Stanniocalcin-1 inhibits thrombin-induced signaling and protects from bleomycin-induced lung injury

Targeting hepatic oxidative stress rescues bone loss in liver fibrosis

OBJECTIVE

Chronic liver diseases often involve metabolic damage to the skeletal system. The underlying mechanism of bone loss in chronic liver diseases remains unclear, and appropriate therapeutic options, except for orthotopic liver transplantation, have proved insufficient for these patients. This study aimed to investigate the efficacy and mechanism of transplantation of immature hepatocyte-like cells converted from stem cells from human exfoliated deciduous teeth (SHED-Heps) in bone loss of chronic liver fibrosis.

METHODS

Mice that were chronically treated with CCl₄ received SHED-Heps, and trabecular bone density, reactive oxygen species (ROS), and osteoclast activity were subsequently analyzed in vivo and in vitro. The effects of stanniocalcin 1 (STC1) knockdown in SHED-Heps were also evaluated in chronically CCl₄ treated mice.

RESULTS

SHED-Hep transplantation (SHED-HepTx) improved trabecular bone loss and liver fibrosis in chronic CCl₄-treated mice. SHED-HepTx reduced hepatic ROS production and interleukin 17 (Il-17) expression under chronic CCl₄ damage. SHED-HepTx reduced the expression of both Il-17 and tumor necrosis factor receptor superfamily 11A (Tnfrsf11a) and ameliorated the imbalance of osteoclast and osteoblast activities in the bone marrow of CCl₄-treated mice. Functional knockdown of STC1 in SHED-Heps attenuated the benefit of SHED-HepTx including anti-bone loss effect by suppressing osteoclast differentiation through TNFSF11-TNFRSF11A signaling and enhancing osteoblast differentiation in the bone marrow, as well as anti-fibrotic and anti-ROS effects in the CCl₄-injured livers.

CONCLUSIONS

These findings suggest that targeting hepatic ROS provides a novel approach to treat bone loss resulting from chronic liver diseases.

Intravitreal Administration of Stanniocalcin-1 Rescues Photoreceptor Degeneration with Reduced Oxidative Stress and Inflammation in a Porcine Model of Retinitis Pigmentosa

PURPOSE

To investigate the effect of stanniocalcin-1 (STC-1), a secreted polypeptide exhibiting multiple functions in cell survival and death, on photoreceptor degeneration in a porcine model of retinitis pigmentosa (RP).

METHODS

P23H transgenic pigs (TG P23H) and wild-type hybrid littermates were obtained from the National Swine Resource and Research Center. Human recombinant STC-1 was injected intravitreally every 2 weeks from postnatal day 15 (P15) to P75. The contralateral eye was injected with balanced salt solution as a control. Electroretinography (ERG) and spectral domain optical coherence tomography (SD-OCT) were performed to evaluate retinal function and morphology in vivo at P90. Retinal tissue was collected for histologic analysis and molecular assays to evaluate the antioxidative and anti-inflammatory mechanisms by which STC-1 may rescue photoreceptor degeneration.

RESULTS

Intravitreal injection of STC-1 improved retinal function in TG P23H pigs with increased photopic and flicker ERG a- and b-wave amplitudes. Greater integrity of the ellipsoid zone (EZ) band on SD-OCT and morphologic rescue with preservation of cone photoreceptors were observed in STC-1-treated TG P23H pigs. STC-1 altered gene expression in TG P23H pig retina on microarray analysis and increased photoreceptor specific gene expression by reverse transcription-polymerase chain reaction analysis. STC-1 significantly decreased oxidative stress and the expressions of NLRP3 inflammasome, cleaved caspase-1, and IL-1β in TG P23H pig retina.

CONCLUSIONS

Intravitreal administration of STC-1 enhances cone photoreceptor function, improves EZ integrity, and reduces retinal degeneration through antioxidative and anti-inflammatory effects in a large animal (pig) model of the most common form of autosomal dominant RP in the United States.

