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Wang J, Lu L, Zou G, Ye Z, Jin F, Wang L, Ke G, Dong K, Tao L. Transcriptomic Analysis of Retinal Gene in Experimental Retinal Detachment Rats and Exploration of S100A9 and TLR4 in Human Vitreous. Curr Eye Res 2023; 48:1170-1178. [PMID: 37846082 DOI: 10.1080/02713683.2023.2254016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 08/28/2023] [Indexed: 10/18/2023]
Abstract
PURPOSE To screen for the differentially expressed genes in experimental retinal detachment rats, and to explore the expression of S100 calcium-binding protein A9 and Toll-like receptor 4 in the vitreous of rhegmatogenous retinal detachment patients. METHODS Three rats of experimental retinal detachment and three normal rats were enrolled in the study. Transcriptomics (RNAseq) sequencing technology was used to screen differentially expressed genes in the retinas of the experimental retinal detachment group and the normal group. The selected differentially expressed genes for gene ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analysis were performed. In addition, the vitreous of 15 patients with rhegmatogenous retinal detachment and six patients with the control group were collected. The expressions of S100 calcium-binding protein A9 and Toll-like receptor 4 were detected by Elisa, and the differences in expression levels were analyzed statistically. RESULTS A total of 198 differentially expressed genes were screened by RNAseq sequencing, including 118 upregulated genes and 80 downregulated genes. Kyoto Encyclopedia of Genes and Genomes analysis confirmed that the most enriched pathway was the mitogen-activated protein kinase signaling pathway. Compared to the normal group, the expressions of suppressor of cytokine signaling-3, Storkhead box-2, S100 calcium-binding protein A9, Spi-1 proto-oncogene, phosphodiesterase 1B, and kinesin-light chain 1 mRNA in the retinas of the experimental retinal detachment rats were up-regulated, and the expressions of Max interacting protein 1 and the voltage-gated sodium 1 were down-regulated. Compared to the control group, the expressions of S100 calcium-binding protein A9 and Toll-like receptor 4 were upregulated by Elisa in the vitreous humor of rhegmatogenous retinal detachment patients with a statistically significant difference (p all <.05). CONCLUSION The differentially expressed genes of experimental retinal detachment rats were suppressor of cytokine signaling-3, Storkhead box-2, S100 calcium-binding protein A9, Spi-1 proto-oncogene, phosphodiesterase 1B, kinesin-light chain 1, Max interacting protein 1, voltage-gated sodium 1, etc. The differences of S100 calcium-binding protein A9 and Toll-like receptor 4 expressions between the rhegmatogenous retinal detachment patients and the control group were statistically significant, indicating that they may play a potential role in the inflammatory process of rhegmatogenous retinal detachment.
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Affiliation(s)
- Jing Wang
- Department of Ophthalmology, The Second Affiliated Hospital of Anhui Medical University, Hefei, China
- Department of Ophthalmology, Division of Life Sciences and Medicine, Eye Center, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Li Lu
- Department of Ophthalmology, Division of Life Sciences and Medicine, Eye Center, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Gaocheng Zou
- Department of Ophthalmology, The First Affiliated Hospital of Anhui University of Traditional Chinese Medicine, Hefei, China
| | - Ziyang Ye
- Department of Ophthalmology, Division of Life Sciences and Medicine, Eye Center, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Feiyu Jin
- Department of Ophthalmology, Division of Life Sciences and Medicine, Eye Center, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Lin Wang
- Department of Ophthalmology, Division of Life Sciences and Medicine, Eye Center, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Genjie Ke
- Department of Ophthalmology, Division of Life Sciences and Medicine, Eye Center, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Kai Dong
- Department of Ophthalmology, Division of Life Sciences and Medicine, Eye Center, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Liming Tao
