SnRNA-Seq of Pancreas Revealed the Dysfunction of Endocrine and Exocrine Cells in Transgenic Pigs with Prediabetes

Molecular pathological characteristics and mechanisms of the liver in metabolic disease-susceptible transgenic pigs

AIMS

This study aimed to explore the molecular pathological mechanisms of the liver in metabolic disease-susceptible transgenic pigs via multiomics analysis.

MATERIALS AND METHODS

The triple-transgenic (PNPLA3I148M-GIPRdn-hIAPP) pig model (TG pig) was successfully constructed in our laboratory via the CRISPR/Cas9 technique previously described. Wild-type (WT) pigs and TG pigs after 2 or 12 months of high-fat and high-sucrose diet (HFHSD) induction (WT2, TG2, WT12, and TG12 groups, respectively) were used as materials. The transcriptome, metabolome, and lipidome were used to investigate the molecular mechanisms of the liver in pigs.

KEY FINDINGS

The TG2 pigs presented mild metaflammation and insulin resistance (IR) which was similar to WT12 pigs. Compared with the other three groups, the TG12 pigs presented severe hepatocyte ballooning, fat deposition, and portal area fibrosis. The transcriptome data suggested that the TG2 pigs presented upregulated gene expression in the extracellular matrix (ECM). The TG12 pigs presented more severe metaflammation and exhibited imbalanced glycolipid metabolism. Interestingly, genes such as ETNPPL, GABBR2, and BMP8B might be key regulatory targets for liver injury. The metabolome and lipidome suggested that long-chain polyunsaturated fatty acids (LCPUFAs) and phospholipids with corresponding LCPUFAs were remodelled. Importantly, bis(monoacylglycerol) phosphates (BMPs) and sulfatides (SLs) could be the key regulatory metabolites in liver injury.

SIGNIFICANCE

ETNPPL, GABBR2, and BMP8B might be potential therapeutic targets for liver injury. BMPs and SLs might be biomarkers for the diagnosis and treatment of liver diseases.

Deficiency of SLC26A3 promotes jejunal barrier damage in metabolic disease-susceptible transgenic pigs

Intestinal disorders are common in metabolic syndrome. However, their pathogenesis is still not fully understood. Pig and human intestines are highly similar in terms of associated metabolic processes. Here, we successfully constructed a metabolic disease-susceptible transgenic (TG) Bama pig model by knocking in three humanized disease risk genes with the CRISPR/Cas9 technique to assess its potential as a model for human intestinal diseases and explore the possible pathological mechanisms involved. We found that jejunal barrier integrity was disrupted and that the infiltration of inflammatory cells increased in TG pigs after high-fat and high-sucrose diet (HFHSD) treatment. We revealed significant differences in the transcriptome, associated microbiome profiles and microbial metabolite short-chain fatty acid (SCFA) content of the jejunum of TG pigs. Notably, we found that SLC26A3 was significantly downregulated in TG pigs. Knockdown or overexpression of the SLC26A3 gene in IPEC-J2 cells significantly affected the expression of MUC2, MUC13 and occludin. Furthermore, in vitro experiments further verified that CDX2 directly regulated the expression of SLC26A3. Mechanistically, CDX2 mediated intestinal barrier function by enhancing the expression of SLC26A3 by binding to its promoter region between -1120 and - 1070 bp. TG pigs represent a promising model that provides new insights into preclinical research on human intestinal metabolic diseases associated with metabolic disorders and revealed that SLC26A3 may be a potential therapeutic target for intestinal metabolic diseases.

Advances in single-cell transcriptomics in animal research

Understanding biological mechanisms is fundamental for improving animal production and health to meet the growing demand for high-quality protein. As an emerging biotechnology, single-cell transcriptomics has been gradually applied in diverse aspects of animal research, offering an effective method to study the gene expression of high-throughput single cells of different tissues/organs in animals. In an unprecedented manner, researchers have identified cell types/subtypes and their marker genes, inferred cellular fate trajectories, and revealed cell‒cell interactions in animals using single-cell transcriptomics. In this paper, we introduce the development of single-cell technology and review the processes, advancements, and applications of single-cell transcriptomics in animal research. We summarize recent efforts using single-cell transcriptomics to obtain a more profound understanding of animal nutrition and health, reproductive performance, genetics, and disease models in different livestock species. Moreover, the practical experience accumulated based on a large number of cases is highlighted to provide a reference for determining key factors (e.g., sample size, cell clustering, and cell type annotation) in single-cell transcriptomics analysis. We also discuss the limitations and outlook of single-cell transcriptomics in the current stage. This paper describes the comprehensive progress of single-cell transcriptomics in animal research, offering novel insights and sustainable advancements in agricultural productivity and animal health.

Excessive Tryptophan and Phenylalanine Induced Pancreatic Injury and Glycometabolism Disorder in Grower-finisher Pigs

BACKGROUND

The increase in circulating insulin levels is associated with the onset of type 2 diabetes (T2D), and the levels of branched-chain amino acids and aromatic amino acids (AAAs) are altered in T2D, but whether AAAs play a role in insulin secretion and signaling remains unclear.

OBJECTIVES

This study aimed to investigate the effects of different AAAs on pancreatic function and on the use of insulin in finishing pigs.

METHODS

A total of 18 healthy finishing pigs (Large White) with average body weight of 100 ± 1.15 kg were randomly allocated to 3 dietary treatments: Con, a normal diet supplemented with 0.68% alanine; Phe, a normal diet supplemented with 1.26% phenylalanine; and Trp, a normal diet supplemented with 0.78% tryptophan. The 3 diets were isonitrogenous. There were 6 replicates in each group.

RESULTS

Herein, we investigated the effects of tryptophan and phenylalanine on pancreatic function and the use of insulin in finishing pigs and found that the addition of tryptophan and phenylalanine aggravated pancreatic fat deposition, increased the relative content of saturated fatty acids, especially palmitate (C16:0) and stearate (C18:0), and the resulting lipid toxicity disrupted pancreatic secretory function. We also found that tryptophan and phenylalanine inhibited the growth and secretion of β-cells, downregulated the gene expression of the PI3K/Akt pathway in the pancreas and liver, and reduced glucose utilization in the liver.

CONCLUSIONS

Using fattening pigs as a model, multiorgan combined analysis of the insulin-secreting organ pancreas and the main insulin-acting organ liver, excessive intake of tryptophan and phenylalanine will aggravate pancreatic damage leading to glucose metabolism disorders, providing new evidence for the occurrence and development of T2D.