HSPA12A improves endothelial integrity to attenuate lung injury during endotoxemia through activating ERKs and Akt-dependent signaling.

Acute lung injury (ALI) is a critical manifestation of sepsis/septic shock. Disruption of endothelial barrier function is critical for ALI pathogenesis; however, the regulation of endothelial barrier integrity remains largely unclear. Heat shock protein A12A (HSPA12A) is an atypical member of HSP70 family. We have recently demonstrated that hepatocyte HSPA12A attenuated the bacteria endotoxin (lipopolysaccharide, LPS)-induced liver injury. However, the role of HSPA12A in endothelial barrier function and ALI is unknown. Here in this study, HSPA12A showed upregulation in lungs of mice during bacteria endotoxin (lipopolysaccharide, LPS)-induced lung injury in vivo and in primary human umbilical vein endothelial cells (HUVECs) during LPS-induced barrier disruption in vitro. Knockout of HSPA12A in mice exacerbated LPS-induced ALI. Intriguingly, overexpression of HSPA12A in HUVECs attenuated the LPS-induced endothelial hyperpermeability. In line with this, HSPA12A overexpression increased VE-cadherin and decreased VEGF expression following LPS treatment in HUVECs. Also, knockout of HSPA12A enhanced the LPS-evoked pulmonary endothelial cell apoptosis in mice whereas overexpression of HSPA12A inhibited the LPS-induced death of HUVECs. The levels of ERKs and Akt phosphorylation in HUVECs were promoted by HSPA12A overexpression when cells exposed to LPS. Importantly, inhibition of either ERKs or Akt diminished the HSPA12A-induced protection from LPS-induced endothelial hyperpermeability and death. Taken together, these findings indicated that HSPA12A is a novel regulator of endothelial barrier function through both ERKs and Akt-mediated signaling. HSPA12A might represent a viable strategy for the pulmonary protection against endotoxemia challenge.

Dai Y ，Liu J ，Zhang X ，Min X ，Wu J ，Du S ，Li T ，Liu L ，Ding Z ... -  《-》

HSPA12B attenuates acute lung injury during endotoxemia in mice.

Acute lung injury (ALI) is a critical manifestation of sepsis/septic shock. Heat shock protein A12B (HSPA12B), an endothelial cell-expressed heat shock protein, shows a negative regulation of lipopolysaccharide (LPS)-induced inflammation in myocardium and endothelial cells. However, it is unclear whether HSPA12B exerts protective effects against ALI during sepsis/septic shock. In this study, we treated HSPA12B transgenic mice (Tg) and wild type littermates (WT) with LPS for 6h to induce endotoxemia. LPS treatment significantly caused pulmonary injuries as evidenced by microarchitecture destruction, vascular leakage and neutrophil recruitment in lungs of WT mice. However, the LPS-induced pulmonary injuries were significantly attenuated in Tg mice. Moreover, the LPS-induced activation of extracellular signal-regulated kinases (ERKs) and upregulation of intercellular adhesion molecule-1 (ICAM-1) and Cyclooxygenase-2 (Cox-2) were inhibited in Tg lungs compared with that in WT mice. Additionally, Tg lungs showed a significant lower level of vascular endothelial growth factor (VEGF) compared with WT mice. Our results demonstrate a pulmonary protective effect of HSPA12B against endotoxin challenge, which indicates management of HSPA12B expression could serve as a potential therapeutic target for ALI during sepsis/septic shock.

Zhang X ，Li J ，Li C ，Li Y ，Zhu W ，Zhou H ，Ding Z ，Liu L ... -  《-》

HSPA12A attenuates lipopolysaccharide-induced liver injury through inhibiting caspase-11-mediated hepatocyte pyroptosis via PGC-1α-dependent acyloxyacyl hydrolase expression.

Liu J ，Du S ，Kong Q ，Zhang X ，Jiang S ，Cao X ，Li Y ，Li C ，Chen H ，Ding Z ，Liu L ... -  《-》

Ablation of endothelial Pfkfb3 protects mice from acute lung injury in LPS-induced endotoxemia.

