Diabetic complications and dysregulated innate immunity

Diabetes aggravates periodontitis by limiting repair through enhanced inflammation

Periodontitis is the most common lytic bone disease and one of the first clinical manifestations of diabetes. Diabetes increases the risk of periodontitis. The aim of the present study was to examine mechanisms by which diabetes aggravates periodontitis. Ligature-induced periodontitis was examined in Goto-Kakizaki rats with type 2 diabetes. A tumor necrosis factor (TNF)-specific-inhibitor, pegsunercept, was applied to diabetic rats after the onset of periodontal disease. Interferon-γ (IFN-γ), TNF-α, interleukin-1 β (IL-1β), fibroblast growth factor-2 (FGF-2), transforming growth factor beta-1 (TGFβ-1), bone morphogenetic protein-2 (BMP-2), and BMP-6 were measured by real-time RT-PCR, and histological sections were examined for leukocyte infiltration and several parameters related to bone resorption and formation. Inflammation was prolonged in diabetic rats and was reversed by the TNF inhibitor, which reduced cytokine mRNA levels, leukocyte infiltration, and osteoclasts. In contrast, new bone and osteoid formation and osteoblast numbers were increased significantly vs. untreated diabetic animals. TNF inhibition in diabetic animals also reduced apoptosis, increased proliferation of bone-lining cells, and increased mRNA levels of FGF-2, TGFβ-1, BMP-2, and BMP-6. Thus, diabetes prolongs inflammation and osteoclastogenesis in periodontitis and through TNF limits the normal reparative process by negatively modulating factors that regulate bone.

The bone marrow microenvironment contributes to type I diabetes induced osteoblast death

Type I diabetes increases an individual's risk for bone loss and fracture, predominantly through suppression of osteoblast activity (bone formation). During diabetes onset, levels of blood glucose and pro-inflammatory cytokines (including tumor necrosis factor α (TNFα)) increased. At the same time, levels of osteoblast markers are rapidly decreased and stay decreased chronically (i.e., 40 days later) at which point bone loss is clearly evident. We hypothesized that early bone marrow inflammation can promote osteoblast death and hence reduced osteoblast markers. Indeed, examination of type I diabetic mouse bones demonstrates a greater than twofold increase in osteoblast TUNEL staining and increased expression of pro-apoptotic factors. Osteoblast death was amplified in both pharmacologic and spontaneous diabetic mouse models. Given the known signaling and inter-relationships between marrow cells and osteoblasts, we examined the role of diabetic marrow in causing the osteoblast death. Co-culture studies demonstrate that compared to control marrow cells, diabetic bone marrow cells increase osteoblast (MC3T3 and bone marrow derived) caspase 3 activity and the ratio of Bax/Bcl-2 expression. Mouse blood glucose levels positively correlated with bone marrow induced osteoblast death and negatively correlated with osteocalcin expression in bone, suggesting a relationship between type I diabetes, bone marrow and osteoblast death. TNF expression was elevated in diabetic marrow (but not co-cultured osteoblasts); therefore, we treated co-cultures with TNFα neutralizing antibodies. The antibody protected osteoblasts from bone marrow induced death. Taken together, our findings implicate the bone marrow microenvironment and TNFα in mediating osteoblast death and contributing to type I diabetic bone loss.

Captopril and combination therapy of captopril and pentoxifylline in reducing proteinuria in diabetic nephropathy

