Toll-like receptors regulate B cell cytokine production in patients with diabetes

AIMS/HYPOTHESIS

Understanding cellular and molecular events in diabetes mellitus will identify new approaches for therapy. Immune system cells are important modulators of chronic inflammation in diabetes mellitus, but the role of B cells is not adequately studied. The aim of this work was to define the function of B cells in diabetes mellitus patients through focus on B cell responses to pattern recognition receptors.

METHODS

We measured expression and function of Toll-like receptors (TLRs) on peripheral blood B cells from diabetes mellitus patients by flow cytometry and multiplexed cytokine analysis. We similarly analysed B cells from non-diabetic donors and periodontal disease patients as comparative cohorts.

RESULTS

B cells from diabetes mellitus patients secrete multiple pro-inflammatory cytokines, and IL-8 production is significantly elevated in B cells from diabetic patients compared with those from non-diabetic individuals. These data, plus modest elevation of TLR surface expression, suggest B cell IL-8 hyperproduction is a cytokine-specific outcome of altered TLR function in B cells from diabetes mellitus patients. Altered TLR function is further evidenced by demonstration of an unexpected, albeit modest 'anti-inflammatory' function for TLR4. Importantly, B cells from diabetes mellitus patients fail to secrete IL-10, an anti-inflammatory cytokine implicated in inflammatory disease resolution, under a variety of TLR-stimulating conditions. Comparative analyses of B cells from patients with a second chronic inflammatory disease, periodontal disease, indicated that some alterations in B cell TLR function associate specifically with diabetes mellitus.

CONCLUSIONS/INTERPRETATION

Altered TLR function in B cells from diabetes mellitus patients increases inflammation by two mechanisms: elevation of pro-inflammatory IL-8 and lack of anti-inflammatory/protective IL-10 production.

Jak/STAT signaling is involved in the inflammatory infiltration of the kidneys in MRL/lpr mice

Cytokines are known to play an important role in the pathogenesis of lupus nephritis (LN) and the Jak/STAT (Janus kinase-signal transducer and activator of transcription factor) pathway is important in mediating signal transduction of cytokines. This study examined the pathogenic role of Jak/STAT signaling in LN. MRL/lpr mice were either treated with a selective Jak2 inhibitor tyrphostin AG490 or with vehicle alone from 12 weeks of age until being sacrificed at week 20. AG490 significantly inhibited the phosphorylation of Jak2 and STAT1 (p < 0.05). Compared with the vehicle-treated mice, AG490 treatment significantly reduced proteinuria, improved renal function and suppressed histological lesions of the kidneys and salivary glands (p < 0.05). AG490 treatment significantly inhibited the renal expression of monocyte chemotactic protein (MCP)-1, interferon (IFN)-gamma and class II MHC, which was accompanied by reduced renal infiltration of T cells and macrophages (p < 0.05). In addition, AG490 treatment resulted in a decrease in serum anti-double-stranded DNA (anti-dsDNA) antibody and attenuated the deposition of IgG and C3 in the kidneys (p < 0.05). This study demonstrated that Jak/STAT pathway is implicated in the progression of renal inflammation in MRL/lpr mice and targeting this pathway may provide a potential therapeutic approach for LN.

TUNEL and growth factor expression in the prefrontal cortex of Alzheimer patients over 80 years old

To elucidate factors underlying the increased risk of developing Alzheimers disease (AD) in older individuals, the prefrontal cortices of younger (58-79 years) and of older (over 80 years) AD patients were examined by silver impregnation, TUNEL assay and immunohistochemistry for hyperphosphorylated tau, LDH and two growth factors (BDNF, NGF). Quantitative data were compared with those of age-matched controls. TUNEL-positive cells were mainly located in superficial cortical layers of younger and in deeper layers of older AD patients. Their density was more than 5 times higher in older AD than in younger AD (p < or = 0.05), but apoptotic cell morphology was rarely seen. Significantly more neuronal somas were contacted by degenerating fibers both in younger and older AD cortices. Density of tau-immunoreactive cells, which were virtually absent in controls, was twice as high in older AD patients as in younger AD individuals (p < or = 0.05). In younger AD, TUNEL positive cells generally lacked tau immunoreaction, whereas in older AD, most cells were double-labeled for hyperphosphorylated tau and TUNEL (p < or = 0.05). Numerical density of BDNF-immunoreactive cells was significantly reduced by 20 percent in older AD patients, compared to both control individuals and younger AD patients, whereas density of NGF-positive cells was the same in all patient groups examined. The distinct differences between younger and older AD patients suggest a faster progression of AD in older patients.

Ecotoxicological study on sediments of Mai Po marshes, Hong Kong using organisms and biomarkers

Sediments from Mai Po Ramsar site, Hong Kong were in general shown to be highly toxic based on the results of four toxicity tests (Microtox solid-phase test, Daphnia mortality test, algal [Microcystis aeruginosa] growth inhibition test and ryegrass [Lolium perenne] seed germination/root elongation test). Sediment of the mudflat (which is open to Deep Bay, i.e., the pollution source) was the most toxic while sediment of gei wai 24g (an enclosed freshwater pond) was the least toxic. Results of biomarker studies (tilapia hepatic metallothionein; glutathione (GSH) and EROD activity using H4IIE rat hepatoma cell) were also concordant with those in the toxicity tests. Significant liner relationships (p<0.01) were found between GSH contents in the rat hepatoma cells and PAHs, OCPs contents in the sediment extracts. It is recommended that the present suite of bioassays is useful and is biologically relevant for future ecotoxicological studies focusing on similar wetlands.