- Department of Ophthalmology, The Second Affiliated Hospital of Anhui Medical University, Hefei, China
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2
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Stierschneider A, Wiesner C. Shedding light on the molecular and regulatory mechanisms of TLR4 signaling in endothelial cells under physiological and inflamed conditions. Front Immunol 2023; 14:1264889. [PMID: 38077393 PMCID: PMC10704247 DOI: 10.3389/fimmu.2023.1264889] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 11/08/2023] [Indexed: 12/18/2023] Open
Abstract
Toll-like receptor 4 (TLR4) are part of the innate immune system. They are capable of recognizing pathogen-associated molecular patterns (PAMPS) of microbes, and damage-associated molecular patterns (DAMPs) of damaged tissues. Activation of TLR4 initiates downstream signaling pathways that trigger the secretion of cytokines, type I interferons, and other pro-inflammatory mediators that are necessary for an immediate immune response. However, the systemic release of pro-inflammatory proteins is a powerful driver of acute and chronic inflammatory responses. Over the past decades, immense progress has been made in clarifying the molecular and regulatory mechanisms of TLR4 signaling in inflammation. However, the most common strategies used to study TLR4 signaling rely on genetic manipulation of the TLR4 or the treatment with agonists such as lipopolysaccharide (LPS) derived from the outer membrane of Gram-negative bacteria, which are often associated with the generation of irreversible phenotypes in the target cells or unintended cytotoxicity and signaling crosstalk due to off-target or pleiotropic effects. Here, optogenetics offers an alternative strategy to control and monitor cellular signaling in an unprecedented spatiotemporally precise, dose-dependent, and non-invasive manner. This review provides an overview of the structure, function and signaling pathways of the TLR4 and its fundamental role in endothelial cells under physiological and inflammatory conditions, as well as the advances in TLR4 modulation strategies.
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Affiliation(s)
| | - Christoph Wiesner
- Department Science & Technology, Institute Biotechnology, IMC Krems University of Applied Sciences, Krems, Austria
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3
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Liu L, Jiang Y, Steinle JJ. Loss of cystatin C regulates permeability and inflammatory pathways in retina. Microvasc Res 2023; 148:104510. [PMID: 36822364 PMCID: PMC10258155 DOI: 10.1016/j.mvr.2023.104510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/04/2023] [Accepted: 02/17/2023] [Indexed: 02/23/2023]
Abstract
Cystatin C has been linked to inflammation in other diseases, such as epilepsy and Alzheimer's disease. These studies were designed to investigate whether Cystatin C regulates retinal inflammation and permeability. To address this question, we used Cystatin C knockout mice in a retinal ischemia/reperfusion model to determine whether Cystatin C regulated retinal damage, as well as inflammatory mediators and retinal permeability. To support the mouse work, we also used primary retinal endothelial cells cultured in normal and high glucose. Ischemia/reperfusion in Cystatin C knockout mice caused increased formation of degenerate capillaries. Loss of Cystatin C increased fluorescein leakage in the retina, which was accompanied by reduced levels of zonula occludin 1 (ZO-1) and occludin proteins. When REC were grown in high glucose, recombinant Cystatin C decreased retinal permeability, while Cystatin C siRNA increased dextran flux compared to high glucose alone. Recombinant Cystatin C decreased levels of interleukin-1-beta (IL-1β) and high mobility group box 1 (HMGB1) levels. In conclusion, loss of Cystatin C increased vascular damage in response to ischemia/reperfusion. Cystatin C regulated permeability and inflammatory mediators in the retina in response to stressors. Cystatin C offers a new target for retinal disease therapeutic development.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Youde Jiang
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Jena J Steinle
