Patients with type 1 diabetes mellitus have impaired IL-1ß production in response to Mycobacterium tuberculosis.

Patients with diabetes mellitus have an increased risk of developing tuberculosis. Although the underlying mechanism is unclear, evidence suggests a role for chronic hyperglycaemia. We examined the influence of hyperglycaemia on Mycobacterium tuberculosis-induced cytokine responses in patients with type 1 diabetes mellitus (T1D). Peripheral blood mononuclear cells (PBMCs) from 24 male T1D patients with sub-optimal glucose control [HbA1c > 7.0% (53 mmol/L)] and from 24 age-matched male healthy controls were stimulated with M. tuberculosis lysate. Cytokine analysis, assessment of aerobic glycolysis, receptor recognition and serum cross-over experiments were performed to explore the mechanistic differences. PBMCs from T1D patients produced less bioactive interleukin (IL)-1ß in response to M. tuberculosis. IL-6 and interferon (IFN)-γ production trended towards a decrease, whilst other cytokines such as tumour necrosis factor (TNF)-α, IL-17 and IL-1Ra were normal. The decrease in cytokine production was not correlated to HbA1c or plasma glucose levels. Cross-over serum experiments did not alter the cytokine profile of T1D or control patients, arguing for an intrinsic cellular defect. Cellular metabolism and the expression of M. tuberculosis-related pattern recognition receptors (PRRs) such as TLR2, TLR4 and NOD2 did not differ between T1D patients and healthy controls. Compared to matched controls, T1D patients have a reduced capacity to produce pro-inflammatory cytokines in response to M. tuberculosis. The impaired IL-1ß production in T1D patients may contribute to the increased susceptibility to tuberculosis. This effect appears not to be related to prevailing glucose levels but to an intrinsic cellular deficit.

Start of insulin therapy in patients with type 2 diabetes mellitus promotes the influx of macrophages into subcutaneous adipose tissue.

AIMS/HYPOTHESIS: Insulin therapy in patients with type 2 diabetes mellitus is accompanied by weight gain characterised by an increase in abdominal fat mass. The expansion of adipose tissue mass is generally paralleled by profound morphological and inflammatory changes. We hypothesised that the insulin-associated increase in fat mass would also result in changes in the morphology of human subcutaneous adipose tissue and in increased inflammation, especially when weight gain was excessive. METHODS: We investigated the effects of weight gain on adipocyte size, macrophage influx, and mRNA expression and protein levels of key inflammatory markers within the adipose tissue in patients with type 2 diabetes mellitus before and 6 months after starting insulin therapy. RESULTS: As expected, insulin therapy significantly increased body weight. At the level of the subcutaneous adipose tissue, insulin treatment led to an influx of macrophages. When comparing patients gaining no or little weight with patients gaining >4% body weight after 6 months of insulin therapy, both subgroups displayed an increase in macrophage influx. However, individuals who had gained weight had higher protein levels of monocyte chemoattractant protein-1, TNF-α and IL-1ß after 6 months of insulin therapy compared with those who had not gained weight. CONCLUSIONS/INTERPRETATION: We conclude that insulin therapy in patients with type 2 diabetes mellitus improved glycaemic control but also induced body weight gain and an influx of macrophages into the subcutaneous adipose tissue. In patients characterised by a pronounced insulin-associated weight gain, the influx of macrophages into the adipose tissue was accompanied by a more pronounced inflammatory status. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00781495. FUNDING: The study was funded by European Foundation for the Study of Diabetes and the Dutch Diabetes Research Foundation.

The Gln223Arg polymorphism in the leptin receptor is associated with familial combined hyperlipidemia.

