Lactate Dehydrogenase-Elevating Virus Infection Inhibits MOG Peptide Presentation by CD11b+CD11c+ Dendritic Cells in a Mouse Model of Multiple Sclerosis.

Infections may affect the course of autoimmune inflammatory diseases of the central nervous system (CNS), such as multiple sclerosis (MS). Infections with lactate dehydrogenase-elevating virus (LDV) protected mice from developing experimental autoimmune encephalomyelitis (EAE), a mouse counterpart of MS. Uninfected C57BL/6 mice immunized with the myelin oligodendrocyte glycoprotein peptide (MOG35-55) experienced paralysis and lost weight at a greater rate than mice who had previously been infected with LDV. LDV infection decreased the presentation of the MOG peptide by CD11b+CD11c+ dendritic cells (DC) to pathogenic T lymphocytes. When comparing non-infected mice to infected mice, the histopathological examination of the CNS showed more areas of demyelination and CD45+ and CD3+, but not Iba1+ cell infiltration. These results suggest that the protective effect of LDV infection against EAE development is mediated by a suppression of myelin antigen presentation by a specific DC subset to autoreactive T lymphocytes. Such a mechanism might contribute to the general suppressive effect of infections on autoimmune diseases known as the hygiene hypothesis.

Enhanced Mouse Susceptibility to Endotoxin Shock after Plasmodium yoelii Infection Is Correlated with Increased Serum Levels of Lipopolysaccharide Soluble Receptors.

Sepsis is a common disease in sub-Saharan Africa and Asia, where malaria is also prevalent. To determine whether Plasmodium infection might enhance susceptibility to endotoxin shock, we used a mouse model of lipopolysaccharide (LPS) administration. Our results indicated that Plasmodium yoelii infection in mice strongly enhanced the susceptibility of the host to develop endotoxin shock. This increased susceptibility to endotoxin shock was correlated with a synergistic effect of Plasmodium and LPS on the secretion of Tumor Necrosis Factor (TNF). TNF contributed mostly to lethality after the dual challenge since neutralization with an anti-TNF antibody provided protection from death. Plasmodium infection also induced an enhancement of the serum levels of LPS soluble ligands, sCD14 and Lipopolysaccharide Binding Protein. In this regard, our data confirm that Plasmodium infection can profoundly modify responses to secondary bacteria challenges, resulting in dysregulated cytokine expression and pathological effects. If confirmed in humans, LPS soluble receptors might serve as markers of susceptibility to septic shock.

Inhibition of IL-12 heterodimers impairs TLR9-mediated prevention of early mouse plasmacytoma cell growth.

Introduction: Natural prevention of cancer development depends on an efficient immunosurveillance that may be modulated by environmental factors, including infections. Innate lymphoid cytotoxic cells have been shown to play a major role in this immunosurveillance. Interleukin-12 (IL-12) has been suggested to be a key factor in the activation of innate cytotoxic cells after infection, leading to the enhancement of cancer immunosurveillance. Methods: The aim of this work was to analyze in mouse experimental models by which mechanisms the interaction between infectious agent molecules and the early innate responses could enhance early inhibition of cancer growth and especially to assess the role of IL-12 by using novel antibodies specific for IL-12 heterodimers. Results: Ligation of toll-like receptor (TLR)9 by CpG-protected mice against plasmacytoma TEPC.1033.C2 cell early growth. This protection mediated by innate cytolytic cells was strictly dependent on IL-12 and partly on gamma-interferon. Moreover, the protective effect of CpG stimulation, and to a lesser extent of TLR3 and TLR7/8, and the role of IL-12 in this protection were confirmed in a model of early mesothelioma AB1 cell growth. Discussion: These results suggest that modulation of the mouse immune microenvironment by ligation of innate receptors deeply modifies the efficiency of cancer immunosurveillance through the secretion of IL-12, which may at least partly explain the inhibitory effect of previous infections on the prevalence of some cancers.

Lactate dehydrogenase-elevating virus enhances natural killer cell-mediated immunosurveillance of mouse mesothelioma development.

BACKGROUND: Viral infections can reduce early cancer development through enhancement of cancer immunosurveillance. This study was performed to analyse this effect of viral infection in a mouse model of solid tumor. METHODS: The experimental model used was the effect of BALB/c mouse infection by lactate dehydrogenase-elevating virus on AB1 mesothelioma cancer development. RESULTS: Acute infection with lactate dehydrogenase-elevating virus strongly reduced in vivo early AB1 mesothelioma growth and death resulting from cancer development. This effect was not due to a direct cytolytic effect of the virus on AB1 cells, but to an in vivo activation of natural killer cells. Gamma-interferon production rather than cytotoxic activity against AB1 cells mediated this protective effect. This gamma-interferon production by natural killer cells was dependent on interleukin-12 production. CONCLUSIONS: Together with other reported effects of infectious agents on cancer development, this observation may support the hypothesis that enhancement of innate immunosurveillance against tumors may result from infection with common infectious agents through modulation of the host immune microenvironment.

Lipid profiles and determinants of total cholesterol and hypercholesterolaemia among 25-74 year-old urban and rural citizens of the Yangon Region, Myanmar: a cross-sectional study.

OBJECTIVE: The first is to estimate the prevalence of dyslipidaemia (hypercholesterolaemia, hypertriglyceridaemia, high low-density lipoprotein (LDL) level and low high-density lipoprotein (HDL) level), as well as the mean levels of total cholesterol, triglyceride, LDL and HDL, in the urban and rural Yangon Region, Myanmar. The second is to investigate the association between urban-rural location and total cholesterol. DESIGN: Two cross-sectional studies using the WHO STEPS methodology. SETTING: Both the urban and rural areas of the Yangon Region, Myanmar. PARTICIPANTS: A total of 1370 men and women aged 25-74 years participated based on a multistage cluster sampling. Physically and mentally ill people, monks, nuns, soldiers and institutionalised people were excluded. RESULTS: Compared with rural counterparts, urban dwellers had a significantly higher age-standardised prevalence of hypercholesterolaemia (50.7% vs 41.6%; p=0.042) and a low HDL level (60.6% vs 44.4%; p=0.001). No urban-rural differences were found in the prevalence of hypertriglyceridaemia and high LDL. Men had a higher age-standardised prevalence of hypertriglyceridaemia than women (25.1% vs 14.8%; p<0.001), while the opposite pattern was found in the prevalence of a high LDL (11.3% vs 16.3%; p=0.018) and low HDL level (35.3% vs 70.1%; p<0.001).Compared with rural inhabitants, urban dwellers had higher age-standardised mean levels of total cholesterol (5.31 mmol/L, SE: 0.044 vs 5.05 mmol/L, 0.068; p=0.009), triglyceride (1.65 mmol/L, 0.049 vs 1.38 mmol/L, 0.078; p=0.017), LDL (3.44 mmol/L, 0.019 vs 3.16 mmol/L, 0.058; p=0.001) and lower age-standardised mean levels of HDL (1.11 mmol/L, 0.010 vs 1.25 mmol/L, 0.012; p<0.001). In linear regression, the total cholesterol was significantly associated with an urban location among men, but not among women. CONCLUSION: The mean level of total cholesterol and the prevalence of hypercholesterolaemia were alarmingly high in men and women in both the urban and rural areas of Yangon Region, Myanmar. Preventive measures to reduce cholesterol levels in the population are therefore needed.