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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4
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Mathew B, Acha LG, Torres LA, Huang CC, Liu A, Kalinin S, Leung K, Dai Y, Feinstein DL, Ravindran S, Roth S. MicroRNA-based engineering of mesenchymal stem cell extracellular vesicles for treatment of retinal ischemic disorders: Engineered extracellular vesiclesand retinal ischemia. Acta Biomater 2023; 158:782-797. [PMID: 36638942 PMCID: PMC10005109 DOI: 10.1016/j.actbio.2023.01.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 12/18/2022] [Accepted: 01/05/2023] [Indexed: 01/12/2023]
Abstract
Mesenchymal stem cell (MSCs)-derived extracellular vesicles (EVs) are emerging therapeutic tools. Hypoxic pre-conditioning (HPC) of MSCs altered the production of microRNAs (miRNAs) in EVs, and enhanced the cytoprotective, anti-inflammatory, and neuroprotective properties of their derivative EVs in retinal cells. EV miRNAs were identified as the primary contributors of these EV functions. Through miRNA seq analyses, miRNA-424 was identified as a candidate for the retina to overexpress in EVs for enhancing cytoprotection and anti-inflammatory effects. FEEs (functionally engineered EVs) overexpressing miR424 (FEE424) significantly enhanced neuroprotection and anti-inflammatory activities in vitro in retinal cells. FEE424 functioned by reducing inflammatory cytokine production in retinal microglia, and attenuating oxygen free radicals in retinal Muller cells and microvascular endothelial cells, providing a multi-pronged approach to enhancing recovery after retinal ischemic insult. In an in vivo model of retinal ischemia, native, HPC, and FEE424 MSC EVs robustly and similarly restored function to close to baseline, and prevented loss of retinal ganglion cells, but HPC EVs provided the most effective attenuation of apoptosis-related and inflammatory cytokine gene expression. These results indicate the potential for EV engineering to produce ameliorative effects for retinal diseases with a significant inflammatory component. STATEMENT OF SIGNIFICANCE: We show that functionally engineered extracellular vesicles (FEEs) from mesenchymal stem cells (MSCs) provide cytoprotection in rat retina subjected to ischemia. FEEs overexpressing microRNA 424 (FEE424) function by reducing inflammatory cytokine production in retinal microglia, and attenuating oxygen free radicals in Muller cells and microvascular endothelial cells, providing a multi-pronged approach to enhancing recovery. In an in vivo model of retinal ischemia in rats, native, hypoxic-preconditioned (HPC), and FEE424 MSC EVs robustly and similarly restored function, and prevented loss of retinal ganglion cells, but HPC EVs provided the most effective attenuation of apoptosis-related and inflammatory cytokine gene expression. The results indicate the potential for EV engineering to produce ameliorative effects for retinal diseases with a significant inflammatory component.
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Affiliation(s)
- Biji Mathew
- Department of Anesthesiology, College of Medicine, University of Illinois-Chicago
| | - Lorea Gamboa Acha
- Department of Anesthesiology, College of Medicine, University of Illinois-Chicago
| | - Leianne A Torres
- Department of Anesthesiology, College of Medicine, University of Illinois-Chicago
| | - Chun-Chieh Huang
- Department of Oral Biology, College of Dentistry, University of Illinois-Chicago
| | - Alice Liu
- Department of Anesthesiology, College of Medicine, University of Illinois-Chicago
| | - Sergey Kalinin
- Department of Anesthesiology, College of Medicine, University of Illinois-Chicago
| | - Kasey Leung
- Department of Oral Biology, College of Dentistry, University of Illinois-Chicago
| | - Yang Dai
- Department of Bioengineering, College of Engineering, University of Illinois-Chicago
| | - Douglas L Feinstein
- Department of Anesthesiology, College of Medicine, University of Illinois-Chicago; Jesse Brown Veterans Affairs, Chicago, IL
| | - Sriram Ravindran
- Department of Oral Biology, College of Dentistry, University of Illinois-Chicago.
| | - Steven Roth
- Department of Anesthesiology, College of Medicine, University of Illinois-Chicago.
