Publications by authors named "Fengchun Liu"

12 Publications

  • Page 1 of 1

Natural killer cells activated through NKG2D mediate lung ischemia-reperfusion injury.

J Clin Invest 2021 Feb;131(3)

Department of Medicine, University of California, San Francisco, California.

Pulmonary ischemia-reperfusion injury (IRI) is a clinical syndrome of acute lung injury that occurs after lung transplantation or remote organ ischemia. IRI causes early mortality and has no effective therapies. While NK cells are innate lymphocytes capable of recognizing injured cells, their roles in acute lung injury are incompletely understood. Here, we demonstrated that NK cells were increased in frequency and cytotoxicity in 2 different IRI mouse models. We showed that NK cells trafficked to the lung tissue from peripheral reservoirs and were more mature within lung tissue. Acute lung ischemia-reperfusion injury was blunted in a NK cell-deficient mouse strain but restored with adoptive transfer of NK cells. Mechanistically, NK cell NKG2D receptor ligands were induced on lung endothelial and epithelial cells following IRI, and antibody-mediated NK cell depletion or NKG2D stress receptor blockade abrogated acute lung injury. In human lung tissue, NK cells were increased at sites of ischemia-reperfusion injury and activated NK cells were increased in prospectively collected human bronchoalveolar lavage in subjects with severe IRI. These data support a causal role for recipient peripheral NK cells in pulmonary IRI via NK cell NKG2D receptor ligation. Therapies targeting NK cells may hold promise in acute lung injury.
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http://dx.doi.org/10.1172/JCI137047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7852842PMC
February 2021

CircHIPK3 Facilitates the G2/M Transition in Prostate Cancer Cells by Sponging miR-338-3p.

Onco Targets Ther 2020 22;13:4545-4558. Epub 2020 May 22.

Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Yuzhong, Chongqing 408000, People's Republic of China.

Background: Circular RNAs (circRNAs) play a crucial role in gene expression regulation. CircHIPK3 is a circRNA derived from Exon 2 of HIPK3 gene and its role in prostate cancer (PCa) is still unclear.

Methods: CCK8 assays, flow cytometry and colony formation assays were performed to assess the effects of circHIPK3 in PCa cells. Bioinformatics analysis, RNA pull-down assay, RNA immunoprecipitation assay (RIP), and luciferase activity assay were performed to dissect the mechanism underlying circHIPK3-mediated G2/M transition in PCa cells.

Results: CircHIPK3 expression was upregulated in PCa cells and prostate cancer tissues. Overexpression of circHIPK3 or circHIPK3 silencing altered PCa viability, proliferation and apoptosis in vitro. CircHIPK3 could sponge miR-338-3p and inhibit its activity, resulting in increased expression of Cdc25B and Cdc2 in vitro.

Conclusion: CircHIPK3 promotes G2/M transition and induces PCa cell proliferation by sponging miR-338-3p and increasing the expression of Cdc25B and Cdc2. CircHIPK3 may play an oncogenic role in PCa.
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http://dx.doi.org/10.2147/OTT.S242482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7251229PMC
May 2020

Mitochondrial DNA Stimulates TLR9-Dependent Neutrophil Extracellular Trap Formation in Primary Graft Dysfunction.

Am J Respir Cell Mol Biol 2020 03;62(3):364-372

Department of Medicine.

The immune system is designed to robustly respond to pathogenic stimuli but to be tolerant to endogenous ligands to not trigger autoimmunity. Here, we studied an endogenous damage-associated molecular pattern, mitochondrial DNA (mtDNA), during primary graft dysfunction (PGD) after lung transplantation. We hypothesized that cell-free mtDNA released during lung ischemia-reperfusion triggers neutrophil extracellular trap (NET) formation via TLR9 signaling. We found that mtDNA increases in the BAL fluid of experimental PGD (prolonged cold ischemia followed by orthotopic lung transplantation) and not in control transplants with minimal warm ischemia. The adoptive transfer of mtDNA into the minimal warm ischemia graft immediately before lung anastomosis induces NET formation and lung injury. TLR9 deficiency in neutrophils prevents mtDNA-induced NETs, and TLR9 deficiency in either the lung donor or recipient decreases NET formation and lung injury in the PGD model. Compared with human lung transplant recipients without PGD, severe PGD was associated with high levels of BAL mtDNA and NETs, with evidence of relative deficiency in DNaseI. We conclude that mtDNA released during lung ischemia-reperfusion triggers TLR9-dependent NET formation and drives lung injury. In PGD, DNaseI therapy has a potential dual benefit of neutralizing a major NET trigger (mtDNA) in addition to dismantling pathogenic NETs.
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http://dx.doi.org/10.1165/rcmb.2019-0140OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7055700PMC
March 2020

