Liver inflammation at the time of spinal cord injury enhances intraspinal pathology, liver injury, metabolic syndrome and locomotor deficits

The current high obesity rates mean that neurological injuries are increasingly sustained on a background of systemic pathology, including liver inflammation, which likely has a negative impact on outcomes. Because obesity involves complex pathology, the effect of hepatic inflammation alone on neurological recovery is unknown. Thus, here we used a gain-of-function model to test if liver inflammation worsens outcome from spinal cord injury (SCI) in rats. Results show liver inflammation concomitant with SCI exacerbated intraspinal pathology and impaired locomotor recovery. Hepatic inflammation also potentiated SCI-induced non-alcoholic steatohepatitis (NASH), endotoxemia and insulin resistance. Circulating and cerebrospinal levels of the liver-derived protein Fetuin-A were higher in SCI rats with liver inflammation, and, when microinjected into intact spinal cords, Fetuin-A caused macrophage activation and neuron loss. Thus, liver inflammation functions as a disease modifying factor to impair recovery from SCI, and Fetuin-A is a potential neuropathological mediator. Since SCI alone induces acute liver inflammation, the liver may be a novel clinical target for improving recovery from SCI.

Nonalcoholic Steatohepatitis: Histopathology Basics Within a Broader Context

Nonalcoholic fatty liver disease (NAFLD) is a major health concern and the prevalence continues to increase in many industrialized and developing countries around the world. NAFLD affects adults and children. NAFLD-related cirrhosis is expected to become the top indication for liver transplantation in the near future, and the incidence of NAFLD-related hepatocellular carcinoma is also increasing. Nonalcoholic steatohepatitis is the more severe form of NAFLD. The pathogenesis of NALFD/nonalcoholic steatohepatitis is complex and new concepts continue to evolve. The diagnosis and categorization of nonalcoholic steatohepatitis currently rests on hepatopathologists. Accurate morphologic interpretation is important for therapeutic, prognostic, and investigational purposes.

Animal models of NAFLD from the pathologist's point of view. Biochim Biophys Acta Mol Basis Dis. 2019;1865:929-942. [PMID: 29746920 DOI: 10.1016/j.bbadis.2018.04.024]

Fatty liver disease is a multifactorial world-wide health problem resulting from a complex interplay between liver, adipose tissue and intestine and initiated by alcohol abuse, overeating, various types of intoxication, adverse drug reactions and genetic or acquired metabolic defects. Depending on etiology fatty liver disease is commonly categorized as alcoholic or non-alcoholic. Both types may progress from simple steatosis to the necro-inflammatory lesion of alcoholic (ASH) and non-alcoholic steatohepatitis (NASH), respectively, and finally to cirrhosis and hepatocellular carcinoma. Animal models are helpful to clarify aspects of pathogenesis and progression. Generally, they are classified as nutritional (dietary), toxin-induced and genetic, respectively, or represent a combination of these factors. Numerous reviews are dealing with NASH animal models designed to imitate as closely as possible the metabolic situation associated with human disease. This review focuses on currently used mouse models of NASH with particular emphasis on liver morphology. Despite metabolic similarities most models (except those with chemically or genetically induced porphyria or keratin 18-deficiency) fail to develop the morphologic key features of NASH, namely hepatocyte ballooning and formation of histologically and immunohistochemically well-defined Mallory-Denk-Bodies (MDBs). Although MDBs are not universally detectable in ballooned hepatocytes in NASH their experimental reproduction and analysis may, however, significantly contribute to our understanding of important pathogenic aspects of NASH despite the obvious differences in etiology.

A diet-induced animal model of non-alcoholic fatty liver disease and hepatocellular cancer

BACKGROUND & AIMS

The lack of a preclinical model of progressive non-alcoholic steatohepatitis (NASH) that recapitulates human disease is a barrier to therapeutic development.

METHODS

A stable isogenic cross between C57BL/6J (B6) and 129S1/SvImJ (S129) mice were fed a high fat diet with ad libitum consumption of glucose and fructose in physiologically relevant concentrations and compared to mice fed a chow diet and also to both parent strains.

RESULTS

Following initiation of the obesogenic diet, B6/129 mice developed obesity, insulin resistance, hypertriglyceridemia and increased LDL-cholesterol. They sequentially also developed steatosis (4-8weeks), steatohepatitis (16-24weeks), progressive fibrosis (16weeks onwards) and spontaneous hepatocellular cancer (HCC). There was a strong concordance between the pattern of pathway activation at a transcriptomic level between humans and mice with similar histological phenotypes (FDR 0.02 for early and 0.08 for late time points). Lipogenic, inflammatory and apoptotic signaling pathways activated in human NASH were also activated in these mice. The HCC gene signature resembled the S1 and S2 human subclasses of HCC (FDR 0.01 for both). Only the B6/129 mouse but not the parent strains recapitulated all of these aspects of human NAFLD.

CONCLUSIONS

We here describe a diet-induced animal model of non-alcoholic fatty liver disease (DIAMOND) that recapitulates the key physiological, metabolic, histologic, transcriptomic and cell-signaling changes seen in humans with progressive NASH.

LAY SUMMARY

We have developed a diet-induced mouse model of non-alcoholic steatohepatitis (NASH) and hepatic cancers in a cross between two mouse strains (129S1/SvImJ and C57Bl/6J). This model mimics all the physiological, metabolic, histological, transcriptomic gene signature and clinical endpoints of human NASH and can facilitate preclinical development of therapeutic targets for NASH.

B cell-activating factor is associated with the histological severity of nonalcoholic fatty liver disease

PURPOSE

B cell-activating factor (BAFF) is expressed in adipocytes and affects lipogenesis and insulin sensitivity. In addition, the BAFF receptor is expressed in visceral adipose tissue and liver. The aim of this study was to analyze serum BAFF levels in patients with nonalcoholic steatohepatitis (NASH) and simple steatosis (SS) and to compare their respective clinical and histological findings.

METHODS

A total of 96 patients with nonalcoholic fatty liver disease (20 with SS and 76 with NASH) were enrolled and their serum BAFF levels were analyzed. Comprehensive blood chemistry analysis and histological examination of liver samples were also conducted.

RESULTS

Serum BAFF levels were higher in patients with NASH than in those with SS (p = 0.016). NASH patients with ballooning hepatocytes and advanced fibrosis had higher levels of BAFF in sera (p = 0.016 and p = 0.006, respectively). In addition, the prevalence of NASH increased significantly as the serum BAFF level increased (p = 0.004). Higher serum BAFF levels were found to be an independent risk factor for development of NASH (OR 1.003, 95% CI 1.0003-1.006; p = 0.047).

CONCLUSIONS

Nonalcoholic steatohepatitis patients had higher levels of serum BAFF than patients with SS, and higher levels were associated with the presence of hepatocyte ballooning and advanced fibrosis. The serum BAFF level may be a useful tool for distinguishing NASH from SS.