Role of haematopoietic cell‐specific protein 1‐associated protein X‐1 gene in lipopolysaccharide‐induced apoptosis of human dermal fibroblasts

Abstract

Wound healing may be disrupted by lipopolysaccharide (LPS)‐induced mitochondrial dysfunction, inflammation, and excessive oxidative stress, which can lead to undesirable consequences. The haematopoietic cell‐specific protein 1‐associated protein X‐1 (HAX‐1) is a mitochondrial matrix protein that regulates mitochondrial function. This study aimed to comprehensively identify the role of HAX‐1 in the inhibition of LPS‐induced mitochondrial dysfunction and apoptosis in human dermal fibroblasts (HDFs). HAX‐1 expression was assessed in the HDF‐a cell line using real‐time polymerase chain reaction, western blotting, and immunohistochemical staining. The viability, migration, and apoptosis of HDF‐a cells were evaluated using the water‐soluble tetrazolium‐1 assay, transwell assay, and flow cytometry analysis, respectively. Mitochondrial function was evaluated based on reactive oxygen species (ROS) generation and mitochondrial membrane potential (ΔΨm). Our results demonstrated that LPS stimulation markedly repressed HAX‐1 expression in HDFs and silencing of HAX‐1 led to mitochondrial ROS accumulation, ΔΨm disruption, and abnormal mitochondrial morphology. Accordingly, overexpression of HAX‐1 or administration of metformin enhanced mitochondrial fusion and normalized mitochondrial dynamics, thereby reversing LPS‐induced mitochondrial dysfunction, fibroblast apoptosis, and viability and migration inhibition in HDF‐a cells. These data support a mechanism wherein HAX‐1 plays a crucial role in LPS‐induced fibroblast apoptosis in a mitochondria‐dependent manner.

Dermal Fibroblast Migration and Proliferation Upon Wounding or Lipopolysaccharide Exposure is Mediated by Stathmin

“…crucial initial factor in wound healing (Ninan et al, 2015;Visan, 2019) and fibroblasts are deemed to play an essential role in this process (Desjardins-Park et al, 2018;Visan, 2019), the relationship and mechanisms between fibroblasts and LPS exposure remain less well defined. In our present study, we used LPS (500 ng/ml, 24 h) to mimic inflammatory stimulation in vitro during wound healing with a superimposed infection, because appropriate LPS stimulation could activate inflammatory response and start wound healing (Landén et al, 2016;Li et al, 2017), whereas inappropriate dose or treatment time of LPS may not promote wound healing, or even delay wound healing due to excessive oxidative stress or severe infection (Ning et al, 2021). We found that LPS induced elevated stathmin expression and promoted HDF migration and proliferation.…”