Transcriptome Analysis on the Inflammatory Cell Infiltration of Nonalcoholic Steatohepatitis in Bama Minipigs Induced by a Long-Term High-Fat, High-Sucrose Diet

Abstract

Long-term adherence to a high-fat, high-calorie diet influences human health and causes obesity, metabolic syndrome and nonalcoholic steatohepatitis (NASH). Inflammation plays a key role in the development of NASH; however, the mechanism of inflammation induced by over-nutrition remains largely unknown. In this study, we fed Bama minipigs a high-fat, high-sucrose diet (HFHSD) for 23 months. The pigs exhibited characteristics of metabolic syndrome and developed steatohepatitis with greatly increased numbers of inflammatory cells, such as lymphocytes (2.27-fold, P<0.05), Kupffer cells (2.59-fold, P<0.05), eosinophils (1.42-fold, P<0.05) and neutrophils (2.77-fold, P<0.05). High-throughput RNA sequencing (RNA-seq) was performed to explore the systemic transcriptome of the pig liver during inflammation. Approximately 18.2 gigabases of raw sequence data were generated, and over 303 million high-quality reads were assembled into 21,126 unigenes. RNA-seq data analysis showed that 822 genes were differentially expressed in liver (P<0.05) between the HFHSD and control groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the process of inflammation involved the inflammatory signal transduction-related toll-like receptor, MAPK, and PPAR signaling pathways; the cytokine-related chemokine signaling, cytokine-cytokine receptor interaction, and IL2, IL4, IL6, and IL12 signaling pathways; the leukocyte receptor signaling-related T cell, B cell, and natural killer cell signaling pathways; inflammatory cell migration and invasion- related pathways; and other pathways. Moreover, we identified several differentially expressed inflammation-related genes between the two groups, including FOS, JUN, TLR7, MYC, PIK3CD, VAV3, IL2RB and IL4R, that could be potential targets for further investigation. Our study suggested that long-term HFHSD induced obesity and liver inflammation, providing basic insight into the molecular mechanism of this condition and laying the groundwork for further studies on obesity and steatohepatitis.

Integrative analysis of blood and gut microbiota data suggests a non-alcoholic fatty liver disease (NAFLD)-related disorder in French SLAdd minipigs

“…This result was especially interesting because the enriched processes were found across each step of the two-hit model 12,13 and because they were often confirmed by more than one analysis method. Furthermore, the pathways identified as enriched showed high levels of agreement with the literature available for humans 13,14,48 and for Bama pigs 15 . These findings indicated a global shift in gene expression and suggested an impact of the disease on the physiological state of the minipigs.…”

“…proinflammatory cytokines 12 . Subsequently, cytokines interact with their receptors to initiate various signalling cascades [14][15][16] . Since NAFLD is linked to cardiac diseases, other processes such as platelet activation are involved 10 .…”

“…To date, rodents have been the pillar for research on obesity, NAFLD and NASH, but physiological differences with humans slow their use 15,17 . Alternative models are being pursued, and the pig is acknowledged as a relevant one because of its anatomical, physiological, and metabolic similarities with humans 15,[17][18][19] .…”

“…To date, rodents have been the pillar for research on obesity, NAFLD and NASH, but physiological differences with humans slow their use 15,17 . Alternative models are being pursued, and the pig is acknowledged as a relevant one because of its anatomical, physiological, and metabolic similarities with humans 15,[17][18][19] . Minipigs show a distinct tendency towards obesity and related pathologies 20 , and several lines are used for their study, such as Ossabaw, Göttingen, and Bama 15,17,21 .…”

“…Alternative models are being pursued, and the pig is acknowledged as a relevant one because of its anatomical, physiological, and metabolic similarities with humans 15,[17][18][19] . Minipigs show a distinct tendency towards obesity and related pathologies 20 , and several lines are used for their study, such as Ossabaw, Göttingen, and Bama 15,17,21 . In the aforementioned papers, the animals were fed specific high-calorie diets, but most minipigs develop obesity even when receiving ad libitum standard chow 1,20,22 .…”