OBJECTIVE: Familial combined hyperlipidemia (FCH) is characterized by elevated levels of total cholesterol (TC), triglycerides (TG) and apolipoprotein B (apo B) and is associated with premature cardiovascular disease (CVD). Other features of FCH are obesity and insulin resistance. Serum leptin levels have also been associated with obesity, insulin resistance and atherosclerosis. Leptin exerts its effect through the leptin receptor (LEPR). The aim of this study is to determine whether the Gln223Arg polymorphism in the LEPR gene contributes to FCH and its associated phenotypes. METHODS: The study population consists of 37 families, comprising 644 subjects, of whom 158 subjects were diagnosed as FCH. The FCH diagnosis was based on plasma TC and TG levels, adjusted for age and gender, and absolute apo B levels, according to our recently published nomogram. The Gln223Arg polymorphism was studied by restriction fragment length polymorphism-PCR. RESULTS: Carriers of one or two Arg alleles had an increased risk of FCH, compared to subjects homozygous for the Gln allele (OR=1.6 [95% CI 1.0-2.4]). A difference in high-density lipoprotein cholesterol (HDL-c) levels was present between carriers and non-carriers of an Arg allele, 1.21 vs 1.28 mmol/l, respectively (P=0.04), but no differences in obesity, insulin resistance and other lipid parameters were found. CONCLUSION: The Gln223Arg polymorphism in the LEPR gene is associated with FCH, which is supported by a significant association between HDL-c levels and the LEPR gene.

Toll-like receptor-4 Asp299Gly polymorphism does not influence progression of atherosclerosis in patients with familial hypercholesterolaemia.

BACKGROUND: Toll-like receptor-4 (TLR4) is a major receptor for inflammatory stimuli potentially involved in the pathogenesis of atherosclerosis, such as lipopolysaccharide (LPS) and heat-shock proteins. The Asp299Gly polymorphism of the TLR4 gene has been associated with a reduced intima-media thickness (IMT) of the common carotid artery in healthy individuals. We have investigated whether the presence of the Asp299Gly polymorphism in patients with familial hypercholesterolaemia (FH) has a similar protective effect, and whether it influences the effects of HMG-CoA reductase treatment. MATERIALS AND METHODS: A cohort of 293 FH patients and 200 healthy volunteers were genotyped for the presence of the Asp299Gly allele using polymerase chain reaction followed by restriction fragment length polymorphism analysis. Intima-media thickness measurements, inflammatory parameters and the effect of HMG-CoA reductase inhibitors were compared between the patients with and without Asp299Gly allele. RESULTS: The Asp299Gly allele was present in 10.6% of the FH patients and 11.0% of the healthy individuals. Whereas the FH patients carrying the Asp299Gly allele displayed a reduced absolute IMT value compared with the FH patients carrying the wild-type allelle, the difference did not reach statistical significance. In addition, the effect of treatment with HMG-CoA reductase inhibitors was not influenced by the presence of Asp299Gly allele. CONCLUSION: The presence of the Asp299Gly allele of the TLR4 gene does not seem to exert a major influence on the progression of atherosclerosis in patients with FH.

Effect of glutathione S-transferase M1 genotype on progression of atherosclerosis in lifelong male smokers.

We hypothesize that smokers with the null genotype for GSTM1 (GSTM1-0), who thus lack the detoxification enzyme glutathione S-transferase mu-1, develop atherosclerosis at an increased rate compared to smokers with the positive genotype (GSTM1-1). We used data from a 2-year randomized placebo-controlled trial on the effect of vitamin E on atherosclerosis among 189 male smokers. Progression of atherosclerosis was measured by 2-year change of the common carotid intima media thickness (CCA-IMT) as measured by B-mode ultrasonography. The frequency of GSTM1-0 genotype was 0.5 in both the placebo and the vitamin E group. Smokers with GSTM1-0 genotype had a tendency to higher baseline CCA-IMT values than those with GSTM1-1 (0.97 versus 0.92 mm, P=0.09). Within the placebo group, more CCA-IMT progression was found for smokers with the GSTM1-0 than for smokers with the GSTM1-1 genotype after adjustment for baseline IMT and major CVD risk factors (0.050 versus -0.002 mm, P=0.046). In the vitamin E group no effect of GSTM1 genotype on atherosclerosis progression was found. Overall, smokers with GSTM1-0 genotype had a higher mean 2-year progression compared to those with GSTM1-1 as shown by a difference in increase of 0.042 mm (95% CI 0.006; 0.078, P=0.02). In conclusion, our data suggest that smokers lacking the detoxifying enzyme GST mu-1 develop progression of atherosclerosis at an increased rate.

