Nd elevated expression of inflammatory cytokines upon stimulation with several TLR ligands [11,14,15]. Moreover, IRAK-M2/2 mice had increased inflammatory responses to bacterial infection [11]. Kupffer cells, the liver resident macrophages, usually express CD68, contribute to the most of the 
effects of alcohol-associated liver damage including alcohol-induced oxidative stress on thehepatocytes [16,17] and enhanced inflammatory cytokine production [18,19]. Furthermore, alcohol exposure increased gut permeability, which led to an elevated level of intestinal endotoxin (LPS) in the liver and circulation [20,21]. It is known that TLR4 is the receptor for LPS [22,23] and therefore, it is not surprising that TLR4 plays an important role in ALD [24,25,26,27]. In the current study, we intended to establish a murine model of acute alcoholic liver damage using wild type and IRAK-M deficient B6 mice in order to investigate the role of IRAK-M, the negative regulator of innate immune system, in alcohol-induced liver damage. We have found that IRAK-M deficient mice appeared to be more susceptible to alcohol-induced liver damage that was accompanied by enhanced inflammation, gut permeability and altered intestinal microbiota.Materials and Methods Animals and ReagentsWild type C57BL/6 mice were [DTrp6]-LH-RH obtained originally from the Jackson Laboratories (Bar Harbor, Maine) and maintained at the Yale Animal Facility. IRAK-M2/2 mice were generated as described previously [11] and back-crossed on C57BL/6 background for 10 generations (http://jaxmice.jax.org/strain/007016. html). The genetic purity of the IRAK-M2/2 mice was further confirmed by mouse genome SNP analysis using 1449 Illumina beadchip (www.dartmouse.org). All the mice used in this studyIRAK-M Regulates Liver InjuryFigure 1. Genome analysis. The genetic purity of IRAK-M2/2 B6 mice was analyzed with genomic DNA from IRAK-M2/2 B6 mice (breeders). WT B6 mice from the Jackson Docosahexaenoyl ethanolamide Laboratory were used as controls. Genomic SNP analysis of one WT control (upper) and one IRAK-M2/2 mouse (lower) is shown in the figure. doi:10.1371/journal.pone.0057085.gIRAK-M Regulates Liver InjuryIRAK-M Regulates Liver InjuryFigure 2. Liver injury after alcohol treatment in IRAK-M2/2 mice. To induce alcoholic liver damage, mice were fed with alcohol as described in Materials Methods. (A) Serum ALT levels in control (CTL) and 10 alcohol treated (ALC, without binge) IRAK-M2/2 mice (red) compared with wild type B6 mice (blue). Data shown are from one of 4 experiments. (B) Serum ALT levels in control (CTL) and alcohol (10 and binge) treated (ALC) IRAKM2/2 mice (red) compared with wild type B6 mice (blue). Data are from pooled 2 experiments. (C-F): Liver tissue was stained with standard H E and liver histology was viewed under a light microscope (20X) by a blinded investigator. Data represent one of two independent experiments (n = 3? per group in each experiment). (C+D) Liver histology from a WT B6 mouse without (C) and with binge ALC exposure (D). (E+F) Liver histology from an IRAK-M2/2 B6 mouse without (E) and with binge ALC exposure (F). (G) Absolute number of LMNCs per gram liver tissue in control and alcohol treated mice. More infiltrating lymphocytes 
were found in IRAK-M2/2 mice (red) compared with wild type B6 mice (blue) after binge alcohol treatment. Data were from 2 pooled experiments and error bars represent the SD of samples within a group. The experiment was repeated twice. *P,0.05, **P,0.01, Two way ANOVA analysis. do.Nd elevated expression of inflammatory cytokines upon stimulation with several TLR ligands [11,14,15]. Moreover, IRAK-M2/2 mice had increased inflammatory responses to bacterial infection [11]. Kupffer cells, the liver resident macrophages, usually express CD68, contribute to the most of the effects of alcohol-associated liver damage including alcohol-induced oxidative stress on thehepatocytes [16,17] and enhanced inflammatory cytokine production [18,19]. Furthermore, alcohol exposure increased gut permeability, which led to an elevated level of intestinal endotoxin (LPS) in the liver and circulation [20,21]. It is known that TLR4 is the receptor for LPS [22,23] and therefore, it is not surprising that TLR4 plays an important role in ALD [24,25,26,27]. In the current study, we intended to establish a murine model of acute alcoholic liver damage using wild type and IRAK-M deficient B6 mice in order to investigate the role of IRAK-M, the negative regulator of innate immune system, in alcohol-induced liver damage. We have found that IRAK-M deficient mice appeared to be more susceptible to alcohol-induced liver damage that was accompanied by enhanced inflammation, gut permeability and altered intestinal microbiota.Materials and Methods Animals and ReagentsWild type C57BL/6 mice were obtained originally from the Jackson Laboratories (Bar Harbor, Maine) and maintained at the Yale Animal Facility. IRAK-M2/2 mice were generated as described previously [11] and back-crossed on C57BL/6 background for 10 generations (http://jaxmice.jax.org/strain/007016. html). The genetic purity of the IRAK-M2/2 mice was further confirmed by mouse genome SNP analysis using 1449 Illumina beadchip (www.dartmouse.org). All the mice used in this studyIRAK-M Regulates Liver InjuryFigure 1. Genome analysis. The genetic purity of IRAK-M2/2 B6 mice was analyzed with genomic DNA from IRAK-M2/2 B6 mice (breeders). WT B6 mice from the Jackson Laboratory were used as controls. Genomic SNP analysis of one WT control (upper) and one IRAK-M2/2 mouse (lower) is shown in the figure. doi:10.1371/journal.pone.0057085.gIRAK-M Regulates Liver InjuryIRAK-M Regulates Liver InjuryFigure 2. Liver injury after alcohol treatment in IRAK-M2/2 mice. To induce alcoholic liver damage, mice were fed with alcohol as described in Materials Methods. (A) Serum ALT levels in control (CTL) and 10 alcohol treated (ALC, without binge) IRAK-M2/2 mice (red) compared with wild type B6 mice (blue). Data shown are from one of 4 experiments. (B) Serum ALT levels in control (CTL) and alcohol (10 and binge) treated (ALC) IRAKM2/2 mice (red) compared with wild type B6 mice (blue). Data are from pooled 2 experiments. (C-F): Liver tissue was stained with standard H E and liver histology was viewed under a light microscope (20X) by a blinded investigator. Data represent one of two independent experiments (n = 3? per group in each experiment). (C+D) Liver histology from a WT B6 mouse without (C) and with binge ALC exposure (D). (E+F) Liver histology from an IRAK-M2/2 B6 mouse without (E) and with binge ALC exposure (F). (G) Absolute number of LMNCs per gram liver tissue in control and alcohol treated mice. More infiltrating lymphocytes were found in IRAK-M2/2 mice (red) compared with wild type B6 mice (blue) after binge alcohol treatment. Data were from 2 pooled experiments and error bars represent the SD of samples within a group. The experiment was repeated twice. *P,0.05, **P,0.01, Two way ANOVA analysis. do.