Disrupting biological sensors of force promotes tissue regeneration in large organisms

Tissue repair and healing remain among the most complicated processes that occur during postnatal life. Humans and other large organisms heal by forming fibrotic scar tissue with diminished function, while smaller organisms respond with scarless tissue regeneration and functional restoration. Well-established scaling principles reveal that organism size exponentially correlates with peak tissue forces during movement, and evolutionary responses have compensated by strengthening organ-level mechanical properties. How these adaptations may affect tissue injury has not been previously examined in large animals and humans. Here, we show that blocking mechanotransduction signaling through the focal adhesion kinase pathway in large animals significantly accelerates wound healing and enhances regeneration of skin with secondary structures such as hair follicles. In human cells, we demonstrate that mechanical forces shift fibroblasts toward pro-fibrotic phenotypes driven by ERK-YAP activation, leading to myofibroblast differentiation and excessive collagen production. Disruption of mechanical signaling specifically abrogates these responses and instead promotes regenerative fibroblast clusters characterized by AKT-EGR1.

Humans and other large mammals heal wounds by forming fibrotic scar tissue with diminished function. Here, the authors show that disrupting mechanotransduction through the focal adhesion kinase pathway in large animals accelerates healing, prevents fibrosis, and enhances skin regeneration.

Stanniocalcin-1 Protected Astrocytes from Hypoxic Damage Through the AMPK Pathway

Our previous studies revealed that the expression of stanniocalcin-1 (STC1) in astrocytes increased under hypoxic conditions. However, the role of STC1 in hypoxic astrocytes is not well understood. In this work, we first showed the increased expression of STC1 in astrocyte cell line and astrocytes in the brain tissues of mice after exposure to hypoxia. Then, we found that knockdown of STC1 inhibited cell viability and increased apoptosis. These effects were mediated by decreasing the levels of SIRT3, UCP2, and glycolytic genes and increasing the levels of ROS. Further studies suggested that STC1 silencing promoted oxidative stress and suppressed glycolysis by downregulating AMPKα1. Moreover, HIF-1α knockdown in hypoxic astrocytes led to decreased expression of STC1 and AMPKα1, indicating that the expression of STC1 was regulated by HIF-1α. In conclusion, our study showed that HIF-1α-induced STC1 could protect astrocytes from hypoxic damage by regulating glycolysis and redox homeostasis in an AMPKα1-dependent manner.

STC1 ameliorates cognitive impairment and neuroinflammation of Alzheimer's disease mice via inhibition of ERK1/2 pathway

OBJECTIVE

To investigate the regulatory role of STC1 (Stanniocalcin-1) mediated ERK1/2 pathway in cognitive impairment and neuroinflammation of Alzheimer's disease (AD).

METHODS

WT mice and STC1 Tg mice (transgenic overexpression of STC1) were used to establish AD models to perform behavioral test by Morris water maze. Hippocampal cell apoptosis was quantified by TUNEL staining, the levels of inflammatory cytokines in serum and hippocampal tissues determined by ELISA, as well as oxidative stress-related factors detected by corresponding testing kits, and protein expression of STC1 and ERK1/2 pathway measured by Western blotting.

RESULTS

Compared with WT Sham group, WT AD mice had prolonged escape latency, decreased crossing platform times, increased hippocampal cell apoptosis with up-regulated inflammatory cytokines and oxidative stress-related factors, as well as increased STC1 and ERK1/2 pathway-related molecules. By contrast, STC1 Tg AD mice showed shortened escape latency, increased crossing platform times than WT AD mice, and they also exhibited the decreased apoptosis index and inflammatory cytokines, alleviated oxidative stress-injury, down-regulated protein expression of ERK1/2 pathway, and up-regulated the protein expression of STC1 and UCP2.

CONCLUSION

STC1 overexpression could alleviate oxidative stress-induced injury, reduce neuroinflammation, improve cognitive function to play a neuro-protective role by inhibiting ERK1/2 signaling pathway.

