Towards a role of interleukin-32 in atherosclerosis.

BACKGROUND: IL-32 has been previously shown to promote inflammation in rheumatoid arthritis patients and to contribute to IL-1ß-induced ICAM-1 as well as other proinflammatory cytokines synthesis in human umbilical endothelial cells (HUVECs). Given the high rate of atherosclerosis in RA, these observations suggest that IL-32 may be involved in the inflammatory pathways of atherosclerosis. METHODS: mRNA and protein levels of IL-32 were determined in human atherosclerotic arterial vessel wall tissue by quantitative real-time PCR and immunohistochemistry. HUVEC and M1/M2 macrophages were stimulated with proinflammatory cytokines and TLR ligands to assess IL-32 mRNA induction. Human THP1 macrophages were transduced with AdIL-32γ, to investigate induction of several proatherosclerotic mediators. Finally, aortas from IL-32γ transgenic mice were studied and compared with aortas from age-matched wild-type mice. RESULTS: IL-32 expression was detectable in human atherosclerotic arterial vessel wall, with the expression of IL-32ß and IL-32γ mRNA significantly enhanced. TLR3-ligand Poly I:C in combination with IFNγ were the most potent inducers of IL-32 mRNA expression in both HUVEC and M1/M2 macrophages. Adenoviral overexpression of IL-32γ in human THP1 macrophages resulted in increased production of CCL2, sVCAM-1, MMP1, MMP9, and MMP13. The IL-32γ transgenic mice chow a normal fat diet exhibited vascular abnormalities resembling atherosclerosis. CONCLUSIONS: IL-32 acts as a proinflammatory factor and may be implicated in the inflammatory cascade contributing to atherosclerosis. By promoting the synthesis of matrix metalloproteinases, it may further contribute to plaque instability. Further studies are warranted to investigate whether IL-32 may serve as a potential therapeutic target in fighting atherosclerosis.

The inflammasome-mediated caspase-1 activation controls adipocyte differentiation and insulin sensitivity.

Obesity-induced inflammation originating from expanding adipose tissue interferes with insulin sensitivity. Important metabolic effects have been recently attributed to IL-1ß and IL-18, two members of the IL-1 family of cytokines. Processing of IL-1ß and IL-18 requires cleavage by caspase-1, a cysteine protease regulated by a protein complex called the inflammasome. We demonstrate that the inflammasome/caspase-1 governs adipocyte differentiation and insulin sensitivity. Caspase-1 is upregulated during adipocyte differentiation and directs adipocytes toward a more insulin-resistant phenotype. Treatment of differentiating adipocytes with recombinant IL-1ß and IL-18, or blocking their effects by inhibitors, reveals that the effects of caspase-1 on adipocyte differentiation are largely conveyed by IL-1ß. Caspase-1 and IL-1ß activity in adipose tissue is increased both in diet-induced and genetically induced obese animal models. Conversely, mice deficient in caspase-1 are more insulin sensitive as compared to wild-type animals. In addition, differentiation of preadipocytes isolated from caspase-1(-/-) or NLRP3(-/-) mice resulted in more metabolically active fat cells. In vivo, treatment of obese mice with a caspase-1 inhibitor significantly increases their insulin sensitivity. Indirect calorimetry analysis revealed higher fat oxidation rates in caspase-1(-/-) animals. In conclusion, the inflammasome is an important regulator of adipocyte function and insulin sensitivity, and caspase-1 inhibition may represent a novel therapeutic target in clinical conditions associated with obesity and insulin resistance.

The effect of the initiation of renal replacement therapy on lipid profile and oxidative stress during the first 6 months of treatment.

