Background The identification of the cellular and molecular pathways that mediate the development of non-alcoholic steatohepatitis is of crucial importance. Cytokines produced by liver-resident and infiltrating inflammatory cells, play a pivotal role in liver inflammation. The role of the proinflammatory cytokines IL-1α and IL-1β in steatohepatitis remains elusive. Aims & Methods We employed IL-1α and IL-1β-deficient mice and transplanted marrow cells to study the role of liver-resident and bone marrow-derived IL-1 in steatosis and its progression to steatohepatitis. Results Atherogenic diet-induced steatohepatitis in wild-type mice was associated with 16 and 4.6 folds-elevations in mRNA levels of hepatic IL-1α and IL-1β, respectively. In mice deficient in either IL-1α or IL-1β the transformation of steatosis to steatohepatitis and liver fibrosis was markedly reduced. This protective effect in IL-1α-deficient mice was noted despite increased liver cholesterol levels. Deficiency of IL-1α markedly reduced plasma serum amyloid A and steady-state levels of mRNA coding for inflammatory genes (P-selectin, CXCL1, IL-6, TNFα) as well as pro-fibrotic genes (MMP-9 and Collagen) and particularly a 50% decrease in TGFβ (p=0.004). IL-1α mRNA levels were 2 folds lower in IL-1β-deficient mice, and IL-1β transcripts were 3 folds lower in IL-1α-deficient compared to wild-type mice. Hepatic cell derived IL-1α rather than from recruited bone marrow-derived cells is required for steatohepatitis development. Conclusions These data demonstrate the critical role of IL-1α and IL-1β in the transformation of steatosis to steatohepatitis and liver fibrosis in hypercholesterolemic mice. Therefore, the potential of neutralizing IL-1α and/or IL-1β to inhibit development of steatohepatitis should be explored.

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Abstract-To study the possible role of the human lipid-oxidizing enzyme 15-lipoxygenase (15-LO) in atherosclerosis, we overexpressed it specifically in the vascular wall of C57B6/SJL mice by using the murine preproendothelin-1 promoter. The mice overexpressing 15-LO were crossbred with low density lipoprotein (LDL) receptor-deficient mice to investigate atherogenesis. High levels of 15-LO were expressed in the atherosclerotic lesion in the double-transgenic mice as assessed by immunohistochemistry. The double-transgenic, 15-LO-overexpressing, LDL receptor-deficient mice (LDLR Ϫ/Ϫ /15LO) developed significantly larger atherosclerotic lesions at the aortic sinus compared with lesions in the LDL receptor-deficient (LDLR Ϫ/Ϫ ) mice after 3 and 6 weeks (107 000 versus 28 000 m 2 [PϽ0.001] and 121 000 versus 87 000 m 2 [PϽ0.05], respectively) of an atherogenic diet. LDL from the LDLR Ϫ/Ϫ /15LO mice was more susceptible to oxidation than was the LDL from the control LDLR Ϫ/Ϫ mice, as shown by a shorter lag period for copper-induced conjugated diene formation. On the other hand, no differences were found in the levels of serum anti-oxidized LDL antibodies between the study groups. There were also no differences with respect to the density of macrophages and T lymphocytes infiltrating the lesions in both experimental groups. Taken together, these results support the hypothesis that 15-LO overexpression in the vessel wall is associated with enhanced atherogenesis.