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Liu L, Jiang Y, Steinle JJ. TNFAIP3 may be key to TLR4-activation of the inflammasome in the retinal vasculature. Exp Eye Res 2022; 220:109108. [PMID: 35568203 DOI: 10.1016/j.exer.2022.109108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/08/2022] [Accepted: 05/06/2022] [Indexed: 11/04/2022]
Abstract
The goal of these studies were to determine whether tumor necrosis factor, alpha-induced protein 3 (TNFAIP3) regulated toll-like receptor 4 (TLR4) actions on the NOD-like receptor protein 3 (NLRP3) inflammasome. Western blotting was done on retinal lysates from TLR4 floxed and endothelial cell specific TLR4 knockout mice for TNFAIP3, TLR4, and NLRP3 pathway proteins. Retinal endothelial cells (REC) were grown in normal (5mM) and high glucose (25mM) and treated with TNFAIP3 siRNA, followed by Western blotting for TLR4 and NLRP3 pathway proteins. Loss of TLR4 in endothelial cells increased TNFAIP3 levels, while decreasing NLRP3 pathway proteins. High glucose culturing conditions increased TLR4 and NLRP3 proteins, which were also increased by TNFAIP3 siRNA. Data demonstrate that TLR4 regulates NLRP3 pathway proteins. TNFAIP3 can regulate TLR4 and the NLRP3 pathway. TNFAIP3 may offer a new target for therapeutic development against retinal inflammation.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Youde Jiang
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Jena J Steinle
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
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Titi-Lartey O, Mohammed I, Amoaku WM. Toll-Like Receptor Signalling Pathways and the Pathogenesis of Retinal Diseases. FRONTIERS IN OPHTHALMOLOGY 2022; 2:850394. [PMID: 38983565 PMCID: PMC11182157 DOI: 10.3389/fopht.2022.850394] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 03/08/2022] [Indexed: 07/11/2024]
Abstract
There is growing evidence that the pathogenesis of retinal diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD) have a significant chronic inflammatory component. A vital part of the inflammatory cascade is through the activation of pattern recognition receptors (PRR) such as toll-like receptors (TLR). Here, we reviewed the past and current literature to ascertain the cumulative knowledge regarding the effect of TLRs on the development and progression of retinal diseases. There is burgeoning research demonstrating the relationship between TLRs and risk of developing retinal diseases, utilising a range of relevant disease models and a few large clinical investigations. The literature confirms that TLRs are involved in the development and progression of retinal diseases such as DR, AMD, and ischaemic retinopathy. Genetic polymorphisms in TLRs appear to contribute to the risk of developing AMD and DR. However, there are some inconsistencies in the published reports which require further elucidation. The evidence regarding TLR associations in retinal dystrophies including retinitis pigmentosa is limited. Based on the current evidence relating to the role of TLRs, combining anti-VEGF therapies with TLR inhibition may provide a longer-lasting treatment in some retinal vascular diseases.
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Affiliation(s)
| | | | - Winfried M. Amoaku
- Academic Ophthalmology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
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7
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Liu L, Jiang Y, Steinle JJ. Prohibitin 1 Regulates Inflammatory Mediators and Reactive Oxygen Species in Retinal Endothelial Cells. J Clin Med 2022; 11:jcm11071915. [PMID: 35407523 PMCID: PMC9000038 DOI: 10.3390/jcm11071915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/15/2022] [Accepted: 03/28/2022] [Indexed: 11/16/2022] Open
Abstract
Diabetic retinopathy is associated with increased inflammatory mediator levels. In these studies, we focused on prohibitin 1. We performed western blotting for retinal lysates from diabetic mice and Epac1 floxed and cdh5Cre-Epac1 mice. We also grew primary retinal endothelial cells (REC) in normal (5 mM) and high (25 mM) glucose, and treated some cells with an Epac 1 agonist or prohibitin 1 siRNA. Western blotting was done to confirm knockdown of prohibitin 1 and Epac 1 agonism. We measured the tumor necrosis factor alpha (TNFα), interleukin-1-beta (IL-1β), phosphorylated prohibitin 1, phosphorylated nuclear factor kappa beta (NFkB), high mobility group box 1 (HMGB1) and reactive oxygen species (ROS) levels in REC after transfection with prohibitin 1 siRNA. Results showed that high glucose increased the inflammatory mediators, as well as HMGB1 and ROS. The levels of ROS, HMGB1, and inflammatory pathways were all reduced after cells were transfected with prohibitin 1 siRNA. Epac1 reduced prohibitin 1 phosphorylation. In conclusion, decreased prohibitin 1 significantly reduced the inflammatory mediator and ROS levels in REC. Epac1 regulates the prohibitin 1 levels in REC.
