Limited expression of TLR9 on T cells and its functional consequences in patients with nonalcoholic fatty liver disease.

BACKGROUND/AIMS: Toll-like receptors (TLRs) modulate T cell responses in diverse diseases. Co-stimulation of T cell activation via TLR9 induces production of interferon gamma (IFN-γ), priming of which is critical for differentiation of pro-inflammatory macrophages. These macrophages have a crucial role in nonalcoholic fatty liver disease (NAFLD). We aimed to evaluate the expression of TLR9 protein on T cells and the consequences of TLR9-mediated triggering of these cells in patients with NAFLD. METHODS: Our study included 34 patients with simple steatosis, 34 patients with nonalcoholic steatohepatitis, eight patients with NAFLD who met general diagnostic criteria but lacked histological diagnosis, and 51 control subjects. We used a synthetic TLR9 ligand to co-stimulate T cells. We measured TLR9 expression in liver and peripheral T cells and CD69 and IFN-γ as phenotypic markers of T cell activation and differentiation by flow cytometry. RESULTS: TLR9 expression on liver and peripheral T cells was lowest in patients with simple steatosis and was positively associated with anthropometric, biochemical, and histopathological features of NAFLD. In vitro co-stimulation of T cells from patients with simple steatosis induced a limited number of IFN-γ-producing CD8+ T cells. At baseline, these patients showed a low frequency of circulating type 1 CD8+ cells. CONCLUSION: The positive associations between TLR9 and anthropometric, clinical, and histological features and the crucial role of IFN-γ-in NAFLD suggest that limited TLR9 expression and production of IFN-γ play a protective role in patients with simple steatosis.

New evidence for the therapeutic potential of curcumin to treat nonalcoholic fatty liver disease in humans.

INTRODUCTION: The immune system acts on different metabolic tissues that are implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Leptin and linoleic acid have the ability to potentially affect immune cells, whereas curcumin is a known natural polyphenol with antioxidant and anti-inflammatory properties. AIMS: This study was designed to evaluate the pro-inflammatory and pro-oxidant effects of leptin and linoleic acid on immune cells from patients with NAFLD and to corroborate the modulatory effects of curcumin and its preventive properties against the progression of NAFLD using a high-fat diet (HFD)-induced NAFLD/nonalcoholic steatohepatitis mouse model. RESULTS: The ex vivo experiments showed that linoleic acid increased the production of reactive oxygen species in monocytes and liver macrophages, whereas leptin enhanced tumor necrosis factor-α (TNF-α) production in monocytes and interferon-γ production in circulating CD4+ cells. Conversely, oral administration of curcumin prevented HFD-induced liver injury, metabolic alterations, intrahepatic CD4+ cell accumulation and the linoleic acid- and leptin- induced pro-inflammatory and pro-oxidant effects on mouse liver macrophages. CONCLUSION: Our findings provide new evidence for the therapeutic potential of curcumin to treat human NAFLD. However, the development of a preventive treatment targeting human circulating monocytes and liver macrophages as well as peripheral and hepatic CD4+ cells requires additional research.

Altered phenotype and functionality of circulating immune cells characterize adult patients with nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) is a chronic inflammatory liver disease associated with insulin resistance and its metabolic consequences. Leukocyte mobilization, intrahepatic activation, and an exacerbated production of reactive oxygen species (ROS) and cytokines contribute to the development of NASH. Though alterations in peripheral blood (PB) T cell proportions and functionality remain unidentified, they might play a main role in NASH progression. We have compared the phenotype and Th1/Th2 commitment of peripheral immune cell reservoirs in adult patients and controls as well as the ability of neutrophils and monocytes to handle an ex vivo challenge. Also, we correlated those parameters with the main histological characteristics in NASH. Compared with controls, patients showed increased numbers of CD4(+) cells and both CD4(+) and CD8(+) CD45RO subsets together with a higher frequency of IFN-γ-producing CD4(+) and CD8(+) T cells. We also found a decreased number of CD4(+) and CD8(+) CD45RA subsets. The distinctive production of IFN-γ highlights the significance of the observed skewed frequencies of PB T cells. Whereas ROS production by monocytes from NASH patients did not differ from controls, circulating neutrophils displayed a particularly higher phorbol myristate acetate-induced production of ROS. A negative correlation between oxidative burst and fibrosis grade was observed. This study reveals the presence of a characteristic profile of peripheral immune cells in NASH. We also discuss the probable influence of obesity on some of our present findings.

The simultaneous presence of IL-1B and TNFA two-positions risk haplotypes enhances the susceptibility for celiac disease.

To assess the joint contribution of interleukin 1 beta (IL-1B) and tumor necrosis factor alpha (TNFalpha) to the genetic risk of developing celiac disease (CD), we analyzed four biallelic polymorphisms of TNFA and IL-1B genes in 228 patients and 244 healthy controls. The individual contribution of TNFA -308A and IL-1B -511C alleles was weak (OR 1.47 and 1.66, respectively) and was null for TNFA -238 A/G and IL-1B +3953 C/T single nucleotide polymorphisms (SNPs). Due to the potential linkage disequilibrium between TNFA, human leukocyte antigen (HLA) -DQA1 and HLA-DQB1 genes, only individuals carrying DQ2 antigen (DQ2-positive) were considered to perform haplotype analyses. Two-position risk haplotypes were first defined by the combined presence of -511C and +3953T alleles for IL-1B (OR 9.402) or -308A and -238A alleles for TNFA (OR 15.389). The TNFA/IL-1B combined haplotype-stratified association analysis showed that the simultaneous presence of TNFA risk and IL-1B non-risk haplotypes (OR 13.32) but not TNFA non-risk and IL-1B risk haplotypes (OR 0.71) is associated with CD. Interestingly, our data suggest that the coexistence of both risk haplotypes seems to work synergistically (OR 29.59), which enhances the risk of developing CD.

Simultaneous expression of Th1 cytokines and IL-4 confers severe characteristics to type I autoimmune hepatitis in children.

To investigate the immunopathogenic mechanisms of type I autoimmune hepatitis in children, we analyzed by quantitative or semiquantitative reverse transcription-polymerase chain reaction the expression of cytokines interferon (IFN)-gamma, interleukin (IL)-12p40, IL-18, IL-4, IL-10, and IL-12R beta 2. In addition, liver and peripheral blood was collected to investigate the expression of the natural killer T (NKT) cell marker V alpha 24. The presence of NKT cells in hepatic lesions were also identified by immunohistochemistry. The analysis was performed on liver biopsies from 25 children with type I autoimmune hepatitis. As disease controls, we included six children with hepatitis C virus-related chronic hepatitis and nine control livers. The expression of IFN-gamma and IL-12p40 was not detected in controls but was clearly upregulated in pathologic biopsies. In addition, these samples showed an increased expression of IL-18 (p = 0.0003), IL-4 (p = 0.0055), and IL-12R beta 2 (p = 0.007). Western blot analysis confirmed the expression of IL-12p40 and IL-18. However, for IL-18, we detected only the immature biologically inactive polypeptide. The V alpha 24 transcripts were found increased in the liver (p = 0.0007) where V alpha 24(+) cells were also localized, but decreased in peripheral blood mononuclear cells (p = 0.041). In addition to a type I immune response, NKT cells might play a substantial role in the pathogenesis of type I autoimmune hepatitis in children.