Hepatocyte HSPA12A inhibits macrophage chemotaxis and activation to attenuate liver ischemia/reperfusion injury via suppressing glycolysis-mediated HMGB1 lactylation and secretion of hepatocytes.

Rationale: Liver ischemia-reperfusion (LI/R) injury is characterized by two interconnected phases: local ischemia that causes hepatic cell damage to release damage-associated molecular pattern (DAMPs), and DAMPs that recruit immune cells to elicit inflammatory cascade for further injury of hepatocytes. High-mobility group box 1 (HMGB1) is a representative DAMP. Studies in macrophages demonstrated that HMGB1 is secreted after lactylation during sepsis. However, whether lactylation mediates HMGB1 secretion from hepatocytes after LI/R is known. Heat shock protein A12A (HSPA12A) is an atypical member of HSP70 family. Methods: Gene expression was examined by microarray analysis and immunoblotting. The hepatic injury was analyzed using released ALT and AST activities assays. Hepatic macrophage chemotaxis was evaluated by Transwell chemotaxis assays. Inflammatory mediators were evaluated by immunoblotting. HMGB1 secretion was examined in exosomes or serum. HMGB1 lactylation was determined using immunoprecipitation and immunoblotting. Results: Here, we report that LI/R decreased HSPA12A expression in hepatocytes, while hepatocyte-specific HSPA12A overexpression attenuated LI/R-induced hepatic dysfunction and mortality of mice. We also noticed that hepatocyte HSPA12A overexpression suppressed macrophage chemotaxis to LI/R-exposed livers in vivo and to hypoxia/reoxygenation (H/R)-exposed hepatocytes in vitro. The LI/R-increased serum HMGB1 levels of mice and the H/R-increased HMGB1 lactylation and secretion levels of hepatocytes were also inhibited by hepatocyte HSPA12A overexpression. By contrast, HSPA12A knockout in hepatocytes promoted not only H/R-induced HMGB1 lactylation and secretion of hepatocytes but also the effects of H/R-hepatocytes on macrophage chemotaxis and inflammatory activation, while all these deleterious effects of HSPA12A knockout were reversed following hepatocyte HMGB1 knockdown. Further molecular analyses showed that HSPA12A overexpression reduced glycolysis-generated lactate, thus decreasing HMGB1 lactylation and secretion from hepatocytes, thereby inhibiting not only macrophage chemotaxis but also the subsequent inflammatory cascade, which ultimately protecting against LI/R injury. Conclusion: Taken together, these findings suggest that hepatocyte HSPA12A is a novel regulator that protects livers from LI/R injury by suppressing glycolysis-mediated HMGB1 lactylation and secretion from hepatocytes to inhibit macrophage chemotaxis and inflammatory activation. Therefore, targeting hepatocyte HSPA12A may have therapeutic potential in the management of LI/R injury in patients.

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.

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

Liver dysfunction is strongly associated with poor survival of sepsis patients. Cytosolic lipopolysaccharide (LPS) sensing by Caspase-4/5/11 for pyroptosis activation is a major driver of the development of sepsis. Studies in macrophages and endothelial cells have demonstrated that LPS is inactivated by acyloxyacyl hydrolase (AOAH) and leading to desensitizing Caspase-4/5/11 to LPS. However, little is known about the cytosolic LPS-induced pyroptosis in hepatocytes during sepsis. Heat shock protein 12A (HSPA12A) is a novel member of the HSP70 family. Here, we report that LPS increased HSPA12A nuclear translocation in hepatocytes, while knockout of HSPA12A (Hspa12a-/-) in mice promoted LPS-induced acute liver injury. We also noticed that the LPS-induced Caspase-11 activation and its cleavage of gasdermin D (GSDMD) to produce the membrane pore-forming GSDMDNterm (markers of pyroptosis) were greater in livers of Hspa12a-/- mice compared with its wild type controls. Loss- and gain-of-function studies showed that HSPA12A deficiency promoted, whereas HSPA12A overexpression inhibited, cytosolic LPS accumulation, Caspase-11 activation and GSDMDNterm generation in primary hepatocytes following LPS incubation. Notably, LPS-induced AOAH expression was suppressed by HSPA12A deficiency, whereas AOAH overexpression reversed the HSPA12A deficiency-induced promotion of LPS-evoked and Caspase-11-mediated pyroptosis of hepatocytes. In-depth molecular analysis showed that HSPA12A interacted directly with peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and increased its nuclear translocation, thereby inducing AOAH expression for cytosolic LPS inactivation, which ultimately leading to inhibition of the Caspase-11 mediated pyroptosis of hepatocytes. Taken together, these findings revealed HSPA12A as a novel player against LPS-induced liver injury by inhibiting cytosolic LPS-induced hepatocyte pyroptosis via PGC-1α-mediated AOAH expression. Therefore, targeting hepatocyte HSPA12A represents a viable strategy for the management of liver injury in sepsis patients.