Differential gene expression, including Sjfs800, in Schistosoma japonicum females at pre-pairing, initial pairing and oviposition.

Parasit Vectors 2019 Aug 23;12(1):414. Epub 2019 Aug 23.

Department of Microbiology and Parasitology, School of Basic Medical Sciences, Anhui Medical University, 81# Meishan Road, Hefei, 230032, Anhui, People's Republic of China.

Background: Schistosomiasis is a prevalent but neglected tropical disease caused by parasitic trematodes of the genus Schistosoma, with the primary disease-causing species being S. haematobium, S. mansoni and S. japonicum. Male-female pairing of schistosomes is necessary for sexual maturity and the production of a large number of eggs, which are primarily responsible for schistosomiasis dissemination and pathology.

Methods: Here, we used microarray hybridization, bioinformatics, quantitative PCR, in situ hybridization and gene silencing assays to identify genes that play critical roles in S. japonicum reproduction biology, particularly in vitellarium development, a process that affects male-female pairing, sexual maturation and subsequent egg production.

Results: Microarray hybridization analyses generated a comprehensive set of genes differentially transcribed before and after male-female pairing. Although the transcript profiles of females were similar 16 and 18 days after host infection, marked gene expression changes were observed at 24 days. The 30 most abundantly transcribed genes on day 24 included those associated with vitellarium development. Among these, the gene for female-specific 800 (fs800) was substantially upregulated. Our in situ hybridization results in female S. japonicum indicated that Sjfs800 mRNA was observed only in the vitellarium, localized in mature vitelline cells. Knocking down the Sjfs800 gene in female S. japonicum by approximately 60% reduced the number of mature vitelline cells, decreased rates of pairing and oviposition, and decreased the number of eggs produced in each male-female pairing by about 50%.

Conclusions: These results indicate that Sjfs800 may play a role in vitellarium development and egg production in S. japonicum and suggest that Sjfs800 regulation may provide a novel approach for the prevention or treatment of schistosomiasis.
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http://dx.doi.org/10.1186/s13071-019-3672-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6708146PMC
August 2019

Tyrosine kinase 4 is involved in the reproduction of the platyhelminth parasite Schistosoma japonicum.

Parasit Vectors 2017 Oct 18;10(1):498. Epub 2017 Oct 18.

Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology, School of Basic Medical Sciences, 81#Meishan Road, Hefei, Anhui, 230032, People's Republic of China.

Background: Schistosomiasis is one of the most common parasitic diseases affecting millions of humans and animals worldwide. Understanding the signal transduction pathways and the molecular basis of reproductive regulation in schistosomes is critically important for developing new strategies for preventing and treating these infections. Syk kinases regulate the proliferation, differentiation, morphogenesis, and survival of various types of cells and have been identified in invertebrates. Tyrosine kinase 4 (TK4), a member of the Syk kinase family, plays a pivotal role in gametogenesis in S. mansoni, affecting the development of the testis and ovaries in this parasite. The role of TK4, however, in the reproduction of S. japonicum is poorly understood.

Methods: Here, the complete coding sequence of TK4 gene in S. japonicum (SjTK4) was cloned and characterized. The expression of SjTK4 was analyzed at different life-cycle stages and in various tissues of S. japonicum by qPCR. Piceatannol, a Syk kinase inhibitor, was applied to S. japonicum in vitro. The piceatannol-induced morphological changes of the parasites were observed using confocal laser scanning microscopy and the alterations in important egg-shell synthesis-related genes were examined using qPCR analyses.