Stanniocalcin 1 Inhibits the Inflammatory Response in Microglia and Protects Against Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy is a serious consequence of sepsis, triggered by the host response against an infectious agent, that can lead to brain damage and cognitive impairment. Several mechanisms have been proposed in this bidirectional communication between the immune system and the brain after sepsis as neuroinflammation, oxidative stress, and mitochondrial dysfunction. Stanniocalcin-1 (STC-1), an endogen neuroprotective protein, acts as an anti-inflammatory and suppresses superoxide generation through induction of uncoupling proteins (UCPs) in the mitochondria. Here, we demonstrated a protective role of STC-1 on inflammatory responses in vitro, in activated microglia stimulated with LPS, and on neuroinflammation, oxidative stress, and mitochondrial function in the hippocampus of rats subjected to an animal model of sepsis by cecal ligation and puncture (CLP), as well the consequences on long-term memory. Recombinant human STC-1 (rhSTC1) suppressed the pro-inflammatory cytokine production in LPS-stimulated microglia without changing the UCP-2 expression. Besides, rhSTC1 injected into the cisterna magna decreased acute hippocampal inflammation and oxidative stress and increased the activity of complex I and II activity of mitochondrial respiratory chain and creatine kinase at 24 h after sepsis. rhSTC1 was effective in preventing long-term cognitive impairment after CLP. In conclusion, rhSTC1 confers significant neuroprotection by inhibiting the inflammatory response in microglia and protecting against sepsis-associated encephalopathy in rats.

Arrestin domain containing 3 promotes Helicobacter pylori-associated gastritis by regulating protease-activated receptor 1

Arrestin domain containing 3 (ARRDC3) represents a newly discovered α-arrestin involved in obesity, inflammation, and cancer. Here, we demonstrate a proinflammation role of ARRDC3 in Helicobacter pylori–associated gastritis. Increased ARRDC3 was detected in gastric mucosa of patients and mice infected with H. pylori. ARRDC3 in gastric epithelial cells (GECs) was induced by H. pylori, regulated by ERK and PI3K-AKT pathways in a cagA-dependent manner. Human gastric ARRDC3 correlated with the severity of gastritis, and mouse ARRDC3 from non-BM–derived cells promoted gastric inflammation. This inflammation was characterized by the CXCR2-dependent influx of CD45⁺CD11b⁺Ly6C^–Ly6G⁺ neutrophils, whose migration was induced via the ARRDC3-dependent production of CXCL2 by GECs. Importantly, gastric inflammation was attenuated in Arrdc3^–/– mice but increased in protease-activated receptor 1^–/– (Par1^–/–) mice. Mechanistically, ARRDC3 in GECs directly interacted with PAR1 and negatively regulated PAR1 via ARRDC3-mediated lysosomal degradation, which abrogated the suppression of CXCL2 production and following neutrophil chemotaxis by PAR1, thereby contributing to the development of H. pylori–associated gastritis. This study identifies a regulatory network involving H. pylori, GECs, ARRDC3, PAR1, and neutrophils, which collectively exert a proinflammatory effect within the gastric microenvironment. Efforts to inhibit this ARRDC3-dependent pathway may provide valuable strategies in treating of H. pylori–associated gastritis.

A regulatory network including H. pylori, GECs, ARRDC3, PAR1, and neutrophils collectively exerts a pro-inflammatory effect within the gastric microenvironment.

Therapeutic Potential of “Exosomes Derived Multiple Allogeneic Proteins Paracrine Signaling: Exosomes d-MAPPS” is Based on the Effects of Exosomes, Immunosuppressive and Trophic Factors