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8
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Liu L, Jiang Y, Steinle JJ. Epac1 and PKA regulate of P2X7 and NLRP3 inflammasome proteins in the retinal vasculature. Exp Eye Res 2022; 218:108987. [PMID: 35182568 PMCID: PMC9050870 DOI: 10.1016/j.exer.2022.108987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/01/2022] [Accepted: 02/10/2022] [Indexed: 02/02/2023]
Abstract
Others have shown that the purinergic 2X7 receptor (P2X7R) and the NOD-like receptor family protein 3 (NLRP3) inflammasome are involved in multiple inflammatory diseases. In this study, we tested whether Epac1 and PKA lie upstream of P2X7R actions on the NLRP3 inflammasome. We also evaluated whether eye drops of a P2X7R inhibitor protected the retina against ischemia/reperfusion (I/R) injury by measuring retinal thickness and degenerate capillary formation after exposure to I/R and treatment with A438079 eye drops. Mice were exposed to the I/R model followed by eye drops of A438079 for 2 or 10 days. Additionally, primary human retinal endothelial cells (REC) grown in normal and high glucose were treated with ATP (to stimulate P2X7R), an Epac1 agonist, or forskolin (to stimulate PKA), followed by measurements of P2X7R and NLRP3 inflammasome proteins. Eye drops containing A438079 protected the retina against neuronal and vascular damage after exposure to I/R. When REC were treated with ATP to stimulate P2X7R, NLRP3 inflammasome proteins were all increased compared to high glucose only. Epac1 and PKA agonists reduced P2X7R levels in REC grown in high glucose. In conclusion, these data suggest that P2X7 regulates retinal responses to the I/R stress, and that P2X7 increases NLRP3 inflammasome proteins in human REC. Epac1 and PKA can inhibit of P2X7, which will reduce NLRP3 inflammasome proteins in REC grown in high glucose.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Youde Jiang
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Jena J Steinle
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
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Liu L, Jiang Y, Steinle JJ. Epac1 and PKA agonists inhibit ROS to reduce NLRP3 inflammasome proteins in retinal endothelial cells. Mol Vis 2022; 28:500-506. [PMID: 37089701 PMCID: PMC10115359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 12/29/2022] [Indexed: 04/25/2023] Open
Abstract
Purpose Reactive oxygen species (ROS) activate inflammatory pathways in several organs, including the retina. More recent work has shown that ROS activate the NOD-like receptor protein 3 (NLRP3) inflammasome pathway proteins. We recently showed that the exchange protein activated by cAMP 1 (Epac1) and protein kinase A (PKA) regulates NLRP3 proteins in the retina. Our goal was to determine whether Epac1 and PKA reduce ROS and NLRP3 inflammasome proteins. Methods We used human primary retinal endothelial cells (RECs) grown in normal glucose (5 mM) and stimulated in normal glucose with hydrogen peroxide (H2O2) to induce ROS and measured NLRP3 pathway proteins. In some groups, we treated cells with an Epac1 or a PKA agonist in addition to H2O2 treatment to determine whether Epac1 and PKA reduced ROS and induced NLRP3 pathway proteins. Results The data showed that 500 µM H2O2 was the optimal dose to increase ROS in RECs. In RECs treated with H2O2, NLRP3 pathway proteins were increased, which were significantly reduced by cotreatment with PKA or Epac1 agonists. H2O2 significantly increased NIMA-related kinase 7 (Nek7) and purinergic 2X7 receptor 7 (P2X7) levels, which were blocked by Epac1 and PKA agonists. Conclusions Taken together, these data suggest that Epac1 and PKA reduce retinal inflammation through the reduced ROS-induced activation of NLRP3 pathway proteins.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI
| | - Youde Jiang
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI
| | - Jena J Steinle
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI
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Rudraraju M, Narayanan SP, Somanath PR. Distinct Mechanisms of Human Retinal Endothelial Barrier Modulation In Vitro by Mediators of Diabetes and Uveitis. Life (Basel) 2021; 12:life12010033. [PMID: 35054426 PMCID: PMC8779223 DOI: 10.3390/life12010033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/30/2021] [Accepted: 12/10/2021] [Indexed: 12/04/2022] Open
Abstract
