Molecular mechanisms of splenectomy-induced hepatocyte proliferation

PLoS One. 2020 Jun 12;15(6):e0233767. doi: 10.1371/journal.pone.0233767. eCollection 2020.

Abstract

Functional and anatomical connection between the liver and the spleen is most clearly manifested in various pathological conditions of the liver (cirrhosis, hepatitis). The mechanisms of the interaction between the two organs are still poorly understood, as there have been practically no studies on the influence exerted by the spleen on the normal liver. Mature male Sprague-Dawley rats of 250-260 g body weight, 3 months old, were splenectomized. The highest numbers of Ki67+ hepatocytes in the liver of splenectomized rats were observed at 24 h after the surgery, simultaneously with the highest index of Ki67-positive hepatocytes. After surgical removal of the spleen, expression of certain genes in the liver tissues increased. A number of genes were upregulated in the liver at a single time point of 24 h, including Ccne1, Egf, Tnfa, Il6, Hgf, Met, Tgfb1r2 and Nos2. The expression of Ccnd1, Tgfb1, Tgfb1r1 and Il10 in the liver was upregulated over the course of 3 days after splenectomy. Monitoring of the liver macrophage populations in splenectomized animals revealed a statistically significant increase in the proportion of CD68-positive cells in the liver (as compared with sham-operated controls) detectable at 24 h and 48 h after the surgery. The difference in the liver content of CD68-positive cells between splenectomized and sham-operated animals evened out by day 3 after the surgery. No alterations in the liver content of CD163-positive cells were observed in the experiments. A decrease in the proportion of CD206-positive liver macrophages was observed at 48 h after splenectomy. The splenectomy-induced hepatocyte proliferation is described by us for the first time. Mechanistically, the effect is apparently induced by the removal of spleen as a major source of Tgfb1 (hepatocyte growth inhibitor) and subsequently supported by activation of proliferation factor-encoding genes in the liver.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Proliferation*
  • Hepatocytes / metabolism*
  • Hepatocytes / physiology
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism
  • Macrophages / metabolism
  • Macrophages / physiology
  • Male
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Splenectomy / adverse effects*
  • Transcriptome
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism

Substances

  • Interleukin-6
  • Transforming Growth Factor beta
  • Nitric Oxide Synthase Type II
  • Nos2 protein, rat

Grants and funding

The work of AVE, TKF, PAV, MPN, AVL, AVM, IVA, EYK was supported by the Russian Science Foundation (https://rscf.ru/en/, grant number 17-15-01419). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.