Spontaneous acute tumor lysis syndrome as a cause of early deaths in short-term carcinogenicity studies using p53 +/- mice

Acute tumor lysis syndrome (ATLS) is a potentially lethal condition precipitated by the massive release of intracellular components such as nucleic acids, potassium, and phosphorus, following a rapid and widespread lysis of tumor cells. Herein, the authors describe the high incidence and characteristic histopathologic lesions of acute ATLS in p53-deficient mice used in 2 short-term carcinogenicity studies. ATLS was a frequent cause of early death in p53 (+/-) mice in these studies and was consistently associated with the presence of disseminated lymphoma and leukemia. Although a heavy tumor burden and leukemia were present in all affected mice, the absence of ATLS in other mice with equally severe lymphoma and leukemia indicates that these tumor burdens are necessary but insufficient to cause ATLS in mice. The hallmark histopathologic findings of ATLS in mice are the disseminated microemboli composed of nuclear and cytoplasmic debris derived from lysed tumor cells. The mechanical obstruction of capillary beds by these microemboli appeared to be the proximate cause of the early deaths of mice in these studies. Microemboli may contribute to the pathogenesis of acute renal failure and other clinical signs associated with ATLS in other species. Recognition of ATLS in laboratory animals is critical in studies intended to evaluate the efficacy and/or toxicity of anticancer treatments, where early deaths due to ATLS might otherwise be attributed to test article toxicity. Further studies on the role of microemboli in the pathogenesis of ATLS may elucidate pathogenetic mechanisms and lead to improved approaches to clinical management and treatment of this potentially lethal condition.

Increased hepatic and decreased urinary metallothionein in rats after cessation of oral cadmium exposure

We investigated the role of metallothionein (MT) in tissues after cessation of cadmium (Cd) exposure. Wistar rats of both genders were given CdCl(2) in drinking water at daily doses of 0, 2.5, 5.0 or 10.0 mg Cd/kg body-weight for 12 weeks. Half of the animals were then killed; the others were given Cd-free water for the following 16 weeks, i.e. until 28 weeks after start of the experiment (28-week rats). We observed dose-dependent increases in the levels of MT in the tissues of rats 12 weeks after beginning the experiment (12-week rats). After the exposure ceased, levels of MT in the 28-week rats changed in three ways: an increase in the liver, persistence in the kidney cortex and a decrease in the medulla, relative to those levels in their 12-week counterparts. Biomarkers of kidney dysfunction were determined to be urinary MT (UMT) and urinary N-acetyl-beta-D-glucosaminidase (UNAG). After 12 weeks, we observed dose-related statistically significant increases in UMT and UNAG in all of the Cd-exposed groups. A statistically significant decrease for UNAG between the 12- and 28-week rats occurred among males at the lowest Cd dose and for UMT in all of the Cd-exposed groups. The unchanged tissue levels of MT in the kidney cortex suggest that decreased UMT is a sign either of (i) decreased transport of Cd-MT from the liver via blood plasma to the renal tubules or (ii) increased tubular reabsorption and recovery of renal tubular function.

Clinical Applications and Acute Hepatotoxicity of Intravenous Amiodarone

This cross-sectional, retrospective study was designed to evaluate the current clinical applications and acute hepatotoxicity of intravenous amiodarone administration at a hospital in China. Clinical data were collected from 1214 patients receiving intravenous amiodarone treatment between October 2003 and September 2005. Baseline patient characteristics, drug indications, administration records and acute hepatotoxicity associated with the drug were examined. Amiodarone was used primarily in arrhythmic patients with obvious cardiac dysfunction. Atrial fibrillation and ventricular arrhythmia were the two most commonly treated dysfunctions. Incorrect indications and administration methods were also noted. Hepatotoxicity occurred in 12.6% of the patients, but was mild in most cases. Males showed a higher incidence of hepatotoxicity than females. The use of amiodarone was considered to be reasonable and standardized, but there was still considerable room for improvement, particularly in the standardization of administration guidelines. Intravenous amiodarone can cause hepatotoxicity and hepatic function tests should be performed soon after giving amiodarone intravenously.

Changes in bone mineral density 10 years after marked reduction of cadmium exposure in a Chinese population

The main focus of this study was to evaluate the long-term effects of Cd on forearm bone mineral density after the cessation of the ingestion of Cd-polluted rice. A total of 458 persons (294 women, 164 men) from three Cd exposure areas (low, moderately, and heavy) participated in this study. Those living in the moderate and heavy exposure areas ceased ingesting Cd-polluted rice (0.51 and 3.7mg/kg, respectively) in 1996 (10 years prior to present analysis). The participants completed a questionnaire and bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at the proximal radius and ulna. The changes and change percentage in forearm bone density and the prevalence of osteoporosis between 1998 and 2006 were used as markers of bone recovery. The Cd concentrations in urine (UCd) and blood (BCd) in 1998 were used as Cd exposure markers. The values of the BMD change and change percentage of groups in which UCd was above 5microg/g creatinine (microg/g crea) and BCd was above 10microg/L were significantly higher than those of the low-exposure groups (in women, p<0.001; in men, p>0.05). The BMD change and change percentage correlated positively with the UCd and BCd (in women, p<0.01; in men, p>0.05). Analysis of the Z-score revealed that the prevalence of osteoporosis in 2006 was higher than that in 1998 and increased along with the level of UCd and BCd in both women and men, especially for those subjects with the higher BCd [BCd>5microg/L, OR=3.45 (0.95-13.6); BCd>10microg/L, OR=4.51(1.57-13.54)] and UCd [UCd>10microg/g crea, OR=4.74 (1.82-12.81)] in women. It is concluded that decreasing dietary cadmium exposure at the population level is not associated with bone recovery at the individual level, and the adverse bone effects of Cd exposure persisted after the main source of Cd exposure had been blocked, especially in women.