Ocular diseases such as diabetic retinopathy (DR) and uveitis are associated with injury to the blood–retinal barrier (BRB). Whereas high glucose (HG) and advanced glycation end products (AGE) contribute to DR, bacterial infections causing uveitis are triggered by endotoxins such as lipopolysaccharide (LPS). It is unclear how HG, AGE, and LPS affect human retinal endothelial cell (HREC) junctions. Moreover, tumor necrosis factor-α (TNFα) is elevated in both DR and ocular infections. In the current study, we determined the direct effects of HG, AGE, TNFα, and LPS on the expression and intracellular distribution of claudin-5, VE-cadherin, and β-catenin in HRECs and how these mediators affect Akt and P38 MAP kinase that have been implicated in ocular pathologies. In our results, whereas HG, AGE, and TNFα activated both Akt and P38 MAPK, LPS treatment suppressed Akt but increased P38 MAPK phosphorylation. Furthermore, while treatment with AGE and HG increased cell-junction protein expression in HRECs, LPS elicited a paradoxical effect. By contrast, when HG treatment increased HREC-barrier resistance, AGE and LPS stimulation compromised it, and TNFα had no effect. Together, our results demonstrated the differential effects of the mediators of diabetes and infection on HREC-barrier modulation leading to BRB injury.
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Affiliation(s)
- Madhuri Rudraraju
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA;
- Research Division, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - S. Priya Narayanan
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA;
- Research Division, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Correspondence: (S.P.N.); (P.R.S.); Tel.: +1-706-721-4250 (P.R.S.)
| | - Payaningal R. Somanath
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA;
- Research Division, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Correspondence: (S.P.N.); (P.R.S.); Tel.: +1-706-721-4250 (P.R.S.)
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11
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Rong Z, Huang Y, Cai H, Chen M, Wang H, Liu G, Zhang Z, Wu J. Gut Microbiota Disorders Promote Inflammation and Aggravate Spinal Cord Injury Through the TLR4/MyD88 Signaling Pathway. Front Nutr 2021; 8:702659. [PMID: 34589510 PMCID: PMC8473614 DOI: 10.3389/fnut.2021.702659] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/23/2021] [Indexed: 12/02/2022] Open
Abstract
Background: In spinal cord injury (SCI), systemic inflammation and the death of nerve cells in the spinal cord are life threatening. The connection between gut microbiota and signaling pathways has been a hot research topic in recent years. The Toll-like receptor 4/Myeloid differentiation factor 88 (TLR4/MyD88) signaling pathway is closely related to the inflammatory response. This study explored whether the gut microbiota imbalance could affect the TLR4/MyD88 signaling pathway to regulate SCI to provide a new basis for SCI research and treatment. Methods: An SCI model was constructed to study the influence on the injury of gut microbiota. 16S amplicon sequencing was used to identify the diversity and abundance of gut microbes. Fecal microbiota transplantation was performed in mice with SCI. ELISA was used to detect the serum levels of pro-inflammatory and anti-inflammatory factors in mice. Hematoxylin and eosin staining was used to observe SCI in mice. Immunofluorescence was used to detect the rates of loss glial fibrillary acidic protein (GFAP), neuronal nuclear protein (NeuN), and ionized calcium-binding adapter molecule 1 (IBA1) in the spinal cord as indicators of apoptosis. The expression of the TLR4/MyD88 signaling pathway was detected by qRT-PCR and western blotting. Results: Significant differences were observed in the gut microbiota of SCI mice and normal mice. The gut microbiota of SCI mice was imbalanced. The levels of pro-inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in SCI mice were increased, as was the level of the toxic induced nitric oxide synthase. The levels of anti-inflammatory factors IL-4, transforming growth factor-β, and IL-10 were decreased, as was the level of arginase-1. The apoptosis rates of GFAP, NeuN, and IBA1 were increased. The TLR4/MyD88 signaling pathway was activated. In the SCI group, inflammation increased after fecal transplantation, apoptosis of GFAP, NeuN, and IBA1 increased, and SCI was more serious. Conclusion: The TLR4/MyD88 signaling pathway promotes the death of nerve cells by inducing inflammation. Gut microbiota dysregulation can lead to aggravated SCI by activating the TLR4/MyD88 signaling pathway.
