were determined by immunoblot of total protein extracts from pouch mucosal biopsies. The absence of pouchitis was assessed by clinical, histological and endoscopic parameters, according to the Pouchitis Disease Activity Index. The patients were not receiving any medication. Analysis of variance (anova) and Tukey-Kramer's test were applied. The local ethical committee approved the study and informed consent was signed by all participants. STAT-1 activation was increased in UC when compared to FAP and controls (P < 0.05). Higher levels of interferon (IFN)-gamma expression were observed in UC patients when compared to the control group (P < 0.05), but were similar to FAP. In contrast, cytokine signalling (SOCS-3) and interleukin (IL)-10 expression were similar in all groups (P > 0.05). These findings could explain the higher susceptibility to this inflammatory complication in UC when compared to FAP. A tendency towards increased levels of IFN-gamma and STAT-1 in patients with UC, even without clinical and endoscopic evidence of pouchitis, was observed; studying inflammatory activity in asymptomatic ileal pouches may help understanding of the pathogenesis of pouchitis.

Inflammatory response in a rat model of gastroschisis is associated with an increase of NF-kappaB

Babies with gastroschisis have high morbidity, which is associated with inflammatory bowel injury caused by exposure to amniotic fluid. The objective of this study was to identify components of the inflammatory response in the intestine and liver in an experimental model of gastroschisis in rats. The model was surgically created at 18.5 days of gestation. The fetuses were exposed through a hysterotomy and an incision at the right of the umbilicus was made, exposing the fetal bowel. Then, the fetus was placed back into the uterus until term. The bowel in this model had macro- and microscopic characteristics similar to those observed in gastroschisis. The study was conducted on three groups of 20 fetuses each: gastroschisis, control, and sham fetuses. Fetal body, intestine and liver weights and intestine length were measured. IL-1â, IL-6, IL-10, TNF-á, IFN-ã and NF-kappaB levels were assessed by ELISA. Data were analyzed statistically by ANOVA followed by the Tukey post-test. Gastroschisis fetuses had a decreased intestine length (means ± SD, 125 ± 25 vs 216 ± 13.9; P < 0.005) and increased intestine weight (0.29 ± 0.05 vs 0.24 ± 0.04; P < 0.005). Intestine length correlated with liver weight only in gastroschisis fetuses (Pearson’s correlation coefficient, r = 0.518, P = 0.019). There were no significant differences in the concentrations of IL-1â, TNF-á or IFN-ã in the intestine, whereas the concentration of NF-kappaB was increased in both the intestine and liver of fetuses with gastroschisis. These results show that the inflammatory response in the liver and intestine of the rat model of gastroschisis is accompanied by an increase in the amount of NF-kappaB in the intestine and liver.

Aspirin attenuates insulin resistance in muscle of diet-induced obese rats by inhibiting inducible nitric oxide synthase production and S-nitrosylation of IRbeta/IRS-1 and Akt.

AIM/HYPOTHESIS: High-dose aspirin treatment improves fasting and postprandial hyperglycaemia in patients with type 2 diabetes, as well as in animal models of insulin resistance associated with obesity and sepsis. In this study, we investigated the effects of aspirin treatment on inducible nitric oxide synthase (iNOS)-mediated insulin resistance and on S-nitrosylation of insulin receptor (IR)-beta, IRS-1 and protein kinase B (Akt) in the muscle of diet-induced obese rats and also in iNos (also known as Nos2)-/- mice on high fat diet. METHODS: Aspirin (120 mg kg-1 day-1 for 2 days) or iNOS inhibitor (L-NIL; 80 mg/kg body weight) were administered to diet-induced obese rats or mice and iNOS production and insulin signalling were investigated. S-nitrosylation of IRbeta/IRS-1 and Akt was investigated using the biotin switch method. RESULTS: iNOS protein levels increased in the muscle of diet-induced obese rats, associated with an increase in S-nitrosylation of IRbeta, IRS-1 and Akt. These alterations were reversed by aspirin treatment, in parallel with an improvement in insulin signalling and sensitivity, as measured by insulin tolerance test and glucose clamp. Conversely, while aspirin reversed the increased phosphorylation of IkappaB kinase beta and c-Jun amino-terminal kinase, as well as IRS-1 serine phosphorylation in diet-induced obese rats and iNos -/- mice on high-fat diet, these alterations were not associated with the improvement of insulin action induced by this drug. CONCLUSIONS/INTERPRETATION: Our data demonstrate that aspirin treatment not only reduces iNOS protein levels, but also S-nitrosylation of IRbeta, IRS-1 and Akt. These changes are associated with improved insulin resistance and signalling, suggesting a novel mechanism of insulin sensitisation evoked by aspirin treatment.

Differential expression of pro-inflammatory cytokines and a pro-apoptotic protein in pelvic ileal pouches for ulcerative colitis and familial adenomatous polyposis.