Chronic kidney disease is a worldwide health problem. Type II diabetes mellitus is now a major cause of end stage renal disease. The effect of diabetes mellitus through the dysregulation of the innate immunity results in increased tumor necrosis factor-alpha. This can lead to an increasing protein trafficking through the glomerular capillary, which can have an intrinsic renal toxicity. Seventy-four patients with type II diabetes mellitus with overt proteinuria were included in the study. They were randomly assigned to two groups of 37 patients (group 1: captopril 25 mg three times a day, group 2: captopril 25 mg and pentoxifylline 400 mg each three times per day). In the course of the study, two patients were excluded from each group. Daily urinary protein excretion was assessed at baseline and at two and six months. The reduction of urinary protein to creatinine clearance ratio in group 2 was 15.16 points more than in group 1 from baseline to the end of the study (p = 0.001). The difference in reduction only started after two months of pentoxifylline use. The differences in HbA1c and duration of diabetes mellitus at baseline in the two groups had not adversely affected the outcome of the study. There was a modest decrease in systolic blood pressure in group 2 as well (p = 0.041). Combining an angiotensin-converting enzyme inhibitor and pentoxifylline can lead to a greater reduction in proteinuria.

Identification of diabetic nephropathy-selective proteins in human plasma by multi-lectin affinity chromatography and LC-MS/MS

PURPOSE

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus. Microalbuminuria has been established as a risk factor for the development of diabetic renal disease. Recently, microalbuminuria has been reported to have limitations in determining disease risk and predicting DN. Therefore, identification of more specific biomarkers for prediction of DN is needed.

EXPERIMENTAL DESIGN

When kidney damage is initiated, glycoprotein leakage into the blood may occur, thus altering the glycoproteome profile of the blood. Here, we have used a combined approach of glycoprotein enrichment of plasma with a proteomic analysis to discover potential DN biomarkers. We isolated glycoproteins from plasma provided by six type 2 diabetes control (DC) and six type 2 DN patients using multi-lectin affinity chromatography. Captured glycoproteins were resolved by 1-D PAGE and tryptic digests of isolated proteins were analyzed by LC-MS/MS.

RESULTS

From the comparative and semi-quantitative proteome analysis, we identified 13 up- and 14 down-regulated glycoproteins in DN plasma. Among the up-regulated glycoproteins, the levels of lumican, vasorin and retinol binding protein-4 were verified by Western blot analysis of individual plasma samples.

CONCLUSION AND CLINICAL RELEVANCE

Collectively, our findings show that biomarker discovery has considerable potential for predicting diabetic nephropathy in diabetic patients.

PTSD is associated with an excess of inflammatory immune activities

PURPOSE. Post-traumatic stress disorder (PTSD) is associated with inflammatory-related medical conditions. This review examines studies of immune function in individuals with PTSD to determine if excessive inflammation is associated with PTSD. CONCLUSIONS. Current studies suggest an excess of inflammatory actions of the immune system in individuals with chronic PTSD. High levels of inflammatory cytokines have also been linked to PTSD vulnerability in traumatized individuals. There is also evidence that excessive inflammation is in part due to insufficient regulation by cortisol. PRACTICE IMPLICATIONS. An excess of inflammatory immune activity may contribute to health declines in individuals with PTSD, and treating PTSD symptoms may reduce these risks.

Early effects of high glucose in retinal tissue cultures Renin-Angiotensin system-dependent and -independent signaling

The early effects of the diabetic milieu on retinal tissue and their relation to the Renin-Angiotensin system (RAS) activation are poorly known. Here we investigated RAS signaling in retinas explanted from adult rats exposed for 48 h to high glucose (HG), with or without the Angiotensin Converting Enzyme inhibitor enalaprilat, which blocks RAS. HG was observed to i) initiate a phosphotyrosine-dependent signaling cascade; ii) up-regulate Angiotensin(1) Receptor (AT(1)R); iii) activate src tyrosine kinase and increase phosphorylation of Pyk2, PLCgamma1 and ERK1/2; and iv) activate Akt and the transcription factor CREB. In the presence of enalaprilat, tyrosine phosphorylation signal and AT(1)R upregulation decreased and activation of PLCgamma1 and CREB reverted, showing their relation to RAS signaling. In line with Akt activation, no apoptosis or synapse degeneration was found. Müller glia was activated, but in a RAS-independent manner. Our results suggest that, in early phases of HG exposure, a pro-survival cell program may be induced in the retina.