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Affiliation(s)
- Zijie Rong
- Department of Spine Surgery, Huizhou Municipal Central Hospital, Huizhou, China.,Orthopaedic Institute, Huizhou Municipal Central Hospital, Huizhou, China
| | - Yuliang Huang
- Orthopaedic Institute, Huizhou Municipal Central Hospital, Huizhou, China.,Department of Orthopaedics, Huizhou Municipal Central Hospital, Huizhou, China
| | - Honghua Cai
- Department of Spine Surgery, Huizhou Municipal Central Hospital, Huizhou, China.,Orthopaedic Institute, Huizhou Municipal Central Hospital, Huizhou, China
| | - Min Chen
- Department of Spine Surgery, Huizhou Municipal Central Hospital, Huizhou, China.,Orthopaedic Institute, Huizhou Municipal Central Hospital, Huizhou, China
| | - Hao Wang
- Department of Spine Surgery, Huizhou Municipal Central Hospital, Huizhou, China.,Orthopaedic Institute, Huizhou Municipal Central Hospital, Huizhou, China
| | - Guihua Liu
- Department of Spine Surgery, Huizhou Municipal Central Hospital, Huizhou, China.,Orthopaedic Institute, Huizhou Municipal Central Hospital, Huizhou, China
| | - Zhiwen Zhang
- Orthopaedic Institute, Huizhou Municipal Central Hospital, Huizhou, China.,Department of Orthopaedics, Huizhou Municipal Central Hospital, Huizhou, China
| | - Jiawen Wu
- Department of Spine Surgery, The People's Hospital of Longhua, Shenzhen Longhua Clinical Medical College of Guangdong Medical University, Shenzhen, China
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Liu L, Jiang Y, Steinle JJ. Forskolin regulates retinal endothelial cell permeability through TLR4 actions in vitro. Mol Cell Biochem 2021; 476:4487-4492. [PMID: 34499321 DOI: 10.1007/s11010-021-04252-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/20/2021] [Indexed: 01/09/2023]
Abstract
To investigate whether forskolin, a protein kinase A agonist, regulates toll-like receptor 4 actions on retinal endothelial cell permeability in vitro. We also evaluated whether PKA could regulate TLR4 signaling independent of exchange protein activated by cAMP in REC in culture. REC were grown in normal (5 mM) or high (25 mM) glucose. Cells were treated with forskolin to increase PKA levels, siRNA against TLR4, siRNA against myeloid differentiation primary response 88, siRNA against translocating chain associated membrane protein 1, siRNA against epac1, or scrambled siRNA, or a combination of these treatments. Western blotting was done for zonula occludens 1 and occludin protein levels, as well as TLR4 signaling cascade proteins. Permeability measurements were done for REC in culture following inhibition of TLR4 or its signaling cascades. Forskolin restored high glucose-associated decreases in ZO-1 and occludin, which was associated with improved in vitro permeability levels. Both forskolin and TLR4 inhibition reduced high glucose-induced increases in REC permeability, but the actions were not cooperative. Forskolin regulated both MyD88-dependent and -independent signaling pathways, independent of Epac1. Finally, blockade of MyD88 or TRAM1 reduced permeability in REC grown in high glucose. A PKA agonist regulated TLR4 signaling independent of Epac1. PKA agonism or TLR4 inhibition is effective at reducing high glucose-induced permeability in REC in vitro. These studies offer new avenues for therapeutic development.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Youde Jiang
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jena J Steinle
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA.
