Search

Accumulating researches reported that particulate matter (PM2.5) is a risk factor for developing various diseases, including metabolic syndrome. Recently, inactive rhomboid protein 2 (iRhom2) was considered as a necessary modulator for shedding of tumor necrosis factor-α (TNF-α) in immune cells. TNF-α, a major pro-inflammatory cytokine, was linked to various pathogenesis of diseases, including dyslipidemia. Here, wild type (WT) and iRhom2-knockout (iRhom2 −/− ) mice were used to investigate the effects of iRhom2 on PM2.5-induced hepatic dyslipidemia. The hepatic histology, inflammatory response, glucose tolerance, serum parameters and gene expressions were analyzed. We found that long-term inhalation of PM2.5 resulted in hepatic steatosis. And a significant up-regulation of iRhom2 in liver tissues was observed, accompanied with elevated TNF-α, TNF-α converting enzyme (TACE), TNFα receptor (TNFR)2 and various inflammatory cytokines expressions. Additionally, PM2.5 treatment caused TG and TC accumulation in serum and liver, probably attributed to changes of genes modulating lipid metabolism. Intriguingly, hepatic injury and dyslipidemia were attenuated by iRhom2 −/− in mice with PM2.5 challenge. In vitro, iRhom2-knockdwon reduced TNF-α expressions and its associated inflammatory cytokines in Kupffer cells, implying that liver-resident macrophages played an important role in regulating hepatic inflammation and lipid metabolism in cells treated with PM2.5. The findings indicated that long-term PM2.5 exposure caused hepatic steatosis and dyslipidemia through triggering inflammation, which was, at least partly, dependent on iRhom2/TNF-α pathway in liver-resident macrophages. [ABSTRACT FROM AUTHOR]

Type 1 diabetes (T1D) is a metabolic disease induced by abnormal insulin secretions from damaged islet B cells. Clinical observations have shown that T1D patients are more easily infected by influenza A virus (IAV) and suffer more serious symptoms than non-T1D patients. To investigate the susceptibility of T1D mice to IAV, a T1D mouse model was built by intraperitoneal injection of diluted streptozotocin (STZ) over 5 consecutive days, followed by infection with three subtypes of IAV (H1N1/H5N1/H7N2). The T1D-infected mice showed more serious clinical symptoms and lower survival rates than the non-T1D infected mice. The hematoxylin and eosin (H&E) staining results revealed an increase in serious pathological damage to the lung and pancreas in T1D-infected mice. Immunohistochemistry results indicated higher IAV loads and a more extensive distribution of positive signals in the lungs and pancreas of T1D-infected mice than in those of non-T1D infected mice. Furthermore, according to real-time quantitative polymerase chain reaction (PCR) results, viral replication appeared to occur more easily in the lungs of T1D-infected mice. Thus, T1D-infected mice exhibited higher susceptibility to IAV than did normal mice. This study contributes a mouse model suitable for T1D research as well as valuable information about the mechanism underlying T1D patients' increased susceptibility to IAV. [ABSTRACT FROM AUTHOR]

Nodamura virus (NoV) lethally infects suckling mice and contains a segmented positive-strand RNA genome that encodes a potent suppressor of RNA interference (RNAi). Recent studies have demonstrated immune detection and subsequent processing of NoV dsRNA replicative intermediates by the mouse RNAi machinery. However, diverse RNA viruses, including Encephalomyocarditis virus that also triggers Dicer-dependent biogenesis of viral siRNAs in mouse cells, are targeted in mammals by RIG-I-like receptors that initiate an IFN-dependent antiviral response. Using mouse embryonic fibroblasts (MEFs) for NoV infection, here we show that MEFs derived from mice knockout for RIG-I, but not those knockout for MDA5, LGP2, TLR3 or TLR7, exhibited an enhanced susceptibility to NoV. Further studies indicate that NoV infection induced an IFN-dependent antiviral response mediated by RIG-I. Our findings suggest that RIG-I directs a typical IFN-dependent antiviral response against an RNA virus capable of suppressing the RNAi response. [ABSTRACT FROM AUTHOR]

Chronic high-frequency repetitive transcranial magnetic stimulation (rTMS) is a noninvasive method to increase the excitability of neurons, and it induces long-term effects that can improve symptoms related to neurodegenerative diseases, including cognitive ability. The present study was undertaken to identify the mechanism by which rTMS improves cognitive impairments in mice. The novel object recognition test in vivo was used to evaluate the cognitive function of the mice. Whole-cell patch-clamp recordings were used to evaluate the neuronal excitability, including the resting membrane potential, the number of action potentials induced by depolarized current, after-hyperpolarization, and the voltage-dependent Ca 2+ current in hippocampal slices. We found that the aged mice showed impairments in cognitive function, and high-frequency (25 Hz) rTMS for 14 consecutive-days ameliorated the impairments. Whole-cell patch-clamp recordings showed that, compared to matured mice, the hippocampal CA1 pyramidal neurons of aged mice showed significantly hyperpolarized resting membrane potential, significantly decreased numbers of action potentials after injection of depolarizing current, and significantly increased after-hyperpolarization after an action potential. The exposure to high-frequency rTMS significantly improved the above deficits in the neuronal excitability in the aged rTMS mice. Consistent with the above changes, the exposure to high-frequency rTMS also significantly decreased the voltage-dependent Ca 2+ current of the neurons compared with the aged sham mice. These data suggested that the rTMS could improve the age-related cognitive impairment in parallel with regulating the neuronal excitability and modifying the voltage-dependent Ca 2+ channels. [ABSTRACT FROM AUTHOR]

Abstract: Streptococcus suis is an important swine pathogen responsible for a diverse range of diseases. S. suis serotype 2 (SS2) and S. suis serotype 9 (SS9) are the prevalent serotypes in diseased Chinese pigs. Little is known about SS9 virulence factors. Two strains, GZ0565 and SH040917, were isolated from a diseased pig and a healthy pig, respectively. Suppression subtractive hybridization (SSH) was used to identify SS9 virulence genes associated with pathogenicity. We identified 30 gene fragments unique to GZ0565, including stp which encodes a serine/threonine protein phosphatase known to affect the virulence and morphology of bacteria. To investigate the role of stp in pathogenesis of SS9, an isogenic stp mutant (Δstp) and a complementation strain (CΔstp) were constructed. The results demonstrated that the stp affected the expression of a few genes involving in adhesion and virulence for bacteria. The Δstp exhibited a significant decrease in HEp-2 cell adherence, compared with the wild type, and a reduced survival ratio in whole blood. The Δstp was attenuated in a CD1 murine model of infection and its LD50 values was seven-fold higher than the wild type. Our data suggest that stp is involved in the pathogenesis of SS9. [Copyright &y& Elsevier]