Posttranscriptional down-regulation of tumor necrosis factor-alpha and interleukin-1beta production in acute meningococcal infections.

The regulation of tumor necrosis factor-alpha (TNF) and interleukin-1beta (IL-1beta) production was studied in patients with meningococcal disease. Circulating TNF and IL-1beta normalized within 1 day. TNF mRNA and IL-1beta mRNA in white blood cells decreased over 3-4 days. During the acute stage, TNF and IL-1beta production in stimulated whole blood cultures was down-regulated. After 4-5 days, this production was restored. The down-regulation was unlikely to be caused by circulating IL-6 and IL-10, as these cytokines normalized within 2-3 days. TNF mRNA in stimulated cultures during the acute stage, with down-regulated production, did not differ from that at recovery, with restored production. In contrast, the down-regulated production of IL-1beta was associated with significantly lower IL-1beta mRNA levels. Thus, TNF and IL-1beta production are differentially regulated. Whereas TNF production is regulated posttranscriptionally, IL-1beta production is also regulated at the mRNA level.

A semi-quantitative reverse transcriptase polymerase chain reaction method for measurement of MRNA for TNF-alpha and IL-1 beta in whole blood cultures: its application in typhoid fever and exentric exercise.

Whole blood cultures are used to study cytokine stimulation and release ex vivo. In the present study this method was compared with a more direct approach and a quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was used to assess mRNA expression for IL-1 beta and tumour necrosis factor alpha (TNF-alpha) and mRNA in whole blood. Stimulation of whole blood from normal donors with lipopolysaccharide (LPS) at various time intervals showed a parallel rise of immunogenic IL-1 beta and TNF-alpha as well as a rise of mRNA expression for IL-1 beta and TNF-alpha with peak levels for IL-1 beta after 4-6 h stimulation and for mRNA TNF-alpha expression after 2 h stimulation. These methods were used to explore cytokine production during the course of typhoid fever and after a 5 km run. In both conditions circulating cytokine concentrations were not influenced, but the TNF-alpha and IL-1 beta mRNA gene expression in circulating whole blood cells was increased in patients with typhoid fever. The LPS-stimulated production of TNF-alpha and IL-1 beta was decreased in both but there was no change for the mRNA content in whole blood for these cytokines. These findings demonstrate that RT-PCR is an attractive method to study the gene expression of cytokines in whole blood, an increased TNF-alpha and IL-1 beta gene expression is present in typhoid fever, and that the LPS stimulated downregulation of cytokines in exercise and typhoid fever may be mediated by post-transcriptional processes.

A case of hyperalphalipoproteinemia associated with albumin complexing.

We present a 3 year follow up of a new type of hyperalphalipoproteinemia with stable high density lipoprotein (HDL) concentrations around 6.0 mmol/l in a female with persistently elevated erythrocyte sedimentation rate (ESR). By density gradient ultracentrifugation, next to the intensively colored HDL2-fraction, an additional band between HDL3 and the serum proteins was seen consistently. The patient's plasma contained an unique complex of albumin with apoprotein A-I. Her IgM was 3- to 4-fold elevated was not complexed to HDL. Familial forms of hyperalphalipoproteinemia could be excluded. As a presumed reason for the existence of the HDL-albumin complex we found that the patient's post-heparin plasma lipoprotein lipase activity was over 2-fold increased, while that of hepatic lipase was over 2-fold decreased: no common cause for the existence of the albumin complex and the increased concentration of IgM was found.

Indications for the presence of circulating peroxidized low density lipoproteins in WHHL rabbits treated with antioxidants.