Due to their differentiation capacity and potent immunosuppressive and pro-angiogenic properties, mesenchymal stem cells (MSCs) have been considered as new therapeutic agents in regenerative medicine. Since most of MSC-mediated beneficent effects are a consequence of their paracrine action, we designed MSC-based product “Exosomes Derived Multiple Allogeneic Proteins Paracrine Signaling (Exosomes d-MAPPS), which activity is based on MSCs-derived growth factors and immunomodulatory cytokines capable to attenuate inflammation and to promote regeneration of injured tissues. Interleukin 1 receptor antagonist (IL-1Ra) and IL-27 were found in high concentrations in Exosomes d-MAPPS samples indicating strong anti-inflammatory and immunosuppressive potential of Exosomes d-MAPPS. Additionally, high concentrations of vascular endothelial growth factor receptor (VEGFR1) and chemokines (CXCL16, CCL21, CXCL14) were noticed at Exosomes d-MAPPS samples suggesting their potential to promote generation of new blood vessels and migration of CXCR6, CCR7 and CXCR4 expressing cells. Since all proteins which were found in high concentration in Exosomes d-MAPPS samples (IL-1Ra, CXCL16, CXCL14, CCL21, IL-27 and VEGFR1) are involved in modulation of lung, eye, and synovial inflammation, Exosomes d-MAPPS samples were prepared as inhalation and ophthalmic solutions in addition to injection formulations; their application in several patients suffering from chronic obstructive pulmonary disease, osteoarthritis, and dry eye syndrome resulted with significant improvement of biochemical and functional parameters. In conclusion, Exosomes d-MAPPS, due to the presence of important anti-inflammatory, immunomodulatory, and pro-angiogenic factors, represents potentially new therapeutic agent in regenerative medicine that should be further tested in large clinical studies.

Megalin mediates plasma membrane to mitochondria cross-talk and regulates mitochondrial metabolism

Mitochondrial intracrines are extracellular signaling proteins, targeted to the mitochondria. The pathway for mitochondrial targeting of mitochondrial intracrines and actions in the mitochondria remains unknown. Megalin/LRP2 mediates the uptake of vitamins and proteins, and is critical for clearance of amyloid-β protein from the brain. Megalin mutations underlie the pathogenesis of Donnai-Barrow and Lowe syndromes, characterized by brain defects and kidney dysfunction; megalin was not previously known to reside in the mitochondria. Here, we show megalin is present in the mitochondria and associates with mitochondrial anti-oxidant proteins SIRT3 and stanniocalcin-1 (STC1). Megalin shuttles extracellularly-applied STC1, angiotensin II and TGF-β to the mitochondria through the retrograde early endosome-to-Golgi transport pathway and Rab32. Megalin knockout in cultured cells impairs glycolytic and respiratory capacities. Thus, megalin is critical for mitochondrial biology; mitochondrial intracrine signaling is a continuum of the retrograde early endosome-to-Golgi-Rab32 pathway and defects in this pathway may underlie disease processes in many systems.

The Role of Autophagy and the Chemokine (C-X-C Motif) Ligand 16 During Acute Lung Injury in Mice

Background

Acute lung injury (ALI) is responsible for mortality in hospitalized patients. Autophagy can negatively regulate inflammatory response, and CXCL16 (chemokine (C-X-C motif) ligand 16) is a kind of chemokine, which is closely related to the inflammatory response. However, the relationship between autophagy and CXCL16 in ALI is still unclear. This study aimed to investigate the role of autophagy and chemokine CXCL16 in ALI in mice.

Material/Methods

Thirty-two male C57BL/6 mice were divided into four groups. The control group (C group) was given normal saline through intraperitoneal injection. The L group was given LPS (lipopolysaccharide) at 30 mg/kg to construct an ALI model. The 3-MA group received an intraperitoneal injection of inhibitor of autophagy 3-methyladenine at 15 mg/kg, 30 minutes before LPS injection. The anti-CXCL16 group was given 20 mg/kg of CXCL16 monoclonal antibody 30 minutes before the LPS injection.

Results

In the 3-MA Group, the level of histological analysis, lung wet/dry ratio, total protein of BAL (bronchoalveolar lavage fluid) and TNF-α level were higher than the L group (p<0.05), the level of autophagy was lower than the L group (p<0.05), and the level of CXCL16 was higher than the L group (p<0.05). In the anti-CXCL16 group, the level of histological analysis, lung wet/dry ratio, BAL protein, and TNF-α level were declined compared to the L group (p<0.05), but there was no statistically significant difference in expression of CXCL16 detected by ELISA between the anti-CXCL16 group and the L group (p>0.05).