Background-Immunization with ␤ 2 -glycoprotein I (␤2GPI), the probable target of autoimmune anticardiolipin antibodies, results in experimental antiphospholipid syndrome in different mouse strains. The present study was undertaken to evaluate the effect of ␤2GPI immunization on the progression of atherosclerosis. Methods and Results-In the first experiment, 3 groups of LDL receptor-deficient (LDL-RD) mice (nϭ15 per group) were immunized with either ␤2GPI or ovalbumin or were not immunized and were fed a chow diet for 12 weeks. In a second experiment, 3 groups of LDL-RD mice (nϭ10 per group) were immunized similarly and fed an atherogenic diet for 6 weeks. All ␤2GPI-immunized mice developed high titers of anti-␤2GPI antibodies as well as a specific lymph node proliferation to ␤2GPI. The average cholesterol levels did not differ between the mice fed similar diets, regardless of the immunization protocol. Atherosclerosis was enhanced in the ␤2GPI-immunized mice (mean aortic lesion, 26 000Ϯ5700 m 2 ) in comparison with their ovalbumin-immunized (mean, 3000Ϯ1099 m 2 ; PϽ0.01) and nonimmunized (mean, 2250Ϯ700 m 2 ; PϽ0.01) littermates. The average lesion size in the ␤2GPI-immunized mice fed an atherogenic diet (mean, 98 000Ϯ8305 m 2 ) was larger than the ovalbumin-immunized mice (mean, 81 250Ϯ12 933 m 2 ; PϭNS) or the nonimmunized controls (mean, 75 625Ϯ7281 m 2 ; PϭNS). The atherosclerotic plaques in the ␤2GPI-immunized mice appeared to be more mature, and denser infiltration of CD4 lymphocytes was present in the subendothelium of the aortic sinuses from this group of mice. Conclusions-The results of the present study provide the first direct evidence for the proatherogenic effect of ␤2GPI immunization and establish a new model for immune-mediated atherosclerosis. (Circulation. 1998;98:1108-1115.)

12/15-LO plays a dominant role in promoting atherogenesis in LDL-R(-/-) mice.

Abstract-Recent data suggest that the immune system is involved in atherogenesis. Thus, interest has been raised as to the possible antigens that could serve as the initiators of the immune reaction. In the current work, we studied the effects of immunization with recombinant heat shock protein-65 (HSP-65) and HSP-65-rich Mycobacterium tuberculosis (MT) on early atherogenesis in C57BL/6J mice fed either a normal chow diet or a high-cholesterol diet (HCD). A rapid, cellular immune response to HSP-65 was evident in mice immunized with HSP-65 or with MT but not in the animals immunized with phosphate-buffered saline (PBS) alone. Early atherosclerosis was significantly enhanced in HCD-fed mice immunized with HSP-65 (nϭ10; mean aortic lesion size, 45 417Ϯ9258 m 2 ) or MT (nϭ15; 66 350Ϯ6850 m 2 ) compared with PBS-injected (nϭ10; 10 028Ϯ3599 m 2 ) or nonimmunized (nϭ10; 9500Ϯ2120 m 2 ) mice. No fatty streak lesions were observed in mice fed a chow diet regardless of the immunization protocol applied. Immunohistochemical analysis of atherosclerotic lesions from the HSP-65-and MT-immunized mice revealed infiltration of CD4 lymphocytes compared with the relatively lymphocyte-poor lesions in the PBS-treated or nonimmunized mice. Direct immunofluorescence analysis of lesions from HSP-65-and MT-immunized mice fed an HCD exhibited extensive deposits of immunoglobulins compared with the fatty streaks in the other study groups, consistent with the larger and more advanced lesions found in the former 2 groups. This model, which supports the involvement of HSP-65 in atherogenesis, furnishes a valuable tool to study the role of the immune system in atherogenesis.

When grown under defined conditions DunaileIIa bardawil accumulates a high concentration of (3-carotene, which is composed primarily of two isomers, all-trans and 9-cis (3-carotene. The high (-carotene Dunaliella bardawil, Ben-Amotz and Avron, and Dunaliella salina Teod., were shown to accumulate very large amounts of (3-carotene when grown under defined growth conditions (1-4, 1 1). The massively accumulated (3-carotene is concentrated in oily globules located in the interthylakoid space of the chloroplast and is composed of two major stereoisomers: all-trans and 9-cis (3-carotene (3, 5). High f(-carotene containing D. bardawil was shown to be strongly protected against damage induced by excessive irradiation (4).It is generally believed that the intrathylakoid (3-carotene protects plants by quenching damaging reagents (e.g., singlet oxygen) produced by excessive excitation of Chl (7-10). However, because of its location outside the thylakoids, the massively accumulated (-carotene

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