Role of IL-18 in pathogenesis of endometriosis.

BACKGROUND: Endometriosis is a complex disease associated with a wide range of immune responses, including pain, adhesion, exudation of peritoneal fluid, elevation of cytokine levels and generation of autoantibodies. Interleukin (IL)-18 is a strong pleiotropic cytokine known to be involved in various immune diseases. The aim of this study is to elucidate the role of IL-18 in the pathogenesis of endometriosis. METHODS: IL-18 and IL-1beta concentrations were measured in the peritoneal fluid and sera of 39 endometriosis patients and 15 control women. Expression of IL-18 and IL-18 receptor alpha-chain (IL-18Ralpha) was analysed in endometriotic tissues immunohistochemically. The effects of IL-18 on cyclooxygenase (COX)-II gene expression were analysed in peritoneal fluid monocytes and endometriotic cells of endometriosis patients. RESULTS: IL-18 concentrations in the peritoneal fluid of endometriosis patients averaged 592.57 +/- 108.27 pg/ml, significantly higher than 260.50 +/- 55.88 pg/ml in non-endometriotic samples. IL-18 concentrations in the serum did not differ significantly between endometriosis and control patients. Similarly, no significant differences were observed in IL-1beta concentrations in either the peritoneal fluid or the serum. IL-18 and IL-18Ralpha were expressed in endometriotic tissues. IL-18Ralpha expression was also observed in cells infiltrating into the inflammatory area of the endometriosis patients. COX-II was induced in peritoneal fluid monocytes and in endometriotic cells in response to IL-18 stimulation. CONCLUSIONS: The elevation of IL-18 in the peritoneal fluid of endometriosis patients and the induction of COX-II in peritoneal monocytes by IL-18 suggest that IL-18 plays a pathogenic role in endometriosis.

IL-18 and IL-12 induce intestinal inflammation and fatty liver in mice in an IFN-gamma dependent manner.

BACKGROUND: In murine models of inflammatory bowel disease, colonic inflammation is considered to be caused by an aberrant Th1-type immune response. AIM: To investigate if systemic administration of interleukin (IL)-12 and IL-18 to wild-type BALB/c mice induces liver injury and intestinal inflammation, and if pathological changes are observed, what cytokines are involved. METHODS: Mice (BALB/c-wild-type (wt), MRL-lpr/lpr, BALB/c-interferon gamma knock out (IFN-gamma KO), C57BL/6-inducible nitric oxide synthase (iNOS) KO, and BALB/c tumour necrosis factor alpha (TNF-alpha) KO) were injected intraperitoneally each day with IL-12 (20 ng/g/mouse) and/or IL-18 (200 ng/g/mouse). RESULTS: Administration of IL-12 and IL-18 to BALB/c-wt mice induced prominent intestinal mucosal inflammation and fatty liver, leading to piloerection, bloody diarrhoea, and weight loss. IL-12 and IL-18 induced striking elevations in serum levels of IFN-gamma that caused NO production, although increased NO had no exacerbating effect on mice. Moreover, iNOS KO mice, or MRL lpr/lpr mice lacking functional Fas were equally susceptible to IL-12 and IL-18. Administration of IL-12 and IL-18 did not induce TNF-alpha production in wild-type mice, and the same treatment to TNF-alpha KO mice induced intestinal mucosal inflammation. Furthermore, they had diffuse and dense infiltration of small fat droplets in their hepatocytes associated with an increase in serum levels of liver enzymes. In contrast, the same treatment in IFN-gamma KO BALB/c mice and iNOS KO mice did not induce these changes. CONCLUSIONS: Our study strongly indicates that IL-18 together with IL-12 induces intestinal mucosal inflammation in an IFN-gamma dependent but TNF-alpha, NO, and Fas ligand independent manner, and fatty liver is dependent on IFN-gamma and NO.

Direct immunization of malaria DNA vaccine into the liver by gene gun protects against lethal challenge of Plasmodium berghei sporozoite.

The liver is the first target organ for malaria parasites immediately after the bite of an infected mosquito. We studied local immunization of malaria DNA vaccines at the site of the liver using a gene gun as a useful tool for in vivo transfection of foreign genes. A malaria DNA vaccine consisting of the Plasmodium berghei circumsporozoite protein (PbCSP) gene plus the mouse IL-12 gene was bombarded directly by a gene gun into mouse liver once or into the skin twice. A marked protective effect was induced by gene bombardment into the liver (more than 71%) compared with that into the skin (less than 33%). A Th1-type immune response and high production of iNOS were observed in the hepatic lymphocytes from mice bombarded into the liver, resulting in more effective protection compared with those bombarded into the skin. These results provide an important implication on the development of efficient malaria vaccine strategies.

Quantitative analysis of integrated Ed alpha gene expression in C57BL/6 transgenic mice.

We performed quantitative analysis of Ed alpha gene expression in the transgenic mice, created by microinjecting cloned Ed alpha gene fragments into C57BL/6 fertilized eggs. DNA dot-blot analysis revealed that Ed alpha gene-introduced transgenic mice (B6Ed alpha transgenic mice) contain 20 copies per cell of the Ed alpha gene in their genome. RNA dot-blot analysis revealed that the amount of Ed alpha mRNAs in B6Ed alpha transgenic spleen cells is 20-40-fold higher than those in normal BALB/c or (BALB x C57BL/6)F1 (CBF1) spleen cells. However, the amount of Ed alpha molecules expressed on B6Ed alpha transgenic spleen cells was similar to that expressed on normal BALB/c of CBF1 spleen cells on a gene-dose basis. The amount of endogenous Ed alpha mRNA in the B6Ed alpha transgenic spleen cells was almost equal to that of normal B6 spleen cells. Since the cell surface I-E molecule is formed by non-covalent association of E alpha and E beta chain, these results suggest that, in spite of the high expression of integrated Ed alpha gene in the cytoplasm of B6Ed alpha transgenic mice, the amount of Ed alpha gene expression on the cell surface is limited by the amount of endogenous Eb beta gene products.