Acute lung injury (ALI) is one of the leading causes of death in sepsis. Endothelial inflammation and dysfunction play a prominent role in development of ALI. Glycolysis is the predominant bioenergetic pathway for endothelial cells (ECs). However, the role of EC glycolysis in ALI of sepsis remains unclear. Here we show that both the expression and activity of PFKFB3, a key glycolytic activator, were markedly increased in lipopolysaccharide (LPS)-treated human pulmonary arterial ECs (HPAECs) in vitro and in lung ECs of mice challenged with LPS in vivo. PFKFB3 knockdown significantly reduced LPS-enhanced glycolysis in HPAECs. Compared with LPS-challenged wild-type mice, endothelial-specific Pfkfb3 knockout (Pfkfb3ΔVEC) mice exhibited reduced endothelium permeability, lower pulmonary edema, and higher survival rate. This was accompanied by decreased expression of intracellular adhesion molecule-1 (Icam-1) and vascular cell adhesion molecule 1 (Vcam-1), as well as decreased neutrophil and macrophage infiltration to the lung. Consistently, PFKFB3 silencing or PFKFB3 inhibition in HPAECs and human pulmonary microvascular ECs (HPMVECs) significantly downregulated LPS-induced expression of ICAM-1 and VCAM-1, and monocyte adhesion to human pulmonary ECs. In contrast, adenovirus-mediated PFKFB3 overexpression upregulated ICAM-1 and VCAM-1 expression in HPAECs. Mechanistically, PFKFB3 silencing suppressed LPS-induced nuclear translocation of nuclear factor κB (NF-κB)-p65, and NF-κB inhibitors abrogated PFKFB3-induced expression of ICAM-1 and VCAM-1. Finally, administration of the PFKFB3 inhibitor 3PO also reduced the inflammatory response of vascular endothelium and protected mice from LPS-induced ALI. Overall, these findings suggest that targeting PFKFB3-mediated EC glycolysis is an efficient therapeutic strategy for ALI in sepsis.

Wang L ，Cao Y ，Gorshkov B ，Zhou Y ，Yang Q ，Xu J ，Ma Q ，Zhang X ，Wang J ，Mao X ，Zeng X ，Su Y ，Verin AD ，Hong M ，Liu Z ，Huo Y ... -  《-》

HSPA12A Stimulates p38/ERK-AP-1 Signaling to Promote Angiogenesis and Is Required for Functional Recovery Postmyocardial Infarction.

Angiogenesis plays a critical role in wound healing postmyocardial infarction (MI). However, there is still a lack of ideal angiogenic therapeutics for rescuing ischemic hearts clinically, suggesting that a more understanding regarding angiogenesis regulation is urgently needed. Heat shock protein A12A (HSPA12A) is an atypical member of the HSP70 family. Here, we demonstrated that HSPA12A was upregulated during endothelial tube formation, a characteristic of in vitro angiogenesis. Intriguingly, overexpression of HSPA12A promoted in vitro angiogenic characteristics including proliferation, migration, and tube formation of endothelial cells. By contrast, deficiency of HSPA12A impaired myocardial angiogenesis and worsened cardiac dysfunction post-MI in mice. The expression of genes related to angiogenesis (VEGF, VEGFR2, and Ang-1) was decreased by HSPA12A deficiency in MI hearts of mice, whereas their expression was increased by HSPA12A overexpression in endothelial cells. HSPA12A overexpression in endothelial cells increased phosphorylation levels and nuclear localization of AP-1, a transcription factor dominating angiogenic gene expression. Also, HSPA12A increased p38 and ERK phosphorylation levels, whereas inhibition of p38 or ERKs diminished the HSPA12A-promoted AP-1 phosphorylation and nuclear localization, as well as VEGF and VEGFR2 expression in endothelial cells. Notably, inhibition of either p38 or ERKs diminished the HSPA12A-promoted in vitro angiogenesis characteristics. The findings identified HSPA12A as a novel angiogenesis activator, and HSPA12A might represent a viable strategy for the management of myocardial healing in patients with ischemic heart diseases.

Li T ，Wu J ，Yu W ，Mao Q ，Cheng H ，Zhang X ，Li Y ，Li C ，Ding Z ，Liu L ... -  《-》