Cardiomyocyte-specific deficiency of HSPB1 worsens cardiac dysfunction by activating NFκB-mediated leucocyte recruitment after myocardial infarction.

Aims: Inadequate healing after myocardial infarction (MI) leads to heart failure and fatal ventricular rupture, while optimal healing requires timely induction and resolution of inflammation. This study tested the hypothesis that heat shock protein B1 (HSPB1), which limits myocardial inflammation during endotoxemia, modulates wound healing after MI. Methods and results: To test this hypothesis, cardiomyocyte-specific HSPB1 knockout (Hspb1-/-) mice were generated using the Cre-LoxP recombination system. MI was induced by ligation of the left anterior descending coronary artery in Hspb1-/- and wild-type (WT) littermates. HSPB1 was up-regulated in cardiomyocytes of WT animals in response to MI, and deficiency of cardiomyocyte HSPB1 increased MI-induced cardiac rupture and mortality within 21 days after MI. Serial echocardiography showed more aggravated remodelling and cardiac dysfunction in Hspb1-/- mice than in WT mice at 1, 3, and 7 days after MI. Decreased collagen deposition and angiogenesis, as well as increased MMP2 and MMP9 activity, were also observed in Hspb1-/- mice compared with WT controls after MI, using immunofluorescence, polarized light microscopy, and zymographic analyses. Notably, Hspb1-/- hearts exhibited enhanced and prolonged leucocyte infiltration, enhanced expression of inflammatory cytokines, and enhanced TLR4/MyD88/NFκB activation compared with WT controls after MI. In-depth molecular analyses in both mice and primary cardiomyocytes demonstrated that cardiomyocyte-specific knockout of HSPB1 increased nuclear factor-κB (NFκB) activation, which promoted the expression of proinflammatory mediators. This led to increased leucocyte recruitment, thereby to excessive inflammation, ultimately resulting in adverse remodelling, cardiac dysfunction, and cardiac rupture following MI. Conclusion: These data suggest that HSPB1 acts as a negative regulator of NFκB-mediated leucocyte recruitment and the subsequent inflammation in cardiomyocytes. Cardiomyocyte HSPB1 is required for wound healing after MI and could be a target for myocardial repair in MI patients.

Gold mesostructures with tailored surface topography and their self-assembly arrays for surface-enhanced Raman spectroscopy.

We report a facile particle mediated aggregation protocol to synthesize "sea urchin"-like gold mesoparticles with tailored surface topography via a secondary nucleation and growth process. Surprisingly, these multitip Au mesoparticles are capable of self-assembling into monolayer or multiple layer arrays on Si substrates with a convincing reproducibility and homogeneity over large areas. Raman measurements show that these individual sea urchin-like multitipped gold mesoparticles exhibit a high enhancement of surface-enhanced Raman scattering (SERS). In addition, the sea urchin-like mesoparticle arrays display a further enhancement of SERS by 1 or 2 orders of magnitude over the individual mesoparticle due to the formation of additional hot spots between the particles. The current protocol stands out as a potentially interesting approach for the fabrication of technologically important SERS-based sensors.

Enhanced light absorption of TiO(2) in the near-ultraviolet band by Au nanoparticles.

We propose a scheme to enhance near-UV band absorption of a rutile TiO(2) nanoparticle by placing Au nanoparticles in its neighborhood. The discrete-dipole approximation method was employed to calculate the absorption spectrum of pure rutile TiO(2) and that of TiO(2) mixed with Au nanoparticles. The results indicate that pure rutile TiO(2) has its maximum absorption located in the deep-UV band. With the existence of Au nanoparticles, a significant light harvesting effect occurs, and this maximum shifts to the near-UV band, where usual excitation wavelength falls.