Successful interferon therapy reverses enhanced hepatic iron accumulation and lipid peroxidation in chronic hepatitis C

OBJECTIVES: Hepatic iron deposition has been reported in chronic hepatitis C (CH-C), and iron-induced lipid peroxidation may be involved in the pathogenesis of CH-C. The aims of the present study were: 1) to determine whether patients with CH-C have evidence of enhanced hepatic lipid peroxidation and to evaluate its relation to iron status, compared with that in patients with chronic hepatitis B (CH-B); and 2) to assess the effect of interferon (IFN) therapy on hepatic iron and lipid peroxidation. METHODS: In the liver biopsies of 40 patients with CH-C and 26 patients with CH-B, immunohistochemical detection of 4-hydroxy-2-nonenal (HNE)-protein adducts for evaluation of lipid peroxidation was performed, and hepatic iron status was biochemically and histologically assessed. In 16 CH-C patients with normal serum transaminases and undetectable serum HCV-RNA >6 months after the end of IFN treatment (responders) and in 11 nonresponders, hepatic HNE-protein adducts and siderosis were evaluated in pre- and posttreatment liver biopsies. RESULTS: Hepatocytic HNE-protein adducts and iron deposits were more abundant in the patients with CH-C than in those with CH-B. No correlation was found between the levels of hepatocytic HNE-protein adducts and hepatic iron status in either of the two groups. In the responders to IFN treatment for CH-C, hepatocytic HNE-protein adducts disappeared or attenuated with improvement of hepatic siderosis after the treatment, whereas IFN treatment did not improve hepatocytic expression of HNE-protein adducts and hepatic siderosis in the nonresponders. CONCLUSIONS: Patients with CH-C have evidence of enhanced hepatic iron accumulation and lipid peroxidation compared to those with CH-B. In CH-C, hepatic siderosis and lipid peroxidation are improved with successful IFN treatment. These results suggest that hepatic lipid peroxidation and iron may potentially play contributory roles in the pathogenesis of CH-C.     

Haptoglobin genotype, anaemia and malaria in Gambian children

Objective  To retest our previous finding that the haptoglobin (Hp) 22 genotype is associated with seasonal anaemia, and to investigate the role of malaria in this effect.
Methods  Haemoglobin (Hb) and peripheral parasitaemia were assessed at pre- and post-malarial season cross-sectional surveys in rural Gambian children aged 10–72 months. Between the surveys, active longitudinal surveillance was conducted to detect febrile episodes.
Results  Unlike previously, no overall reduction in Hb was observed (Hb = 106.1 vs. 107.2 g/l, P  = 0.13, n  = 545). However, multi-variable linear regression revealed differences in Hb over the season by Hp and Hb-sickle (HbS) genotype (−2.20 g/l per copy of the Hp2 allele, P  = 0.043; HbAS vs. HbAA + 3.13 g/l, P  = 0.11, n  = 536). There was no effect of malarial episodes during follow-up; this suggests that when effective treatment is given, Hb levels recover. The A61-C Hp promoter SNP, associated with the Hp2 allele, had no effect.
Conclusion  The effect of the Hp2 allele appears to be independent of effects on malaria incidence but may affect Hb levels through increased oxidant stress and red cell turnover. This may be supported by our previous observations that the effect of Hp22 was independent of markers of iron status and zinc protoporphyrin measured at the cross-sectional surveys and therefore also of iron availability for erythropoiesis.     

分拣受体Sortilin促进巨噬细胞内脂质蓄积

目的探讨分拣受体Sortilin对THP-1巨噬细胞内脂质代谢的影响。方法用氧化型低密度脂蛋白(ox-LDL)孵育THP-1巨噬细胞。Western blot检测荷脂后THP-1巨噬细胞中Sortilin表达变化;THP-1巨噬细胞Sortilin高表达和沉默后,液体闪烁计数仪检测胞内胆固醇流出,高效液相色谱法检测细胞内脂质含量,油红O染色观察胞内脂滴情况。结果 THP-1巨噬细胞Sortilin表达呈ox-LDL剂量和时间依赖性增加;以50 mg/L ox-LDL处理24 h后THP-1巨噬细胞Sortilin表达水平达到高峰。与对照组相比,Sortilin过表达后巨噬细胞胆固醇流出减少,胞内脂质含量增加且脂滴明显增多,而Sortilin沉默后则刚好出现相反的结果。结论 Sortilin抑制巨噬细胞内胆固醇流出,促进胞内脂质蓄积。     

Foam cells of the rabbit atherosclerotic plaque arrested in metaphase by colchicine show a macrophage phenotype

Proliferative activity of smooth muscle cells and foam cells characterizes experimental atherosclerotic plaques as they first appear. Immunohistochemical and ultrastructural methods were applied to cells arrested in metaphase by colchicine and the phenotype of cells in mitosis was detected. Most of the metaphase arrested FC found in aortic plaques of cholesterol fed New Zealand rabbits were positive to the anti-macrophage monoclonal antibody and negative to the anti-smooth muscle actin monoclonal antibody. Moreover, most of the metaphase blocked FC had the ultrastructural features of macrophages. These preliminary results further strengthen previous observations on rabbit plaques that the FC pool is mainly constituted by macrophages and show, for the first time, that the dimension of this pool depends not only on migration of circulating monocytes but also on the in situ proliferation of macrophages.     

