Disturbance of lymphocyte circulation byPseudomonas aeruginosa infection in oxazolone-sensitized mice

Pseudomonas aeruginosa infection depresses contact sensitivity to oxazolone in mice. To test whether an altered lymphocyte circulation plays a role in this depression⁵¹Cr-labeled lymphocytes fromP. aeruginosa-infected and oxazolone-sensitized donors were injected intravenously into infected and sensitized recipients, and the radioactivity uptake of several organs was determine. The controls consisted of normal mice receiving labeled lymphocytes from normal donors. While the radioactivity recovered from the liver, spleen, and mesenteric lymph nodes was similar in the test and the control group, significantly more radioactivity was recovered from the draining lymph nodes of infected and sensitized recipients. The concentration of labeled lymphocytes from sensitized donors in the draining lymph nodes of sensitized recipients was 18% greater than that of the controls but 31% lower than that of infected and sensitized animals receiving cells from infected and sensitized donors.P. aeruginosa infection enhances lymphocyte entrapment within the draining lymph nodes of oxazolone-sensitized mice.     

Antibodies recognizing specific Mycobacterium avium subsp. paratuberculosis’s MAP3738c protein in type 1 diabetes mellitus children are associated with serum Th1 (CXCL10) chemokine

Recently Mycobacterium avium subsp. paratuberculosis (Map) was associated to type 1 diabetes mellitus (T1DM). In this study we investigated for Map presence in children affected by T1DM compared to healthy children. A pool of 212 sera from T1DM children at onset was compared to sera from 57 healthy children for humoral immune response towards the Map specific protein MAP3738c by ELISA. Serum concentrations of CXCL10 (pro-Th1) and CCL2 (pro-Th2) chemokines were also measured in both sera pool. Results showed that T1DM children had a stronger seropositivity towards MAP3738c protein compared to healthy children. Data highlighted also the correlation between serum activity of T1DM patients towards the specific protein of Map and the increase of CXCL10 concentration if compared to non-diabetic subjects. In conclusion, an immune response to Map in T1DM patients at onset was observed and this may indicate a role of the bacterium in triggering or precipitating the disease.     

Identification and molecular characterization of the RNA polymerase-binding motif of infectious bursal disease virus inner capsid protein VP3

Infectious bursal disease virus (IBDV), a member of the Birnaviridae family, is the causative agent of one of the most important infectious poultry diseases. Major aspects of the molecular biology of IBDV, such as assembly and replication, are as yet poorly understood. We have previously shown that encapsidation of the putative virus-encoded RNA-dependent RNA polymerase VP1 is mediated by its interaction with the inner capsid protein VP3. Here, we report the characterization of the VP1-VP3 interaction. RNase A treatment of VP1- and VP3-containing extracts does not affect the formation of VP1-VP3 complexes, indicating that formation of the complex requires the establishment of protein-protein interactions. The use of a set of VP3 deletion mutants allowed the mapping of the VP1 binding motif of VP3 within a highly charged 16-amino-acid stretch on the C terminus of VP3. This region of VP3 is sufficient to confer VP1 binding activity when fused to an unrelated protein. Furthermore, a peptide corresponding to the VP1 binding region of VP3 specifically inhibits the formation of VP1-VP3 complexes. The presence of Trojan peptides containing the VP1 binding motif in IBDV-infected cells specifically reduces infective virus production, thus showing that formation of VP1-VP3 complexes plays a critical role in IBDV replication.     

A model of glucose kinetics and their control by insulin,compartmental and noncompartmental approaches

Compartmental and noncompartmental models are used to quantify, from multiple steady-state tracer experiments, glucose kinetics and the effect of insulin upon them. Some aspects of experiment design are discussed. A physiological three-compartment model of glucose kinetics is proposed which provides a new quantitative picture of insulin control of glucose metabolism. Noncompartmental modeling is shown to have structural errors which prevent physiological insight. Compartmental models make a better use of the informational content of kinetic data, even if more demanding both in terms of modeling and computational effort and in terms of physiological thinking.     

TLR4-mediated survival of macrophages is MyD88 dependent and requires TNF-alpha autocrine signalling

Modulation of macrophage survival is a critical factor in the resolution of inflammatory responses. Exposure to LPS protects innate immune cells against apoptosis, although the precise pathways responsible for prolongation of macrophage survival remain to be fully established. The goal of this study was to characterize the mechanism of TLR4-mediated survival of murine bone marrow-derived macrophages upon M-CSF withdrawal in more detail. Using a combination of knockout mice and pharmacological inhibitors allowed us to show that TLR4 and TLR2 stimulation promotes long-term survival of macrophages in a MyD88-, PI3K-, ERK-, and NF-kappaB-dependent manner. LPS-induced long-term, but not short-term, survival requires autocrine signaling via TNF-alpha and is facilitated by a general cytoprotective program, similar to that mediated by M-CSF. TLR4-mediated macrophage survival is accompanied by a remarkable up-regulation of specific cell surface markers, suggesting that LPS stimulation leads to the differentiation of macrophages toward a mixed macrophage/dendritic cell-like phenotype.     