Relationship between periodontal condition and plasma reactive oxygen metabolites in patients in the maintenance phase of periodontal treatment

BACKGROUND

The relationship between systemic antioxidative status and periodontal condition has been investigated in epidemiologic studies. However, little literature is available with regard to the correlation between systemic reactive oxygen species and periodontal condition. The purpose of this cross-sectional study was to investigate the relationship between plasma reactive oxygen metabolites (ROM) and periodontal condition in patients in the maintenance phase of periodontal treatment.

METHODS

Eighty-one subjects (mean age: 57.4 years) who had entered a periodontal maintenance program were examined for probing depth (PD) and clinical attachment level (CAL). Plasma levels of ROM and biologic antioxidant potential (BAP) were determined with a free radical electric evaluator.

RESULTS

The plasma level of ROM was positively correlated to mean CAL (r = 0.281; P = 0.011) and percentage of teeth with CAL > or =4 mm (r = 0.236; P = 0.034), but not mean PD (r = 0.196; P = 0.080). Logistic regression analysis showed that subjects with ROM levels >400 Carratelli units (CARR U) had significantly higher mean CAL compared to subjects with ROM < or =400 CARR U after adjusting for age, gender, and the number of teeth present (P = 0.011). However, the plasma level of BAP was not significantly correlated with the periodontal parameters.

CONCLUSIONS

A positive association was found between plasma oxidative status and CAL in patients in the maintenance phase of periodontal therapy. A systemic increase in oxidative stress may influence the rate of progression of periodontal disease.

Bone inflammation and altered gene expression with type I diabetes early onset

Type I diabetes is associated with bone loss and marrow adiposity. To identify early events involved in the etiology of diabetic bone loss, diabetes was induced in mice by multiple low dose streptozotocin injections. Serum markers of bone metabolism and inflammation as well as tibial gene expression were examined between 1 and 17 days post-injection (dpi). At 3 dpi, when blood glucose levels were significantly elevated, body, fat pad and muscle mass were decreased. Serum markers of bone resorption and formation significantly decreased at 5 dpi in diabetic mice and remained suppressed throughout the time course. An osteoclast gene, TRAP5 mRNA, was suppressed at early and late time points. Suppression of osteogenic genes (runx2 and osteocalcin) and induction of adipogenic genes (PPARgamma2 and aP2) were evident as early as 5 dpi. These changes were associated with an elevation of serum cytokines, but more importantly we observed an increase in the expression of cytokines in bone, supporting the idea that bone, itself, exhibits an inflammatory response during diabetes induction. This inflammation could in turn contribute to diabetic bone pathology. IFN-gamma (one of the key cytokines elevated in bone and known to be involved in bone regulation) deficiency did not prevent diabetic bone pathology. Taken together, our findings indicate that bone becomes inflamed with the onset of T1-diabetes and during this time bone phenotype markers become altered. However, inhibition of one cytokine, IFN-gamma was not sufficient to prevent the rapid bone phenotype changes.

Low cortisol, high DHEA, and high levels of stimulated TNF-alpha, and IL-6 in women with PTSD

Posttraumatic stress disorder (PTSD) has been associated with hypothalamic-pituitary-adrenal (HPA) axis and immune function alterations; however, few studies have simultaneously investigated these systems in participants with PTSD. In this study, HPA axis and immune function in 26 women with PTSD with and without major depressive disorder was compared to 24 traumatized controls and to 21 nontraumatized controls. Posttraumatic stress disorder was associated with low cortisol and higher levels of DHEA and greater production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) compared to traumatized and healthy controls. Women with PTSD and depression exhibited greater production of IL-6 and higher levels of dehydroepiandrosterone (DHEA) than those with PTSD, but without depression. These findings suggest dysregulated HPA axis and immune function in women with PTSD, and that comorbid depression may contribute to these abnormalities.