Conclusions

Autophagy played a protective role in ALI induced by LPS in mice. Autophagy could regulate the level of CXCL16. The chemokine CXCL16 could exacerbate ALI.

Long-term photoreceptor rescue in two rodent models of retinitis pigmentosa by adeno-associated virus delivery of Stanniocalcin-1

Retinal degenerations, including age-related macular degeneration and the retinitis pigmentosa family of diseases, are among the leading causes of legal blindness in the United States. We previously found that Stanniocalcin-1 (STC-1) reduced photoreceptor loss in the S334ter-3 and Royal College of Surgeons rat models of retinal degeneration. The results were attributed in part to a reduction in oxidative stress. Herein, we tested the hypothesis that long-term delivery of STC-1 would provide therapeutic rescue in more chronic models of retinal degeneration. To achieve sustained delivery, we produced an adeno-associated virus (AAV) construct to express STC-1 (AAV-STC-1) under the control of a retinal ganglion cell targeting promoter human synapsin 1 (hSYN1). AAV-STC-1 was injected intravitreally into the P23H-1 and S334ter-4 rhodopsin transgenic rats at postnatal day 10. Tissues were collected at postnatal day 120 for confirmation of STC-1 overexpression and histologic and molecular analysis. Electroretinography (ERG) was performed in a cohort of animals at that time. Overexpression of STC-1 resulted in a significant preservation of photoreceptors as assessed by outer nuclear thickness in the P23H-1 (P < 0.05) and the S334ter-4 (P < 0.005) models compared to controls. Additionally, retinal function was significantly improved in the P23H-1 model with overexpressed STC-1 as assessed by ERG analysis (scotopic b-wave P < 0.005 and photopic b-wave P < 0.05). Microarray analysis identified common downstream gene expression changes that occurred in both models. Genes of interest based on their function were selected for validation by quantitative real-time PCR and were significantly increased in the S334ter-4 model.

Stanniocalcin-1 attenuates ischemic cardiac injury and response of differentiating monocytes/macrophages to inflammatory stimuli

Stanniocalcin-1 (STC-1) is a multifunctional glycoprotein with antioxidant and anti-inflammatory properties. Ischemic myocardial necrosis generates "danger" signals that perpetuate detrimental inflammatory reactions often involving monocyte recruitment and their subsequent differentiation into proinflammatory macrophages. Therefore, we evaluated the effects of recombinant STC-1 (rSTC-1) on monocyte phenotype and in a mouse model of myocardial infarction. Using an established protocol to differentiate human monocytes into macrophages, we demonstrated that rSTC-1 did not alter morphology of the differentiated cells, toll-like receptor (TLR) 4 expression, or expression of the myeloid cell marker CD11b. However, rSTC-1 treatment before differentiation attenuated the rise in the expression of CD14, a TLR4 coreceptor and pathogen sensor that propagates innate immune responses, and suppressed levels of inflammatory cytokines produced by the differentiated cells in response to the CD14-TLR4 ligand lipopolysaccharide. Moreover, rSTC-1 treatment reduced CD14 expression in monocytes stimulated with endogenous danger signals. Interestingly, the effects of rSTC-1 on CD14 expression were not reproduced by a superoxide dismutase mimetic. In mice with induced myocardial infarcts, intravenous administration of rSTC-1 decreased CD14 expression in the heart as well as levels of tumor necrosis factor alpha, C-X-C motif ligand 2, interleukin 1 beta, and myeloperoxidase. It also suppressed the formation of scar tissue while enhancing cardiac function. The data suggests that one of the beneficial effects of STC-1 might be attributed to suppression of CD14 on recruited monocytes and macrophages that limits their inflammatory response. STC-1 may be a promising therapy to protect the heart and other tissues from ischemic injury.