HMGB1-induced activation of ER stress contributes to pulmonary artery hypertension in vitro and in vivo.

BACKGROUND: HMGB1 and ER stress have been considered to participate in the progression of pulmonary artery hypertension (PAH). However, the molecular mechanism underlying HMGB1 and ER stress in PAH remains unclear. This study aims to explore whether HMGB1 induces pulmonary artery smooth muscle cells (PASMCs) functions and pulmonary artery remodeling through ER stress activation. METHODS: Primary cultured PASMCs and monocrotaline (MCT)-induced PAH rats were applied in this study. Cell proliferation and migration were determined by CCK-8, EdU and transwell assay. Western blotting was conducted to detect the protein levels of protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor-4 (ATF4), seven in absentia homolog 2 (SIAH2) and homeodomain interacting protein kinase 2 (HIPK2). Hemodynamic measurements, immunohistochemistry staining, hematoxylin and eosin staining were used to evaluate the development of PAH. The ultrastructure of ER was observed by transmission electron microscopy. RESULTS: In primary cultured PASMCs, HMGB1 reduced HIPK2 expression through upregulation of ER stress-related proteins (PERK and ATF4) and subsequently increased SIAH2 expression, which ultimately led to PASMC proliferation and migration. In MCT-induced PAH rats, interfering with HMGB1 by glycyrrhizin, suppression of ER stress by 4-phenylbutyric acid or targeting SIAH2 by vitamin K3 attenuated the development of PAH. Additionally, tetramethylpyrazine (TMP), as a component of traditional Chinese herbal medicine, reversed hemodynamic deterioration and vascular remodeling by targeting PERK/ATF4/SIAH2/HIPK2 axis. CONCLUSIONS: The present study provides a novel insight to understand the pathogenesis of PAH and suggests that targeting HMGB1/PERK/ATF4/SIAH2/HIPK2 cascade might have potential therapeutic value for the prevention and treatment of PAH.

Expression, purification and identification of Pla a1 in a codon-optimized Platanus pollen allergen.

The present study aimed to express, purify and identify the major allergen gene, Pla a1, in Platanus pollen. According to previous studies, the major gene sequences of the Pla a1 allergen were obtained and codon optimization and synthesis of the genome were performed using DNAStar software. Following binding of the target gene fragment and the pET-44a vector, the JM109 cells were transfected to produce positive clones. The vectors were then transformed into Escherichia coli Rosetta cells to induce the expression of the target protein. The exogenous protein was purified using affinity chromatography and was identified by western blot analysis. Pla a1, the major allergen protein in Platanus pollen, was successfully isolated and this exogenous protein was purified using affinity chromatography. The present study was the first, to the best of our knowledge, to obtain expression of the allergen recombinant protein, Pla a1, fused with a Strep-TagII via codon optimization and provided the basis for the preparation of allergens with high purity, recombinant hypoallergenic allergens and allergen nucleic acid vaccines.

[Immunological characteristics of the recombinant major pollen allergen pTSX2 of Humulus scandens].

OBJECTIVE: To identify the immunological characteristics of the recombinant major pollen allergen pTSX2 of Humulus scandens and evaluate its safety in immunotherapy of allergic asthma in mice. METHODS: Western blotting was used to characterize the immunological properties of pTSX2, and its immunogenicity in normal mice was evaluated by detecting sIgG and sIgE levels. The mouse models of allergic asthma were immunized with pTSX2 and examined for sIgE and sIgG levels, total cells and eosinophils percentage in BALF, interleukin-4 (IL-4) and interferon-γ (IFN-γ) levels in BALF and spleen homogenate, and changes in lung pathologies. RESULTS: Western blotting showed that pTSX2 reacted with the majority (about 70%) of sera from patients allergic to Humulus pollen. In normal mice, pTSX2 mainly induced the production of sIgG. In mouse models of allergic asthma, intervention with pTSX2 caused a significant reduction of sIgE and an increase of sIgG (P<0.05), significantly decreased the total cells and eosinophils in BALF (P<0.05), obviously lowered IL-4 but increased IFN-γ in BALF and spleen homogenate (P<0.05), and diminished inflammatory cell infiltration and percentage of eosinophils in the lung tissues. CONCLUSIONS: pTSX2 shows a definite therapeutic effect and safety in the treatment of allergic asthma in mice possibly by inhibiting sIgE and inducing sIgG production, suppressing airway allergic inflammation and regulating the balance between Thl and Th2.