Results: SjTK4 mRNA was differentially expressed throughout the life-cycle of S. japonicum. SjTK4 mRNA was highly expressed in the ovary and testis of S. japonicum, with the level of gene expression significantly higher in males than in females. The expression levels of some important egg-shell synthesis related genes were higher in the piceatannol-treated groups than in the vehicle-treated control group and the number of eggs and germ cells also decreased in a concentration-dependent manner. Importantly, large pore-like structures can be found in the testis and ovaries of males and females after treating with piceatannol.

Conclusion: The results suggest that SjTK4 may play an important role in regulating gametogenesis of S. japonicum. The findings may help better understand the fundamental biology of S. japonicum. Moreover, the effect of S. japonicum treatment by piceatannol provides us with a new idea that inhibition of SjTK4 signaling pathway can effectively retard the development of the testis and ovaries.
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http://dx.doi.org/10.1186/s13071-017-2453-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648501PMC
October 2017

Functions of the Vasa gene in Schistosoma japonicum as assessed by RNA interference.

Gene 2018 Jan 28;638:13-19. Epub 2017 Sep 28.

Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology, Anhui Key Laboratory of Zoonoses, Anhui Medical University, 81#Meishan Road, Hefei, Anhui 230032, People's Republic of China. Electronic address:

Vasa, an enzyme belonging to the helicase family, contributes to the regulation of reproductive system development in many species. Thus, we hypothesized that the Vasa3 gene may function in the reproductive system of the parasite Schistosoma japonicum (S. japonicum), which is a major causative agent of schistosomiasis. It is a severe disease globally affecting humans and animals. To test this hypothesis, we firstly conducted whole mount in situ hybridization analyses and found that the S. japonicum Vasa3 (SjVasa3) gene was expressed mainly in the reproductive organs. We then explored the reproductive functions of Vasa3 in S. japonicum using RNA interference (RNAi) techniques. Coupled schistosomes collected from mice 28days post infection (dpi) were transfected three times with SjVasa3-specific small interfering RNA (siRNA) and cultured in vitro for up to 10days. As measured by quantitative PCR (qPCR) and Western blot analysis, levels of SjVasa3 mRNA and protein in Vasa siRNA treated worms were significantly reduced compared with untreated and scrambled siRNA treated worms. Confocal laser scanning microscopy (CLSM) images showed markedly siRNA induced changes in the morphology of the reproductive organs, especially in the female ovary, vitellarium and the male testes. SjVasa3 gene silencing also significantly reduced egg production. These data demonstrate that SjVasa3 is essential in reproductive organ development and egg production in S. japonicum, and could be a potential target for developing novel compounds to treat schistosomiasis.
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http://dx.doi.org/10.1016/j.gene.2017.09.054DOI Listing
January 2018

Function of Nanos1 gene in the development of reproductive organs of Schistosoma japonicum.

Parasitol Res 2017 May 28;116(5):1505-1513. Epub 2017 Mar 28.

Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology, Anhui Key Laboratory of Zoonoses, Anhui Medical University, No. 81 Meishan Road, Hefei, Anhui, 230032, People's Republic of China.

Nanos is a necessary factor in the differentiation and migration of primordial germ cells. It is closely associated with the development of genitalia in a wide range of species. We questioned whether Nanos was involved in the reproductive organ development of Schistosoma japonicum. Firstly, by in situ hybridization, S. japonicum Nanos1 (SjNanos1) gene was expressed mainly in reproductive organs of S. japonicum. Then, the paired schistosome of 28 days post-infection (dpi) was transfected with SjNanos1 small interfering RNA three times and cultured in vitro for 10 days. SjNanos1 expression suppression in the mRNA and protein levels were confirmed compared to that of the controls. The morphological changes in reproductive organs and egg production were observed after SjNanos1 gene knockdown. The results observed by confocal laser scanning microscopy showed significant changes in the morphology of reproductive organs of parasites, especially the female ovaries, vitellarium, and the male testes, after RNAi. In addition, SjNanos1 silencing also induced the reduction of eggs, and affected the changes of reproduction-related genes, like Pumilio, CNOT6L, and Fs800. Therefore, our findings demonstrate that the SjNanos1 gene is essential in the development of reproductive organs and the egg production of S. japonicum.
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http://dx.doi.org/10.1007/s00436-017-5427-9DOI Listing
May 2017

The lung is a site of platelet biogenesis and a reservoir for haematopoietic progenitors.

