Liver Injury And The Role Of It In IgA Nephropathy Rat Model Induced By Oral Immunization

Objectives:To investigate the liver injury caused by IgA nephropathy (IgAN)-modelingagents by observing the pathological changes of the liver in the oralimmunization-induced IgAN rat model; to explore the role of liver in the oralimmunization-induced IgAN by comparing the relationship between liver injury andintestinal injury, in hope of providing a new way of thinking for the elucidation ofIgAN pathogenesis and for IgAN treatment.Methods:Twenty-eight female SD rats were randomly divided into four groups: normalcontrol group, IgAN model group, rhein treatment group and rhein prevention group(n=7). A combination of bovine serum albumin (BSA)+lipopolysaccharide (LPS)+carbon tetrachloride (CCl4) was applied to establish a rat model of IgAN. Intestineand liver specimens were taken as soon as the animals were sacrificed at the end ofWeek10. Pathological changes of the intestine and liver were examined under lightmicroscopy after H&E staining; ultrastructural changes of the liver were examinedunder transparent electronic microscopy; hepatic and renal IgA depositions weredetected using immunofluorescence method; and the expression levels of liver TLR4,TNF-αand CD68were assayed by immunohistochemistry. The integral opticaldensities (IOD) of TLR4and TNF-αwere measured using an image analysis system;the number density, volume density and average volume of CD68positive cells werecalculated with stereological methods, and statistical analyses were performed toanalyze the significance of the differences between groups.Results:1. Histopathological examination showed that the rat liver in the normal controlgroup exhibited integral structure and normal intrahepatic cell morphology, withoutinflammatory cell infiltration was seen; inflammatory cell infiltration, steatosis andeven necrosis of hepatocytes, and a small amount of fiber hyperplasia in portal areawere seen in liver slices in the IgAN model group; a small amount of fiber hyperplasia in portal area, and hepatocyte proliferation (dual-core, large volume ofhepatocytes) were seen in the rhein treatment group and the rhein prevention group.For the small intestine in the normal control group, the intestinal villi presentednormal morphology with no defect, the epithelial cells arranged in neat rows, and noinflammatory cell infiltration was seen; in the IgAN model group, small intestinalvilli became shorter and thinner, the space between villi widened, part of theepithelium was absent, inflammatory cell infiltration could be seen in lamina propria;compared with the IgAN model group, the degree of injury in the rhein treatmentgroup and the rhein prevention group was significantly reduced. The trend of theseverity of liver injury was consistent with that of intestinal injury.2. Ultrastructural observations showed that the liver of normal control rats had cellnuclei of normal morphology, rich cytoplasma, and mitochondria of normalmorphology and integral structure; a few lipid droplets and swelling and evenvacuolized mitochondria could be seen in the hepatocytes of the IgAN model rats;compared with the IgAN model group, the above ultrastructural lesions werealleviated in the rhein treatment group and the rhein prevention group.3. IgA immunofluorescence detection showed that no or only weak IgAfluorescence was seen in the rat liver of the normal control group; a large amount ofbright green granular IgA fluorescence could be seen in the liver sinusoids in theIgAN model group; compared with the IgAN model group, the liver IgA fluorescentparticles in rhein treatment group and the rhein prevention group decreasedsignificantly. No IgA immunofluorescence was seen in the kidney of normal controlgroup; much bright green granular IgA fluorescence could be seen in the glomerularmesangial area in the IgAN model group; glomerular mesangial IgA fluorescentparticles decreased in the rhein treatment group and the rhein prevention groupcompared with the IgAN model group.4. Compared with the normal control group, the expressions of liver TLR4proteinand TNF-α in the IgAN model group were significantly increased (P <0.01);compared with the IgAN model group, the expressions of liver TLR4protein andTNF-αin the rhein treatment group and rhein prevention group were significantlyreduced (P <0.01); the TNF-αexpression in the rhein prevention group was less than that in the rhein treatment group (P <0.05).5. Compared with the normal control group, the number density, volumedensity and average volume of liver CD68+cells of the IgAN model group rats wereall increased significantly (P <0.05or P <0.01). Compared with the IgAN modelgroup, the number density of liver CD68+cells was significantly reduced (P <0.01)while the average volume increased (P <0.05) in the rhein treatment group and rheinprevention group.Conclusions:1. The application of BSA+CCl4+LPS to establish an IgA nephropathy modelcan cause liver injury, and a large mount of IgA deposition and a large number ofCD68+macrophages appears in the liver.2. The liver injury is associated with intestinal mucosal barrier injury.3. The liver injury may due to LPS-TLR4-TNF-α pathway.4. Rhein can reduce liver injury by protecting the intestinal mucosal barrier,reduce hepatic IgA deposition and enhance the function of CD68+macrophages.5. Liver injury may play a role in the process of the formation of IgAnephropathy.