BACKGROUND: Pouchitis after total rectocolectomy is among the most common complications of patients with ulcerative colitis (UC). However, its frequency is quite rare in patients with familial adenomatous polyposis (FAP). We evaluated the inflammatory and pro-apoptotic activity in endoscopically normal mucosa of the ileal pouch in patients with UC and FAP. METHODS: Twenty patients (10 with UC and 10 with FAP) with "J" pouch after total proctocolectomy were studied as were 10 normal controls. Biopsies were obtained from the mucosa of the pouch of UC and FAP patients and from the normal ileum of controls. The expression levels of TNF-alpha, IL-1beta, IL-6, IL-8 and phospho-BAD were determined by immunoblotting. Activated NFkappaB was evaluated by immuno-precipitation and immunoblotting for IkappaB kinase beta. RESULTS: Patients with UC had higher levels of IL-1beta, IL-6, IL-8 and TNF-alpha than patients with FAP. The level of TNF-alpha was higher in patients with UC than in patients with FAP; both patient groups had TNF-alpha levels higher than controls. Activation of NFkappaB was similar in all three groups. The expression of phospho-BAD was significantly lower in patients with FAP than in patients with UC. CONCLUSIONS: As compared with patients with FAP, patients with UC presented increased levels of some pro-inflammatory cytokines, even in the absence of clinical or endoscopic signs of pouchitis. Patients with FAP presented lower levels of pro-inflammatory proteins and of phospho-BAD. These findings may explain the higher rates of progression to pouchitis in UC patients, which could correlate with mucosal atrophy that occurs in inflamed tissue.

Circulating ghrelin concentrations are lowered by intracerebroventricular insulin.

AIMS/HYPOTHESIS: Ghrelin is a peptide that is mainly produced by the stomach and stimulates food intake, adiposity and weight gain. Previous studies have documented that plasma levels of ghrelin are reduced by insulin, but the mechanisms that mediate this effect are unclear. METHODS: To determine whether phosphatidylinositol 3-kinase (PI(3)K) and/or mitogen-activated protein kinase (MAPK) are involved in this insulin action, we tested the intracerebroventricular (i.c.v.) effect of specific inhibitors of PI(3)K (LY294002 and wortmannin) and MAPK (PD98059 and UO126) on the insulin-mediated reduction of ghrelin levels in rats. RESULTS: Intracerebroventricular treatment with insulin reduced ghrelin levels. Inhibition of PI(3)K specifically blocked the insulin-induced reduction in ghrelin concentration, whereas inhibition of MAPK had no effect on insulin-mediated actions. Moreover, pretreatment with i.c.v. PI(3)K inhibitors blocked the reduction of ghrelin levels after OGTT-induced hyperglycaemia and hyperinsulinaemia. CONCLUSIONS/INTERPRETATION: These data demonstrate that changes in insulin action in the central nervous system regulate circulating ghrelin levels and that PI(3)K is a specific mediator of this action.

Increased expression of advanced glycation end-products and their receptor, and activation of nuclear factor kappa-B in lacrimal glands of diabetic rats.

AIMS/HYPOTHESIS: To assess the involvement of the AGE-specific receptor (AGER, also known as RAGE) axis and nuclear factor kappa-B (NFKB, also known as NF-kappaB) activation in the development of lacrimal gland and tear film dysfunction in diabetes, the present study evaluated: (1) lacrimal gland and tear film alterations in diabetic rats; and (2) the expression of AGE, AGER and NFKB in ocular tissues of normoglycaemic and diabetic rats. MATERIALS AND METHODS: Diabetes was induced in male Wistar rats with intravenous streptozotocin. Tear secretion parameters were measured and NFKB expression was evaluated in lacrimal glands of control and diabetic rats by western blot. Immunohistochemistry with confocal microscopy was used to assess AGE, AGER and NFKB expression in lacrimal glands of both groups. RESULTS: Lacrimal gland weight and tear film volume were lower in diabetic than in control rats (p=0.01 and 0.02, respectively). IL1B and TNF concentrations in tears were higher in diabetic than in control rats (p=0.007 and 0.02, respectively). NFKB protein was identified in rat cornea, conjunctiva and lacrimal glands. AGE, AGER and NFKB expression were greater in lacrimal glands of diabetic than in those of control rats. CONCLUSIONS/INTERPRETATION: Diabetes induces significant alterations in rat lacrimal gland structure and secretion. The higher expression of AGE, AGER and NFKB in lacrimal glands of diabetic rats suggests that these factors are involved in signalling and in subsequent inflammatory alterations related to dry eye in diabetes mellitus.

Nuclear factor-kappaB and advanced glycation end-products expression in lacrimal glands of aging rats.