Nature 2017 04 22;544(7648):105-109. Epub 2017 Mar 22.

Department of Medicine, University of California, San Francisco (UCSF), San Francisco, California 94143, USA.

Platelets are critical for haemostasis, thrombosis, and inflammatory responses, but the events that lead to mature platelet production remain incompletely understood. The bone marrow has been proposed to be a major site of platelet production, although there is indirect evidence that the lungs might also contribute to platelet biogenesis. Here, by directly imaging the lung microcirculation in mice, we show that a large number of megakaryocytes circulate through the lungs, where they dynamically release platelets. Megakaryocytes that release platelets in the lungs originate from extrapulmonary sites such as the bone marrow; we observed large megakaryocytes migrating out of the bone marrow space. The contribution of the lungs to platelet biogenesis is substantial, accounting for approximately 50% of total platelet production or 10 million platelets per hour. Furthermore, we identified populations of mature and immature megakaryocytes along with haematopoietic progenitors in the extravascular spaces of the lungs. Under conditions of thrombocytopenia and relative stem cell deficiency in the bone marrow, these progenitors can migrate out of the lungs, repopulate the bone marrow, completely reconstitute blood platelet counts, and contribute to multiple haematopoietic lineages. These results identify the lungs as a primary site of terminal platelet production and an organ with considerable haematopoietic potential.
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http://dx.doi.org/10.1038/nature21706DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663284PMC
April 2017

Neutrophil extracellular traps are pathogenic in primary graft dysfunction after lung transplantation.

Am J Respir Crit Care Med 2015 Feb;191(4):455-63

1 Division of Pulmonary and Critical Care Medicine, Department of Medicine, and.

Rationale: Primary graft dysfunction (PGD) causes early mortality after lung transplantation and may contribute to late graft failure. No effective treatments exist. The pathogenesis of PGD is unclear, although both neutrophils and activated platelets have been implicated. We hypothesized that neutrophil extracellular traps (NETs) contribute to lung injury in PGD in a platelet-dependent manner.

Objectives: To study NETs in experimental models of PGD and in lung transplant patients.

Methods: Two experimental murine PGD models were studied: hilar clamp and orthotopic lung transplantation after prolonged cold ischemia (OLT-PCI). NETs were assessed by immunofluorescence microscopy and ELISA. Platelet activation was inhibited with aspirin, and NETs were disrupted with DNaseI. NETs were also measured in bronchoalveolar lavage fluid and plasma from lung transplant patients with and without PGD.

Measurements And Main Results: NETs were increased after either hilar clamp or OLT-PCI compared with surgical control subjects. Activation and intrapulmonary accumulation of platelets were increased in OLT-PCI, and platelet inhibition reduced NETs and lung injury, and improved oxygenation. Disruption of NETs by intrabronchial administration of DNaseI also reduced lung injury and improved oxygenation. In bronchoalveolar lavage fluid from human lung transplant recipients, NETs were more abundant in patients with PGD.

Conclusions: NETs accumulate in the lung in both experimental and clinical PGD. In experimental PGD, NET formation is platelet-dependent, and disruption of NETs with DNaseI reduces lung injury. These data are the first description of a pathogenic role for NETs in solid organ transplantation and suggest that NETs are a promising therapeutic target in PGD.
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http://dx.doi.org/10.1164/rccm.201406-1086OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351593PMC
February 2015

STIM1 calcium sensor is required for activation of the phagocyte oxidase during inflammation and host defense.

Blood 2014 Apr 3;123(14):2238-49. Epub 2014 Feb 3.

Department of Laboratory Medicine.