Haptoglobin genotype is a regulator of reverse cholesterol transport in diabetes in vitro and in vivo

Two common alleles exist at the haptoglobin (Hp) locus, and the Hp2 allele is associated with an increased incidence of cardiovascular disease, specifically in diabetes mellitus (DM). Oxidative stress is increased in Hp2 mice and humans with DM. Oxidative modification of the apolipoprotein A-I inhibits reverse cholesterol transport. We sought to test the hypothesis that reverse cholesterol transport is impaired in Hp2 DM mice and humans. In vitro, using serum from non-DM and DM individuals, we measured cholesterol efflux from (3)H-cholesterol-labeled macrophages. In vivo, we injected (3)H-cholesterol-loaded macrophages intraperitoneally into non-DM and DM mice with the Hp1-1 or Hp2-2 genotype and monitored (3)H-tracer levels in plasma, liver, and feces. In vitro, in DM individuals only, we observed significantly decreased cholesterol efflux from macrophages incubated with serum from Hp2-1 or Hp2-2 as compared with Hp1-1 individuals (P<0.01). The interaction between Hp type and DM was recapitulated using purified Hp and glycated Hb. In vivo, DM mice loaded with (3)H-cholesterol-labeled macrophages had a 40% reduction in (3)H-cholesterol in plasma, liver, and feces as compared with non-DM mice (P<0.01). The reduction in reverse cholesterol transport associated with DM was significantly greater in Hp2-2 mice as compared with Hp1-1 mice (54% versus 25% in plasma; 52% versus 27% in liver; 57% versus 32% in feces; P<0.03). reverse cholesterol transport is decreased in Hp2-2 DM. This may explain in part the increased atherosclerotic burden found in Hp2-2 DM individuals.     

Haptoglobin type neither influences iron accumulation in normal subjects nor predicts clinical presentation in HFE C282Y haemochromatosis: phenotype and genotype analysis

In the UK, 90% of patients with hereditary haemochromatosis (HH) are homozygous for HFE C282Y, as are one in 150 people in the general population. However, only a minority of these will develop clinical haemochromatosis. Iron loss modifies iron accumulation but so may other genetic factors. Haptoglobin (Hp) exists as three major types (Hp 1-1, Hp 2-1 or Hp 2-2) and binds free plasma haemoglobin. In men, Hp 2-2 has been shown to be associated with increased macrophage iron accumulation and serum ferritin concentration. Furthermore, the frequency of Hp 2-2 was shown to be increased in patients with HH. We determined Hp types by phenotyping and genotyping 265 blood donor control subjects and 173 subjects who were homozygous for HFE C282Y. The latter group included 66 blood donors lacking clinical features suggestive of haemochromatosis and without a known family history, and 68 patients presenting clinically with haemochromatosis. Hp 2-2 frequencies did not differ in control subjects and C282Y homozygotes. Hp 2-2 was not a risk factor for disease development in HH. To investigate the relationship between iron accumulation and haptoglobin type, we determined transferrin saturation and serum ferritin concentration in 192 male, first-time blood donors aged 20-40 years who lacked both HFE C282Y and H63D. Transferrin saturation and serum ferritin concentrations did not vary with Hp type.     

Modulation of age-related alterations of iron,ferritin, and lipid peroxidation in rat serum

It is generally accepted that oxidative stress increases with age, as indicated by age-related increases in lipid peroxidation. Also found in the aged organism is the accumulation of iron in various tissues. The increase in lipid peroxidation and tissue iron accumulation may not have been coincidental, but rather may be a causally related phenomenon, since iron involvement in lipid peroxidation is a well-accepted phenomenon in free radical metabolism. Our present study examined serum iron and ferritin as means to compare age-related changes in lipid peroxides and peroxidizability in aged rats. In addition, the anti-aging effect of dietary restriction on the modulation of iron status and lipid peroxidation was assessed. The results showed that the age-related increase in serum iron concurs with increased lipid peroxidation, and that these adverse changes were effectively attenuated by dietary restriction. Our finding is the first report on the modulation of iron status by long-term calorie restriction, and is consistent with the previous findings on the anti-peroxidative action of dietary restriction.     