Low density apolipoprotein (apo) B-100 in homozygous WHHL rabbits appears heterogeneous on SDS-PAGE. At least four high molecular weight apolipoproteins were identified in contrast to the uniform apo B-100 band in the very low density lipoprotein (VLDL) fraction of WHHL-homozygotes and the apo B containing lipoproteins present in WHHL heterozygotes or New Zealand White rabbits. We studied whether these aberrations in homozygote WHHL-LDL were due to physical changes induced by lipid peroxidation. Therefore we treated WHHL rabbits for 28 days with a standard dose of 1% probucol or with a dose of 0.1% vitamin E and studied the parameters indicating lipid peroxidation in circulating LDL and in vitro in relation to its antioxidant content. The LDL of probucol-fed rabbits appeared completely resistant against oxidation in vitro with Cu2+ ions. LDL fluorescence and serum malondialdehyde concentrations, indicators of lipid peroxidized LDL, were lower than in the control WHHL rabbits. LDL of vitamin E-fed WHHL rabbits showed a twofold increased lag phase in comparison with LDL of control-fed animals; the maximal rate of oxidation was 2- to 3-fold lower while LDL fluorescence was between the values obtained in the two other groups. Malondialdehyde concentration in the vitamin E-treated group was also decreased when compared with controls. Despite these indications of increased lipid peroxidized circulating LDL in WHHL controls which could be reversed, at least partially, by the antioxidant treatments applied, these treatments were without effect on the physical structure of LDL as examined with agarose gel electrophoresis. Neither antioxidant treatment changed the typical apo B-100 pattern in WHHL-LDL.

Syllabic compression and speech intelligibility in hearing impaired listeners.

Syllabic compression has not been shown unequivocally to improve speech intelligibility in hearing-impaired listeners. This paper attempts to explain the poor results by introducing the concept of minimum overshoots. The concept was tested with a digital signal processor on hearing-impaired subjects. The results show that moderate syllabic compression may raise speech intelligibility, as long as overshoots are minimized and relatively short time constants are used. Frequency equalization also contributes to speech intelligibility.

Studies on the function of hepatic lipase in the cat after immunological blockade of the enzyme in vivo.

In order to investigate the in vivo function of hepatic lipase, cats were injected with anti-cat hepatic lipase antibodies which produced a complete and specific inhibition of heparin-releasable hepatic lipase. The cat was chosen as an animal model because it displays, like man, a relative deficiency of lipoprotein lipase compared to hepatic lipase and because the possession of two subfractions of high density lipoproteins, HDL2 and HDL3. In fasted cats no changes were observed in plasma triglycerides or phospholipids. In fed animals triglycerides increased considerably, indicating that hepatic lipase may have a function in the postprandial phase. In fat-loaded cats (6 g of fat/kg) triglycerides in the d less than 1.019 g/ml fraction increased from 4 h after the blockade due to accumulation of lipoproteins with pre-beta-mobility containing the apoproteins, apo B-100, apo E and apo A-I. Apo B-48 did not accumulate consistently. Phospholipids in the HDL2-fraction and those in the HDL3-fraction of the fat-loaded cats tended to increase and decrease from 6 and 9 h after the blockade, respectively. The absolute change in HDL2 phospholipids approximated that of HDL3-phospholipids. Overall, the density of HDL particles decreased, apparently secondary to the accumulation of apo A-I in the d less than 1.019 g/ml fraction. Our findings suggest that hepatic lipase is involved in the hydrolysis of a special class of apo A-I containing triglyceride-rich lipoproteins synthesised in the postprandial phase.

Evaluation of the dual-precipitation method for determination of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 in serum.

We compared the dual-precipitation method for measurement of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 (Gidez et al., J Lipid Res 1982;23:1206-33) with density-gradient ultracentrifugation in a swinging-bucket rotor (Demacker et al., Clin Chem 1983;29:656-63). The concentration of dextran sulfate 15,000 (DS) needed for optimal accuracy of the HDL2-chol and HDL3-chol values was established empirically. At a DS concentration of 0.87 g/L, the values for HDL2-chol as well as for HDL3-chol in 88 sera did not differ significantly from those obtained by ultracentrifugation. The precision of the method was satisfactory and was related to the concentration. Nevertheless, the dual-precipitation method lacks specificity inasmuch as it produces no fractions that contain only one HDL subfraction. HDL2 and HDL3 each contained an equivalent amount of cholesterol from the other. At increasing DS concentrations, some radiolabeled HDL3 appeared to have precipitated prior to complete precipitation of HDL2. This lack of specificity can be tolerated in large-scale epidemiological studies for screening, but not in small-scale intervention studies or in assay of clinical samples, where better accuracy is needed and ultracentrifugation is preferred.