The stromal-interacting molecule 1 (STIM1) is a potent sensor of intracellular calcium, which in turn regulates entry of external calcium through plasma membrane channels to affect immune cell activation. Although the contribution of STIM1 to calcium signaling in lymphocytes has been well studied, the role of this protein in neutrophil-mediated inflammation and host defense is unknown. We report that STIM1-deficient murine neutrophils show loss of store-operated calcium entry (SOCE) in response to both soluble ligands that activate G-proteins as well as Fcγ-receptor or integrin ligation that activates tyrosine kinase signaling. This results in modest defects in phagocytosis and degranulation responses but a profound block in superoxide production by the phagocyte oxidase. We trace the primary intracellular target of calcium to be protein kinase C isoforms α and β (PKCα and PKCβ), which in turn phosphorylate subunits of the oxidase leading to superoxide production. In vivo the loss of SOCE in stim1(-/-) chimeric mice results in marked susceptibility to bacterial infections but also protection from tissue injury in hepatic ischemia/reperfusion injury. These results demonstrate the critical role of STIM1-mediated SOCE and define major protein targets of calcium signaling in neutrophil activation during inflammatory disease.
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http://dx.doi.org/10.1182/blood-2012-08-450403DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3975260PMC
April 2014

Heterotopic heart transplantation in mice.

J Vis Exp 2007 19(6):238. Epub 2007 Jul 19.

Department of Surgery, University of California, San Francisco, USA.

The mouse heterotopic heart transplantation has been used widely since it was introduced by Drs. Corry and Russell in 1973. It is particularly valuable for studying rejection and immune response now that newer transgenic and gene knockout mice are available, and a large number of immunologic reagents have been developed. The heart transplant model is less stringent than the skin transplant models, although technically more challenging. We have developed a modified technique and have completed over 1000 successful cases of heterotopic heart transplantation in mice. When making anastomosis of the ascending aorta and abdominal aorta, two stay sutures are placed at the proximal and distal apexes of recipient abdominal aorta with the donor s ascending aorta, then using 11-0 suture for anastomosis on both side of aorta with continuing sutures. The stay sutures make the anastomosis easier and 11-0 is an ideal suture size to avoid bleeding and thrombosis.When making anastomosis of pulmonary artery and inferior vena cava, two stay sutures are made at the proximal apex and distal apex of the recipient s inferior vena cava with the donor s pulmonary artery. The left wall of the inferior vena cava and donor s pulmonary artery is closed with continuing sutures in the inside of the inferior vena cava after, one knot with the proximal apex stay suture the right wall of the inferior vena cava and the donor s pulmonary artery are closed with continuing sutures outside the inferior vena cave with 10-0 sutures. This method is easier to perform because anastomosis is made just on the one side of the inferior vena cava and 10-0 sutures is the right size to avoid bleeding and thrombosis. In this article, we provide details of the technique to supplement the video.
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http://dx.doi.org/10.3791/238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2557111PMC
February 2009

Small bowel transplantation in mice.

J Vis Exp 2007 20(7):258. Epub 2007 Aug 20.

Department of Surgery, University of California, San Francisco, CA, USA.

Since 1990, the development of tacrolimus-based immunosuppression and improved surgical techniques, the increased array of potent immunosuppressive medications, infection prophylaxis, and suitable patient selection helped improve actuarial graft and patient survival rates for all types of intestine transplantation. Patients with irreversible intestinal failure and complications of parenteral nutrition should now be routinely considered for small intestine transplantation. However, Survival rates for small intestinal transplantation have been slow to improve compares increasingly favorably with renal, liver, heart and lung. The small bowel transplantation is still unsatisfactory compared with other organs. Further progress may depend on better understanding of immunology and physiology of the graft and can be greatly facilitated by animal models. A wider use of mouse small bowel transplantation model is needed in the study of immunology and physiology of the transplantation gut as well as efficient methods in diagnosing early rejection. However, this model is limited to use because the techniques involved is an extremely technically challenging. We have developed a modified technique. When making anastomosis of portal vein and inferior vena cava, two stay sutures are made at the proximal apex and distal apex of the recipient s inferior vena cava with the donor s portal vein. The left wall of the inferior vena cava and donor s portal vein is closed with continuing sutures in the inside of the inferior vena cava after, after one knot with the proximal apex stay suture the right wall of the inferior vena cava and the donor s portal vein are closed with continuing sutures outside the inferior vena cave with 10-0 sutures. This method is easier to perform because anastomosis is made just on the one side of the inferior vena cava and 10-0 sutures is the right size to avoid bleeding and thrombosis. In this article, we provide details of the technique to supplement the video.
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http://dx.doi.org/10.3791/258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2565857PMC
February 2009