Circulating chemokine (CXC motif) ligand (CXCL)9 is increased in aggressive chronic autoimmune thyroiditis, in association with CXCL10

Chemokine (CXC motif) ligand (CXCL)9 (CXCL9) has been shown to be involved in autoimmune thyroid disorders, however no data are present about CXCL9 circulating levels in chronic autoimmune thyroiditis (AT) vs controls. Serum CXCL9 (and for comparison CXCL10) has been measured in patients with AT vs normal control and nontoxic multinodular goiter, and this parameter has been related to the clinical phenotype. For this study we selected 189 consecutive patients with newly diagnosed AT, 63 euthyroid controls, 30 patients with nontoxic multinodular goiter. The three groups were similar in gender distribution and age; 26% of AT patients had subclinical hypothyroidism. Serum CXCL9 was significantly higher in AT (148±110 pg/mL) than in controls (71±34 pg/mL) or patients with multinodular goiter (87±35 pg/mL) (p<0.0001). Among AT patients, CXCL9 levels were significantly higher in patients older than 50 years, those with a hypoechoic ultrasonographic pattern or with hypothyroidism. Also CXCL10 was confirmed to be associated with AT, overall in presence of hypothyroidism. In a multiple linear regression model of CXCL9 (ln[pg/mL]) vs age, thyroid volume, TSH, AbTg, AbTPO, hypoechoic pattern, the presence of hypervascularity, and CXCL10 (ln[pg/mL]), only TSH and CXCL10 (ln[pg/mL]) were significantly related to serum CXCL9 levels. We show that circulating CXCL9 is increased in patients with aggressive thyroiditis and hypothyroidism. A strong relation between circulating CXCL9 and CXCL10 has been first shown, underlining the importance of a T helper 1 immune attack in the initiation of AT.     

Characterization of beta-cell function impairment in first-degree relatives of type 2 diabetic subjects: modeling analysis of 24-h triple-meal tests

To investigate early secretory defects in prediabetes, we evaluated beta-Cell function and insulin sensitivity (M value, by euglycemic clamp) in 26 normotolerant first-degree relatives of type 2 diabetic patients (FDR) and 17 age- and weight-matched control subjects. beta-Cell function was assessed by modeling analysis of glucose and C-peptide concentrations measured during 24 h of standardized living conditions. Fasting and total insulin secretion (ISR) were increased in FDR, as was ISR at a reference 5 mM glucose level (ISR5, 107 +/- 6 vs. 87 +/- 6 pmol x min(-1) x m(-2), P < 0.05). ISR5 was inversely related to M in controls (ISR5 = k/M1.23, rho = -0.74, P < 0.005) but not in FDR; when M was accounted for (by calculating a compensation index ISR5 x M1.23), compensation for insulin resistance was impaired in FDR (10.8 +/- 1.0 vs. 13.4 +/- 0.6 units, P < 0.05). Potentiation of ISR, expressing relative transient increases in glucose-stimulated ISR during meals, was impaired in FDR (1.29 +/- 0.08 vs. 1.62 +/- 0.08 during 1st meal, P < 0.02). Moreover, the potentiation time course was related to glucose-dependent insulin-releasing polypeptide (GIP) concentrations in both groups, and the sensitivity of potentiation to GIP derived from this relationship tended to be impaired in FDR. Compensation index, potentiation, and sensitivity to GIP were interrelated parameters (P < 0.05 or less). beta-Cell function parameters were also related to mean 24-h glucose levels (r2 = 0.63, P < 0.0001, multivariate model). In conclusion, although in absolute terms ISR is increased in insulin-resistant FDR, beta-cell function shows a cluster of interrelated abnormalities involving compensation for insulin resistance, potentiation, and sensitivity to GIP, suggesting a beta-cell defect in the amplifying pathway of insulin secretion.     

Fasting-based estimates of insulin sensitivity in overweight and obesity: a critical appraisal

Objective: To identify simple methods to estimate the degree of insulin resistance. Research Methods and Procedures: The performance of a wide range of fasting‐based index estimates of insulin sensitivity was compared by receiver operating characteristic analysis (area under curves and their 95% confidence intervals) against the M value from euglycemic insulin clamp studies collected in the San Antonio (non‐Hispanic whites and Hispanic residents of San Antonio, TX) and European Group for the Study of Insulin Resistance (non‐diabetic white Europeans) databases (n = 638). Results: Insulin resistance differed substantially between lean (BMI < 25 kg/m²), overweight or obese (BMI ≥ 25 kg/m²), and type 2 diabetic individuals. Estimates of insulin resistance were, therefore, assessed in each group separately. In the overweight and obese subgroup (n = 302), the receiver operating characteristic performance of fasting‐based indices varied from 0.72 (0.62 to 0.82), in the case of the insulin/glucose ratio, to 0.80 (0.72 to 0.88) in the case of Belfiore free fatty acids. One superior method could not be identified; the confidence intervals overlapped, and no statistically significant differences emerged. All indices performed better when using the whole study population, with fasting plasma insulin, homeostatic model assessment, insulin/glucose ratio, quantitative insulin sensitivity check index, glucose/insulin ratio, Belfiore glycemia, revised quantitative insulin sensitivity check index, McAuley index, and Belfiore free fatty acids showing area under curves of 0.83, 0.90, 0.66, 0.90, 0.66, 0.90, 0.85, 0.83, and 0.86, respectively, because of the inclusion of very insulin sensitive (lean) and very insulin resistant cases (diabetic subjects). Discussion: In conclusion, a superior fasting‐based index estimate to distinguish between the presence and absence of insulin resistance in overweight and obesity could not be identified despite the use of the large datasets.