Five methods for determining low-density lipoprotein cholesterol compared.

We evaluated three precipitation methods for determination of low-density lipoprotein cholesterol in serum and an indirect method involving the Friedewald formula (Clin Chem 18: 499-502, 1972) by comparison with results by ultracentrifugation. The results of all methods for 83 sera, including 59 hyperlipidemic type IIA, IIB, and IV sera agreed very well, at least for concentrations of serum triglycerides below 8 mmol/L. The accuracy of the Friedewald formula was confirmed in 285 other sera, including 66 sera with triglycerides content between 4.52 and 8.0 mmol/L. For type III sera, the precipitation methods produced similar values to those obtained with the Friedewald formula, all being much higher than the ultracentrifugation values. Density-gradient ultracentrifugation showed that the very-low-density lipoprotein remnants in type III sera almost completely coprecipitated with the low-density lipoproteins. The precipitation methods are not only accurate but also very precise (CV less than 5%); they can therefore be used in clinical laboratories to measure atherogenic low-density lipoproteins plus the remnants of very-low-density lipoproteins. However, when serum triglycerides and high-density lipoprotein cholesterol also are determined, the Friedewald formula is a reliable alternative.

Enzymic and chemical-extraction determinations of free fatty acids in serum compared.

We compared an enzymic test kit for determination of free fatty acids in serum (NEFA C-test, WAKO) with two modifications of a chemical extraction procedure, I (Clin. Chim. Acta 43: 317-320, 1973) and II (Clin. Chim. Acta 80: 327-332, 1977). All three procedures are specific for long- and medium-chain fatty acids. Short-chain fatty acids, some keto acids, and phospholipids did not interfere. Added fatty acid was quantitatively accounted for in all methods. Results obtained with the enzymic method and II did not differ significantly, whereas the results by I were about 10% lower. The concentration of NaCl in the copper reagent, but not the kind of solvent used to dissolve the standard, influenced the accuracy of the chemical methods. In the enzymic procedure, hydrolysis of triglycerides during incubation is unlikely to be the reason for too-high values. The precision of all three procedures is acceptable for use in clinical laboratories.

Stability of frozen liquid control sera for assay of cholesterol in high-density lipoprotein.

Liquid serum pools with low-, normal-, or above-normal concentration of high-density lipoprotein cholesterol were prepared by selection and dilution of sera having low lipoprotein content or by enrichment with concentrated high-density lipoprotein. Stability of the serum pools depended on storage conditions. On storage between -2 and -12 degrees C, the high-density lipoprotein cholesterol content decreased. At a constant temperature of -19 to -21 degrees C the concentrations remained stable for more than 18 months. The imprecision (CV) of the high-density lipoprotein cholesterol assay during this period as established with enzymic cholesterol analysis (Clin. Chem. 26: 1780-1786, 1980) of these serum pools was between 2.7 and 4.8% (n = 51). Serum pools prepared and stored as described are suitable for internal quality-control procedures. In external quality-control trials these sera may be superior to the commercially available lyophilized lipid control sera.

A study of the use of polyethylene glycol in estimating cholesterol in high-density lipoprotein.

We studied polyethylene glycol 6000 precipitation of lipoproteins other than high-density lipoproteins, before cholesterol is estimated in the supernate. Other lipoproteins in the supernatant fractions were detected by using rocket immunoelectrophoresis. A polyethylene glycol concentration of 75 g/L in the final mixture appeared to be optimal, and results agreed with those obtained by ultracentrifugation. Differences in serum pH, use of polyethylene glycol from different suppliers, or the presence of ethylenediaminetetraacetate resulted in values that differed significantly (by 40 to 60 mumol/L) from the reference values. Polyethylene glycol did not interfere in four different methods for determination of cholesterol. In combination with an enzymic cholesterol method, the polyethylene glycol method appeared to be very precise, even when lipemic sera (triglycerides up to 5.5 mmol/L) were analyzed that had diminished high-density lipoprotein cholesterol values. We consider this method a method of choice, especially when lipemic sera are tested and enzymic cholesterol analysis is used.