Dataset Information

Quantitative digital pathology reveals association of cell-specific PNPLA3 transcription with NAFLD disease activity.

ABSTRACT:

Background & aims

The I148M variant (rs738409) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) is by far the most important genetic determinant of non-alcoholic fatty liver disease (NAFLD). However, in the context of NAFLD, the transcriptional regulation of PNPLA3 in human liver cells is not known. In this study, we aimed to define the relationship between PNPLA3 transcription and disease characteristics of human NAFLD.

Methods

The abundance of PNPLA3 and collagen 1α (COL1α) transcripts was quantified in situ at single-cell resolution using RNAscope® in 87 patients with NAFLD. We examined the association of PNPLA3 and COL1α transcript levels with NAFLD disease severity, defined by histology.

Results

While the majority of PNPLA3 transcripts were found in hepatocytes, approximately 7% of PNPLA3-positive cells co-express COL1α, representing activated myofibroblasts. There is no association between the rs738409 genotype and the level of PNPLA3 transcript. The overall PNPLA3 transcript abundance is lower in zone 1 hepatocytes, patients with higher body mass index, and those with advanced liver fibrosis. The negative association between the PNPLA3 transcript levels and liver fibrosis is largely driven by COL1α-positive cells. A significant proportion of PNPLA3 mRNA is seen in the nucleus. The cytoplasmic-to-nuclear PNPLA3 mRNA ratio is inversely associated with NAFLD disease activity.

Conclusions

PNPLA3 transcript abundance and nuclear-to-cytoplasmic translocation are negatively associated with hepatic steatosis and NAFLD disease activity, while its abundance in activated myofibroblasts is inversely associated with the stage of liver fibrosis.

Lay summary

A genetic variant in patatin-like phospholipase domain-containing protein 3 (or PNPLA3) is the most important genetic determinant of non-alcoholic fatty liver disease (NAFLD). However, it is not known how transcriptional regulation of the PNPLA3 gene contributes to the disease characteristics of human NAFLD. Herein, we show that the mRNA levels of PNPLA3, particularly in the cytoplasm, are negatively associated with the severity of NAFLD in humans.

SUBMITTER: Sandhu B

PROVIDER: S-EPMC7001539 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Publications

Quantitative digital pathology reveals association of cell-specific <i>PNPLA3</i> transcription with NAFLD disease activity.

Sandhu Bynvant B Perez Matos Maria C MC Tran Stephanie S Zhong Alexander A Csizmadia Eva E Kim Misung M Herman Mark A MA Nasser Imad I Lai Michelle M Jiang Z Gordon ZG

JHEP reports : innovation in hepatology 20190608 3

<h4>Background & aims</h4>The I148M variant (rs738409) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) is by far the most important genetic determinant of non-alcoholic fatty liver disease (NAFLD). However, in the context of NAFLD, the transcriptional regulation of <i>PNPLA3</i> in human liver cells is not known. In this study, we aimed to define the relationship between <i>PNPLA3</i> transcription and disease characteristics of human NAFLD.<h4>Methods</h4>The abundance of <i> ...[more]

PMID: 32039370

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Project description:Background and Objectives: Non-alcoholic fatty liver disease is a worldwide significant public health problem, particularly in patients with type 2 diabetes mellitus. Identifying possible risk factors for the disease is mandatory for a better understandingand management of this condition. Patatin-like phospholipase domain-containing protein 3 (PNPLA3) has been linked to the development and evolution of fatty liver but not to insulin resistance. The aim of this study isto evaluate the relationships between PNPLA3 and fatty liver, metabolic syndrome and subclinical atherosclerosis. Materials and Methods: The study group consisted of patients with type 2 diabetes mellitus without insulin treatment. The degree of liver fat loading was assessed by ultrasonography, and subclinical atherosclerosis was assessed using carotid intima-media thickness (CIMT). PNPLA3 rs738409 genotype determination was performed by high-resolution melting analysis that allowed three standard genotypes: CC, CG, and GG. Results: Among the 92 patients, more than 90% showed various degrees of hepatic steatosis, almost 62% presented values over the normal limit for the CIMT. The majority of the included subjects met the criteria for metabolic syndrome. Genotyping of PNPLA3 in 68 patients showed that the difference between subjects without steatosis and subjects with hepatic steatosis was due to the higher frequency of genotype GG. The CC genotype was the most common in the group we studied and was significantly more frequent in the group of subjects with severe steatosis; the GG genotype was significantly more frequent in subjects with moderate steatosis; the frequency of the CG genotype was not significantly different among the groups.When we divided the group of subjects into two groups: those with no or mild steatosis and those with moderate or severe steatosis it was shown that the frequency of the GG genotype was significantly higher in the group of subjects with moderate or severe steatosis. PNPLA3 genotypes were not associated with metabolic syndrome, subclinical atherosclerosis, or insulin resistance. Conclusions: Our results suggest that PNPLA3 does not independently influence cardiovascular risk in patients with type 2 diabetes mellitus. The hypothesis that PNPLA3 may have a cardioprotective effect requires future confirmation.

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