The Predictive Role of Tenascin-C and Cellular Communication Network Factor 3 (CCN3) in Post Hepatectomy Liver Failure in a Rat Model and 50 Patients Following Partial Hepatectomy

Evaluating the mitochondrial structure and gene expression profile of regenerated liver tissues in mice after 85% partial hepatectomy

Background

Partial hepatectomy (PH) is the primary method used for treating liver injury and transplantation. The regeneration process after hepatectomy requires an adequate energy supply, and mitochondria serve as the primary source of energy. Alterations in genes related to the respiratory chain complex may impact the liver regeneration process. The aim of this study was the changes in mitochondrial structure and mitochondrial function in 85% PH.

Methods

A PH (up to 85%) model was developed using male C57BL/6 mice, and the regenerated liver tissue was harvested after 24 hours. Hematoxylin and eosin staining and transmission electron microscopy were used for morphological studies. In terms of proliferation, a positive proliferating cell nuclear antigen (PCNA) rate was detected via immunohistochemistry. Real-time polymerase chain reaction was performed to identify differentially expressed genes (DEGs), which were screened using a P value of <0.05 and a |fold change| of ≥1.5. The Hiplot online tool was used for generating a volcano plot and conducting correlation analyses. R software was employed for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses for the DEGs. A combined Search Tool for the Retrieval of Interacting Genes/Proteins (STRING)-Cytoscape method was used for protein-protein interaction (PPI) network analyses, whereas cytoHubba was used to the screen core DEGs.

Results

After 85% PH, we observed steatosis, an increased PCNA positivity rate, mitochondrial swelling, and a reduced number of cristae due to cristae disintegration. We screened 30 DEGs that were associated with different processes, including oxidation-reduction, oxidoreductase activity, electron transfer activity, organelle envelope, inner mitochondrial membrane processes, and oxidative phosphorylation as well as those involved in nonalcoholic fatty liver disease (NAFLD). We identified a total of six hub genes: COX4I1, ATP5B, UQCRC2, CYC1, ATP5O, and ATP5A1.

Conclusions

The 85% PH model promotes mitochondrial complex protein expression, thereby providing energy for liver regeneration. The enriched genes were associated with oxidation-reduction, electron transfer activity, and inner mitochondrial membrane processes.

Significance of CCNs in liver regeneration

The liver has an inherent regenerative capacity via hepatocyte proliferation after mild-to-modest damage. When hepatocytes exhaust their replicative ability during chronic or severe liver damage, liver progenitor cells (LPC), also termed oval cells (OC) in rodents, are activated in the form of ductular reaction (DR) as an alternative pathway. LPC is often intimately associated with hepatic stellate cells (HSC) activation to promote liver fibrosis. The Cyr61/CTGF/Nov (CCN) protein family consists of six extracellular signaling modulators (CCN1-CCN6) with affinity to a repertoire of receptors, growth factors, and extracellular matrix proteins. Through these interactions, CCN proteins organize microenvironments and modulate cell signalings in a diverse variety of physiopathological processes. In particular, their binding to subtypes of integrin (αvβ5, αvβ3, α6β1, αvβ6, etc.) influences the motility and mobility of macrophages, hepatocytes, HSC, and LPC/OC during liver injury. This paper summarizes the current understanding of the significance of CCN genes in liver regeneration in relation to hepatocyte-driven or LPC/OC-mediated pathways. Publicly available datasets were also searched to compare dynamic levels of CCNs in developing and regenerating livers. These insights not only add to our understanding of the regenerative capability of the liver but also provide potential targets for the pharmacological management of liver repair in the clinical setting. Ccns in liver regeneration Restoring damaged or lost tissues requires robust cell growth and dynamic matrix remodeling. Ccns are matricellular proteins highly capable of influencing cell state and matrix production. Current studies have identified Ccns as active players in liver regeneration. Cell types, modes of action, and mechanisms of Ccn induction may vary depending on liver injuries. Hepatocyte proliferation is a default pathway for liver regeneration following mild-to-modest damages, working in parallel with the transient activation of stromal cells, such as macrophages and hepatic stellate cells (HSC). Liver progenitor cells (LPC), also termed oval cells (OC) in rodents, are activated in the form of ductular reaction (DR) and are associated with sustained fibrosis when hepatocytes lose their proliferative ability in severe or chronic liver damage. Ccns may facilitate both hepatocyte regeneration and LPC/OC repair via various mediators (growth factors, matrix proteins, integrins, etc.) for cell-specific and context-dependent functions.

Tenascin-C Participates Pulmonary Injury Induced by Paraquat Through Regulating TLR4 and TGF-β Signaling Pathways

This study was conducted to investigate the role of Tenascin-C (TNC) in paraquat (PQ)-induced lung injury in vivo and in vitro and explore its related mechanism during this process. Six- to eight-week-old male C57BL/6 mice were injected with 30 mg/kg PQ by intraperitoneal injection and sacrificed on 2 days, 7 days, 14 days, and 28 days after PQ administration. In vivo, we detected the expression of TNC at all time points of lung tissues in mice by reverse transcription-quantitative-polymerase chain reaction, western blotting, and immunohistochemistry. Expression of TLR4, NF-κB p65, TGF-β1, and α-SMA in lung tissues have also been tested. In vitro, siRNA was used to knock down TNC expression in A549 cells and TLR4, NF-κB p65, and TGF-β1 expressions were examined after PQ exposure. TNC expression increased in both lung tissues of mice model and A549 cells after PQ administration. In vivo, TNC mostly located at the extracellular matrix of thickened alveolar septum, especially at sites of injury, together with the increasing of TLR4, NF-κB p65, TGF-β1, and α-SMA. In vitro, PQ exposure also increased the expressions of TLR4, NF-κB p65, and TGF-β1 in A549 cells, but knocking down TNC gene expression obviously down-regulated the expressions of TLR4, NF-κB p65, NF-κB Pp65, and TGF-β1. The results of this study demonstrate, for the first time, that TNC participates in the development of lung injury induced by PQ poisoning. The role of TNC in this process is closely related to TLR4 and TGF-β signaling pathways.