Red cell lipid peroxidation and antioxidant enzymes in iron deficiency

Whether iron deficient RBC in humans have a reduced, or an increased, susceptibility to lipid peroxidation was studied in the iron deficiency states of primary proliferative polycythaemia and iron deficiency anaemia and related to changes in the activities of iron-dependent and non-iron dependent antioxidant enzymes. Susceptibility of RBCs to lipid peroxidation was increased when expressed per g Hb. However, this was a result of the low RBC Hb giving an increased membrane lipid: Hb ratio in the incubations. Results were normal when expressed either per cell, or per ml, RBC. Glutathione reductase was normal. Increased RBC superoxide dismutase activity in iron deficiency may be explained by the younger RBC population and reductions in glutathione peroxidase and catalase activities by the microcytic hypochromic changes and the lack of availability of iron, respectively. There is no evidence of an increased susceptibility of RBC to lipid peroxidation in iron deficiency.     

Inhibition of plaque neovascularization reduces macrophage accumulation and progression of advanced atherosclerosis

Plaque angiogenesis promotes the growth of atheromas, but the functions of plaque capillaries are not fully determined. Neovascularization may act as a conduit for the entry of leukocytes into sites of chronic inflammation. We observe vasa vasorum density correlates highly with the extent of inflammatory cells, not the size of atheromas in apolipoprotein E-deficient mice. We show atherosclerotic aortas contain activities that promote angiogenesis. The angiogenesis inhibitor angiostatin reduces plaque angiogenesis and inhibits atherosclerosis. Macrophages in the plaque and around vasa vasorum are reduced, but we detect no direct effect of angiostatin on monocytes. After angiogenesis blockade in vivo, the angiogenic potential of atherosclerotic tissue is suppressed. Activated macrophages stimulate angiogenesis that can further recruit inflammatory cells and more angiogenesis. Our findings demonstrate that late-stage inhibition of angiogenesis can interrupt this positive feedback cycle. Inhibition of plaque angiogenesis and the secondary reduction of macrophages may have beneficial effects on plaque stability.     

Nitric oxide is a key determinant of group B streptococcus-induced murine macrophage apoptosis

Group B streptococcus (GBS; Streptococcus agalactiae) induces apoptosis of macrophages, and this may be an important mechanism GBS uses to suppress immune responses. The mechanisms whereby GBS induces apoptosis have not been identified. We studied GBS infection in murine macrophage-like J774A.1 cells and analyzed gene expression before apoptosis. Tumor necrosis factor (TNF)-alpha , interleukin (IL)-1, and inducible nitric oxide synthase (iNOS) gene expression coincided with apoptosis. Inhibition of iNOS gene expression by use of N(G)-monomethyl-L-arginine (NMMA) inhibited apoptosis, whereas inhibition of TNF-alpha and IL-1 biological activity did not. Macrophages from congenic iNOS-deficient mice were less susceptible to apoptosis than were macrophages from C57BL/6 mice. The NO donor S-nitroso-N-acetylpenicillamine (SNAP) induced apoptosis without infection, confirming its proapoptotic effect. NMMA did not impair the microbicidal activity of macrophages, however, and SNAP was not bactericidal against GBS in vitro. In human monocyte-derived macrophages (HMDMs), NO production was minimal, even after costimulation with IFN-gamma and lipopolysaccharide. Dose-dependent apoptosis of HMDMs occurred without a significant NO response. Thus, NO is an important mediator of GBS-induced murine macrophage apoptosis but does not contribute to antimicrobial activity or cytotoxicity in HMDMs. HMDMs and murine macrophages are killed by GBS by alternative, NO-independent mechanisms. Future studies of host-cell machinery commandeered by GBS to bring about apoptosis will be important for understanding the role played by apoptosis in defense against this important human pathogen.     

ED-B fibronectin (ED-B) can be targeted using a novel single chain antibody conjugate and is associated with macrophage accumulation in atherosclerotic lesions

It has been shown that ED-B fibronectin (ED-B) is a potential target for plaque imaging. The aim of this study was to test a novel modified single chain anti-ED-B antibody (scFv) conjugated for near infrared fluorescence imaging (NIRF) with tetrasulfonated carbocyanine-maleimide (TSC-scFv) and to examine the association of ED-B with the presence of macrophages in a murine model of atherosclerosis. Expression of ED-B was observed in plaque areas in apolipoprotein E–deficient (apoE^–/–) mice which increased with age and plaque load. Robust imaging was possible after explantation of the aorta and demonstrated a strong NIRF signal intensity in focal aortic and brachiocephalic plaque lesions, whereas no signals were found in undiseased areas. Plaque lesion ED-B was expressed by smooth muscle cell and was closely associated to macrophage infiltrates. Although not expressed by the same cell type, there was a significant correlation (p<0.01) between ED-B and macrophage immunoreactivity. In vitro human coronary and mouse smooth muscle cells significantly increased ED-B expression after angiotensin II and TNF-α treatment.This study demonstrates that plaque NIRF imaging is feasible with a novel single chain antibody and that ED-B expression is closely associated with inflammation in experimental atherosclerosis. *both authors contributed equally to this work