Advanced glycation end products (AGEs) increase with aging and induce signaling alterations that lead to inflammation and dysfunction in several tissues. Aging reduces function and insulin signaling in lacrimal glands (LGs). To evaluate whether AGE signaling and insulin secretion in LGs are altered in aging, 24- and 2-month-old male Wistar rats were compared. Immunohistochemistry with confocal microscopy was used to evaluate AGE, AGE receptor (RAGE) and nuclear factor-kappaB (NF-kappaB) expression in LGs. Basal tear secretion volume, insulin, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) levels in tears and LGs and peroxidase activity in LG tissue were measured. Insulin secretion from isolated LGs and pancreatic beta-cells was compared in the supernatant of aging and control rats in vitro by RIA after stimulation with 2.8-16.7 mM glucose, carbachol and KCl. AGE, RAGE and NF-kappaB expression was higher in LGs of aging compared with young rats. Basal tear secretion and peroxidase activity were significantly lower in the aging group (P=0.016 for both assays). IL-1beta and TNF-alpha levels were higher in tears of aging rats compared with young rats (P=0.007 and 0.05 respectively); however, even though aging rats were insulin-resistant (as confirmed by the insulin-tolerance test), the insulin levels in the tear film of aging and control rats were similar in vivo and in vitro. The higher expression of AGEs, RAGE and NF-kappaB in LGs of aging rats is accompanied by systemic insulin resistance and may be involved in LG and tear film alterations but does not affect insulin secretion in the tear film. These observations indicate that metabolic events may be related to LG and tear film dysfunctions in aging.

Non-obese adult onset diabetes with oral hypoglycemic agent failure: islet cell autoantibodies or reversible beta cell refractoriness?

Pancreatic ß cell function and insulin sensitivity, analyzed by the homeostasis model assessment, before and after 24 weeks of insulin therapy were studied and correlated with the presence of autoantibodies against ß cells (islet cell and anti-glutamic acid decarboxylase antibodies), in a group of 18 Brazilian lean adult non-insulin-dependent diabetes mellitus (NIDDM) patients with oral hypoglycemic agent failure (OHAF). Median fasting plasma glucose before and after insulin treatment was 19.1 and 8.5 mmol/l, respectively (P < 0.001); median HbA1c was 11.7 percent before vs 7.2 percent after insulin treatment (P < 0.001). Forty-four percent of the patients were positive (Ab+) to at least one autoantibody. Fasting C-peptide levels were lower in Ab+ than Ab- patients, both before (Ab+: 0.16 ± 0.09 vs Ab-: 0.41 ± 0.35 nmol/l, P < 0.003) and after insulin treatment (Ab+: 0.22 ± 0.13 vs Ab-: 0.44 ± 0.24 nmol/l, P < 0.03). Improvement of Hß was seen in Ab- (median before: 7.3 vs after insulin therapy: 33.4 percent, P = 0.003) but not in Ab+ patients (median before: 6.6 vs after insulin therapy: 20.9 percent). These results show that the OHAF observed in the 18 NIDDM patients studied was due mainly to two major causes: autoantibodies and ß cell desensitization. Autoantibodies against ß cells could account for 44 percent of OHAF, but Ab- patients may still present ß cell function recovery, mainly after a period of ß cell rest with insulin therapy. However, the effects of ß cell function recovery on the restoration of the response to oral hypoglycemic agents need to be determined

Prolactin-signal transduction in neonatal rat pancreatic islets and interaction with the insulin-signaling pathway.

During pregnancy, pancreatic islets undergo structural and functional changes in response to an increased demand for insulin. Different hormones, especially placental lactogens, mediate these adaptive changes. Prolactin (PRL) mainly exerts its biological effects by activation of the JAK2/STAT5 pathway. PRL also stimulates some biological effects via activation of IRS-1, IRS-2, PI 3-kinase, and MAPK in different cell lines. Since IRS-2 is important for the maintenance of pancreatic islet cell mass, we investigated whether PRL affects insulin-signaling pathways in neonatal rat islets. PRL significantly potentiated glucose-induced insulin secretion in islets cultured for 7 days. This effect was blocked by the specific PI 3-kinase inhibitor wortmannin. To determine possible effects of PRL on insulin-signaling pathways, fresh islets were incubated with or without the hormone for 5 or 15 min. Immunoprecipitation and immunoblotting with specific antibodies showed that PRL induced a dose-dependent IRS-1 and IRS-2 phosphorylation compared to control islets. PRL-induced increase in IRS-1/-2 phosphorylation was accompanied by an increase in the association with and activation of PI 3-kinase. PRL-induced IRS-2 phosphorylation and its association with PI 3-kinase did not add to the effect of insulin. PRL also induced JAK2, SHC, ERK1 and ERK2 phosphorylation in neonatal islets, demonstrating that PRL can activate MAPK. These data indicate that PRL can stimulate the IRSs/PI 3-kinase and SHC/ERK pathways in islets from neonatal rats.