BACKGROUND: Disturbed lipoproteins and increased oxidative stress are two of the "non-traditional" cardiovascular risk factors in chronic renal failure. There are very few prospective data of the influence of dialysis on these two factors. In the present study we investigated the effects of the initiation of both hemo- and peritoneal dialysis therapy on lipoproteins and parameters of LDL oxidation. METHODS: In this prospective cohort study, we assessed lipoproteins, plasma lipid peroxides and in vitro copper-induced LDL oxidation in 46 patients with end-stage renal disease prior to the start of dialysis and after 6 months of treatment with either hemodialysis (n=33) or peritoneal dialysis (n=13). RESULTS: After 6 months of treatment with hemodialysis there was an increase in total cholesterol (4.6+/-1.1 vs. 5.0+/-1.3 mmol/l; p<0.05) and triglycerides (2.0+/-0.9 vs. 2.8+/-1.6 mmol/l; p<0.03). In the peritoneal dialysis group the lipoproteins did not change. Regarding lipid peroxides and in vitro copper-induced LDL oxidation, also no changes were observed after 6 months of treatment in both groups. CONCLUSION: Dyslipidemia aggravates after 6 months of hemodialysis but not after 6 months of peritoneal dialysis. During this period, no net effects on oxidative stress were demonstrated.

Results of an international round robin for the quantification of serum non-transferrin-bound iron: Need for defining standardization and a clinically relevant isoform.

Non-transferrin-bound iron (NTBI) appears in the circulation of patients with iron overload. Various methods to measure NTBI were comparatively assessed as part of an international interlaboratory study. Six laboratories participated in the study, using methods based on iron mobilization and detection with iron chelators or on reactivity with bleomycin. Serum samples of 12 patients with hereditary (n=11) and secondary (n=1) hemochromatosis were measured during a 3-day analysis using 4 determinations per sample per day, making a total of 144 measurements per laboratory. Bland-Altman plots for repeated measurements are presented. The methods differed widely in mean serum NTBI level (range 0.12-4.32mumol/L), between-sample variation (SD range 0.20-2.13mumol/L and CV range 49.3-391.3%), and within-sample variation (SD range 0.02-0.45mumol/L and CV range 4.4-193.2%). The results obtained with methods based on chelators correlated significantly (R(2) range 0.86-0.99). On the other hand, NTBI values obtained by the various methods related differently from those of serum transferrin saturation (TS) when expressed in terms of both regression coefficients and NTBI levels at TS of 50%. Recent studies underscore the clinical relevance of NTBI in the management of iron-overloaded patients. However, before measurement of NTBI can be introduced into clinical practice, there is a need for more reproducible protocols as well as information on which method best represents the pathophysiological phenomenon and is most pertinent for diagnostic and therapeutic purposes.

Low plasma levels of oxidized low density lipoprotein in preeclampsia.

BACKGROUND: Markers of lipid peroxidation are commonly used to assess oxidative stress in preeclampsia. The aim of this study was to assess the concentration of oxidized low density lipoprotein (oxLDL), a novel marker for lipid peroxidation, and that of the thiobarbituric acid reactive substances (TBARS) in the pathogenesis of severe preeclampsia and to investigate the influence of gestational age on these parameters. METHOD: Plasma levels of oxLDL and TBARS were assayed in women with severe preeclampsia (n = 40), normotensive pregnant controls matched for gestational age (n = 24) and normotensive pregnant controls at full term (n = 16). RESULTS: Women with preeclampsia showed lower oxLDL levels (mean +/- SE) than matched controls (181 +/- 12 vs. 219 +/- 14; p = 0.027), whereas no differences were found for the TBARS concentration (3.8 +/- 0.6 vs. 3.7 +/- 0.4). When women with preeclampsia were compared to control women at full term, TBARS were elevated (3.8 +/- 0.6 vs. 1.5 +/- 0.2; p = 0.01). However, in women with normotensive pregnancy TBARS were also lower in full-term control pregnancy compared to early third-trimester values (p < 0.0001). CONCLUSION: Plasma TBARS decreased during the third trimester of pregnancy, underlining the importance of matching for gestational age when studying markers of lipid peroxidation in pregnant women. Women with preeclampsia had lower plasma levels of oxLDL compared to gestational age-matched controls, indicating that oxLDL could be a marker for preeclampsia.