Potential protective effect of nuclear factor-κB decoy oligodeoxynucleotides on endotoxin-induced liver injury

PURPOSE

We sought to study the protective effects of nuclear factor-κB decoy oligodeoxynucleotides (ODNs) on endotoxin-induced liver injury in a rat model.

METHODS

Sixty Sprague-Dawley rats were randomly divided into a control (n=20), a lipopolysaccharide (LPS) (n=20), and an NF-κB decoy ODN group (n=20). Liver and blood serum samples were collected at 24 hours after the operation. NF-κB binding activity was detected by an electrophoretic mobility shift assay, liver histopathology, by light microscopy; and cell apoptosis, by a terminal-deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling assay. The serum of liver enzyme (aspartate transaminase [AST]) levels were measured using an automated biochemical analyzer and tumor necrosis factor (TNF)-α and interleukin (IL)-6 by enzyme-linked immunosorbent assays.

RESULTS

NF-κB was dramatically activated after endotoxin-induced liver injury. Many hepatocytes underwent degeneration and necrosis in the LPS group. The expressions of AST, TNF-α, and IL-6 were significantly increased compared with the control group (P=.0005), However, NF-κB decoy ODNs altered these undesirable changes. On the other hand, IL-6 expression was not significantly decreased by the NF-κB decoy versus the LPS group (P=.0745).

CONCLUSIONS

NF-κB decoy strategy inhibited the binding activity of NF-κB, thus suppressing production of downstream cytokines which play crucial roles in protection from endotoxin-induced injury.

Liver X receptor activation attenuates inflammatory response and protects cholinergic neurons in APP/PS1 transgenic mice

Alzheimer's disease (AD) is associated with beta-amyloid deposition, glial activation, and increased levels of the cytokines, as well as cholinergic dysfunction. Liver X receptor (LXR) has been found to inhibit the expression of pro-inflammatory genes. However, the effects of LXR activation on inflammatory response and on cholinergic system in AD are not yet clear. The present results revealed that LXR activation markedly attenuated several inflammatory markers and decreased microglial activation and reactive astrocytes in amyloid precursor protein (APP)/PS1 transgenic mice. Additionally, LXR activation significantly increased the number of cholinergic neurons in the medial septal regions and the basal nucleus of Meynert (NBM), and attenuated cognitive impairment. Furthermore, we observed that LXR activation inhibited the production of COX-2 and iNOS from Aβ(25-35)-induced microglia. LXR activation and nuclear factor kappa B (NF-κB) inhibitor PDTC both attenuated Aβ(25-35) induction of NF-κB activation. These results suggest that LXR agonists suppress the production of pro-inflammatory molecules, at least in part, by modulating NF-κB-signaling pathway. Collectively, these studies suggest that LXR agonists may have therapeutic significance in AD.

Age-dependent alterations of HLA-DR expression and effect of lipopolysaccharide on cytokine secretion of peripheral blood mononuclear cells in the elderly population

HLA-DR, a major histocompatibility complex, MHC class II, is involved in several autoimmune conditions, disease susceptibility and disease resistance. Here, we investigate the impact of different age individuals on HLA-DR expression on peripheral blood mononuclear cells (PBMCs) induced by lipopolysaccharide (LPS). The results indicate that HLA-DR expression on PBMCs in the population aged above 70 years significantly increased as compared with that in the lower-age groups by flow cytometry analysis (B-D; r = 0.690, P = 0.000265). In addition, followed by LPS stimulation, the levels of cytokine TNF-α, IL-6 and IL-10 secretion by allogeneic T lymphocytes from different age groups (A-D) were significantly increased (P < 0.05). Notably, levels of TNF-α and IL-6 were significantly reduced in groups B, C and D as compared with group A (P < 0.05), whereas levels of IL-10 increased (P = 0.012). However, no significant difference in PBMC-secreted TNF-α, IL-6 and IL-10 levels was observed among groups A, B, C and D (P > 0.05) before LPS stimulation. We firstly present data showing an age-dependent increase in HLA-DR expression in the population aged above 70 years and the individual with aged above 70 years has reduced the secretion of inflammatory mediators (TNF-α and IL-6) by PBMCs and increased the secretion of anti-inflammatory cytokine (IL-10) after LPS stimulation in vitro. The better understanding of HLR-DR expression on human PBMCs in aged individuals and its relation to the host cellular immunity would provide important insights into the immunity of aged individuals and particularly, in elderly patients with sepsis.

Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease

Mechanisms associated with the progression of simple steatosis to non-alcoholic fatty liver disease (NAFLD) remain undefined. Regulatory T cells (T(regs)) play a critical role in regulating inflammatory processes in non-alcoholic steatohepatitis (NASH) and because T helper type 17 (Th17) functionally oppose T(reg)-mediated responses, this study focused on characterizing the role of Th17 cells using a NAFLD mouse model. C57BL/6 mice were fed either a normal diet (ND) or high fat (HF) diet for 8 weeks. Mice in the HF group had a significantly higher frequency of liver Th17 cells compared to ND-fed mice. Neutralization of interleukin (IL)-17 in HF mice ameliorated lipopolysaccharide (LPS)-induced liver injury reflected by decreased serum alanine aminotransferase (ALT) levels and reduced inflammatory cell infiltrates in the liver. In vitro, HepG2 cells cultured in the presence of free fatty acids (FFA; oleic acid and palmitic acid) for 24 h and IL-17 developed steatosis via insulin-signalling pathway interference. IL-17 and FFAs synergized to induce IL-6 production by HepG2 cells and murine primary hepatocytes which, in combination with transforming growth factor (TGF-β), expanded Th17 cells. It is likely that a similar process occurs in NASH patients, as there were significant levels of IL-17(+) cell infiltrates in NASH patient livers. The hepatic expression of Th17 cell-related genes [retinoid-related orphan receptor gamma (ROR)γt, IL-17, IL-21 and IL-23] was also increased significantly in NASH patients compared to healthy controls. Th17 cells and IL-17 were associated with hepatic steatosis and proinflammatory response in NAFLD and facilitated the transition from simple steatosis to steatohepatitis. Strategies designed to alter the balance between Th17 cells and T(regs) should be explored as a means of preventing progression to NASH and advanced liver diseases in NAFLD patients.

Expression of the stem cell marker nestin in pre/hypertrophic chondrocytes in osteochondroma

The pathogenesis of osteochondroma, the most common benign bone tumour, is not fully known. To date, regulation of nestin protein levels in osteochondromas and normal growth plates has not been reported. This study used immunohistochemical analysis to detect nestin protein levels in 48 osteochondromas and 13 normal growth plates (eight fetal and five postnatal). Nestin protein was mainly restricted to prehypertrophic and hypertrophic chondrocytes in osteochondroma. Nestin levels were significantly higher in osteochondromas in adolescents (age range 4 - 18 years, n = 32) than in osteochondromas in young adults (age range 20 - 28 years, n = 11), and significantly higher in osteochondromas in young adults than in those in older adults (age range 40 - 77 years; n = 5). Nestin protein was not present in normal growth plates. The presence of nestin protein parallels the biological behaviour of osteochondromas and is restricted to prehypertrophic and hypertrophic chondrocytes, indicating that these nestin-positive cells may be central to osteochondroma development.

Pharmacogenetics of the mycophenolic acid targets inosine monophosphate dehydrogenases IMPDH1 and IMPDH2: gene sequence variation and functional genomics

BACKGROUND AND PURPOSE

Inosine monophosphate dehydrogenases, encoded by IMPDH1 and IMPDH2, are targets for the important immunosuppressive drug, mycophenolic acid (MPA). Variation in MPA response may result, in part, from genetic variation in IMPDH1 and IMPDH2.

EXPERIMENTAL APPROACH

We resequenced IMPDH1 and IMPDH2 using DNA from 288 individuals from three ethnic groups and performed functional genomic studies of the sequence variants observed.

KEY RESULTS

We identified 73 single nucleotide polymorphisms (SNPs) in IMPDH1, 59 novel, and 25 SNPs, 24 novel, in IMPDH2. One novel IMPDH1 allozyme (Leu275) had 10.2% of the wild-type activity as a result of accelerated protein degradation. Decreased activity of the previously reported IMPDH2 Phe263 allozyme was primarily due to decreased protein quantity, also with accelerated degradation. These observations with regard to the functional implications of variant allozymes were supported by the IMPDH1 and IMPDH2 X-ray crystal structures. A novel IMPDH2 intron 1 SNP, G > C IVS1(93), was associated with decreased mRNA quantity, possibly because of altered transcription.

CONCLUSIONS AND IMPLICATIONS

These results provide insight into the nature and extent of sequence variation in the IMPDH1 and IMPDH2 genes. They also describe the influence of gene sequence variation that alters the encoded amino acids on IMPDH function and provide a foundation for future translational studies designed to correlate sequence variation in these genes with outcomes in patients treated with MPA.