Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jun;20(2):220-227.
doi: 10.26574/maedica.2025.20.2.220.

Innate Immunity Receptor TLR9 Drives Erythrocyte Cholesterol and Ferroprotin Accumulation in a Glutaminase-Independent Manner. Implications for Metabolic Associated Fatty Liver Disease

Konstantinos Mimidis  1 , Zoi Kyriakou  2 , Nikolaos Politis  2 , Panagiotis Veniamis  2 , Dimitris Vlachos  2 , Tentes Ioannis  2 , Konstantinos Anagnostopoulos  2 , Charalampos Papadopoulos  2
Affiliations

Innate Immunity Receptor TLR9 Drives Erythrocyte Cholesterol and Ferroprotin Accumulation in a Glutaminase-Independent Manner. Implications for Metabolic Associated Fatty Liver Disease

Konstantinos Mimidis et al. Maedica (Bucur). 2025 Jun.

Abstract

Background: During metabolic associated fatty liver disease (MAFLD), lipotoxicity induces toll-like receptor 9 (TLR9) upregulation and mitochondrial DNA-induced TLR9 activation in the liver, driving metabolic hepatic inflammation. We wondered whether there is augmented erythrocyte TLR9 in MAFLD and we explored the effect of erythrocyte TLR9 activation on cholesterol and sphingomyelin content, glutaminase activity and TLR9, ferroportin and monocyte chemoattractant protein 1 (MCP-1) levels.

Methods: Twenty-four patients (15 men and nine women) with MAFLD and nine healthy controls (four men and five women) were enrolled. Erythrocytes were isolated from EDTA-containing blood. Protein levels were measured in erythrocyte lysates (Triton X-100 0.1% v/v), erythrocyte membranes (isolated by hypotonic lysis) with enzyme-linked immunosorbent assays, whereas lipids and enzyme activities were measured in erythrocyte hemoglobin-free membranes by a semi-quantitative thin layer chromatography and assay kits, respectively.

Results: The total but not surface levels of TLR9 were increased (p=0.002) in erythrocytes of MAFLD patients. Erythrocyte TLR9 activation drove cholesterol and ferroportin-1 accumulation, but not glutaminase-1 upregulation. Toll-like receptor 9 activation did not induce a significant change on the levels of TLR9 and MCP-1.

Conclusions: Erythrocyte TLR9 is upregulated in MAFLD patients and drives cholesterol and ferroportin-1 accumulation in a glutaminase-independent manner. Augmented erythrocyte TLR9 could participate in metabolic inflammation during MAFLD.

PubMed Disclaimer

Conflict of interest statement

None declared.

References

    1. Younossi ZM, Koenig AB, Abdelatif D, et al. Global epidemiology of nonalcoholic fatty liver disease-Meta-analytic assessment of prevalence, incidence, and outcomes. Hepatol Baltim Md. 2016;64:73–84. - PubMed
    1. Papadopoulos C, Tentes I, Papazoglou D, et al. Lysophospholipid Metabolism and Signalling in Non-Alcoholic Fatty Liver Disease. Folia Med (Plovdiv) 2022;64:7–12. - PubMed
    1. Sawada K, Ohtake T, Hasebe T, et al. Augmented hepatic Toll-like receptors by fatty acids trigger the pro-inflammatory state of non-alcoholic fatty liver disease in mice. Hepatol Res. 2014;44:920–934. - PubMed
    1. Mridha AR, Haczeyni F, Yeh MM, et al. TLR9 is up-regulated in human and murine NASH: pivotal role in inflammatory recruitment and cell survival. Clin Sci (Lond) 2017;131:2145–2159. - PubMed
    1. Gao Y, Wang Y, Liu H, et al. Mitochondrial DNA from hepatocytes induces upregulation of interleukin-33 expression of macrophages in nonalcoholic steatohepatitis. Dig Liver Dis. 2020;52:637–643. - PubMed

LinkOut - more resources