Studies the consequences of thymosin β4 depletion in human LX-2 hepatic stellate cells (HSCs). Contrary to what might be expected, TB4 depletion (siRNA) paradoxically promoted HSC proliferation, migration, and activation—suggesting TB4 has a restraining role in HSC biology. Serum TB4 and liver tissue TB4 were also characterized across fibrosis stages. Contributes to the paradox later resolved by conditional HSC-specific TB4 KO (PMID 37371128): TB4 expressed in HSCs restrains some activation signals, but in the complex in vivo liver context, HSC-derived TB4 actually promotes fibrosis, highlighting cell context-dependence of TB4's functions.
Abstract
BACKGROUND & AIMS: It has recently been reported that thymosin beta-4 (Tβ4) has anti-fibrogenic effects in human hepatic stellate cells (HSCs) in vitro, but the mechanisms underlying these effects remain unclear. The aim of this study was to investigate the roles of Tβ4 in the proliferation, migration, and activation of HSCs.
METHODS: Enzyme-linked immunosorbent assays (ELISA), immunohistochemistry, and western blot assays were utilized to determine the expression levels of Tβ4 in serum, liver tissues, and LX-2 cells. Tβ4 was depleted in LX-2 cells using small interfering RNAs (siRNAs). Cell proliferation was analyzed using cell counting kit-8 (CCK-8) viability assays, and cell migration was investigated using wound-healing and transwell migration assays.
RESULTS: The expression of Tβ4 was significantly reduced during the progression of liver fibrosis. The depletion of Tβ4 significantly promoted the proliferation and migration of LX-2 cells via the activation of the PI3K/Akt signaling pathway. The pro-migratory and pro-proliferative effects of Tβ4 depletion in LX-2 cells can be counteracted by treatment with the Akt inhibitor MK-2206. In addition, Tβ4 depletion was also associated with the activation of HSCs via the enhanced expression of α-smooth muscle actin (α-SMA) and vimentin.
CONCLUSIONS: Our results suggest that Tβ4 participates in liver fibrosis by inhibiting the migration, proliferation, and activation of HSCs and that Tβ4 may be an effective target in the treatment of liver fibrosis.