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Liu L, Jiang Y, Steinle J. Epac1 regulates TLR4 signaling in the diabetic retinal vasculature. Cytokine 2021; 144:155576. [PMID: 34020266 DOI: 10.1016/j.cyto.2021.155576] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/09/2021] [Accepted: 05/04/2021] [Indexed: 01/08/2023]
Abstract
Toll-like receptor 4 (TLR4) polymorphisms occur in diabetic patients. Previous work showed that TLR4 is in the retina of diabetic mice, as well as in retinal endothelial cells (REC) and Müller cells. Since we have shown that exchange protein activated by cAMP 1 (Epac1) can reduce inflammatory mediators, we hypothesized that Epac1 would inhibit TLR4 signaling. We also hypothesized that direct TLR4 inhibition would protect the diabetic retina. Human REC in normal and high glucose were treated with an Epac1 agonist to explore the actions of Epac1 on TLR4 signaling in vitro. Subsequently, 2-month diabetic endothelial cell specific knockout mice for Epac1 (Cdh5Cre-Epac1) and Epac1 floxed mice retinas were used for Western blotting for TLR4 signaling pathways. We also used direct inhibition of TLR4 via Tak242 to investigate diabetes-induced changes in retinal permeability and neuronal loss in the mice. The Epac1 agonist reduced TLR4 signaling in REC grown in high glucose. TLR4 levels and both MyD88-dependent and -independent signaling pathways are increased in Cdh5Cre-Epac1 mice compared to Epac1 floxed mice. Tak242 reduced TLR4 signaling in diabetic mice and reduced diabetes-induced increases in permeability and cell loss in the ganglion cell layer in the Epac1 floxed and Cdh5Cre-Epac1 mice. In conclusion, Epac1 reduced TLR4 signaling in the retina and in REC. Direct inhibition of TLR4 was able to protect the retina against diabetes-induced changes in permeability and cell numbers in the ganglion cell layer.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - Youde Jiang
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - Jena Steinle
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, United States.
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Seidel A, Liu L, Jiang Y, Steinle JJ. Loss of TLR4 in endothelial cells but not Müller cells protects the diabetic retina. Exp Eye Res 2021; 206:108557. [PMID: 33789141 DOI: 10.1016/j.exer.2021.108557] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 03/10/2021] [Accepted: 03/24/2021] [Indexed: 01/01/2023]
Abstract
Others have previously reported that global loss of toll-like receptor 4 (TLR4) reduced retinal inflammation. To determine cell specific actions of TLR4 in the retina, we generated diabetic endothelial cell specific and Müller cell specific TLR4 knockout mice. Diabetic Cdh5-Cre TLR4 mice, PDGFRα-Cre TLR4 mice, and TLR4 floxed mice were evaluated for retinal permeability, neuronal damage, and numbers of degenerate capillaries, all changes commonly observed in the diabetic retina. We also measured protein levels of key inflammatory mediators. We found that diabetes increased permeability, neuronal, and vascular damage in all mice. Loss of TLR4 in the retinal endothelial cells protected against these changes when compared to diabetic TLR4 floxed mice. In contrast, loss of TLR4 in Müller cells did not reduce diabetes-induced increases in permeability or neuronal and vascular damage. Elimination of TLR4 in either mouse model reduced inflammatory mediators, as well as VEGF levels. Taken together, our findings suggest that loss of TLR4 in endothelial cells is protective against diabetic-induced damage, while Müller cell TLR4 is not involved in the damage.
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Affiliation(s)
- Adam Seidel
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Li Liu
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Youde Jiang
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jena J Steinle
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA.
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15
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Liu G, Lu Y, Shi L, Ren Y, Kong J, Zhang M, Chen M, Liu W. TLR4-MyD88 signaling pathway is responsible for acute lung inflammation induced by reclaimed water. JOURNAL OF HAZARDOUS MATERIALS 2020; 396:122586. [PMID: 32315938 DOI: 10.1016/j.jhazmat.2020.122586] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/28/2020] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
Previous research found that inhalation exposure of reclaimed water could cause severe pulmonary inflammation, and the endotoxin was proposed to be the key risk factor. To further support this view, the toxic effects of different reclaimed water induced by acute inhalation exposure were compared between wildtype C57BL/6J and TLR4 signaling pathway defect mice. It was found that reclaimed water with high levels of endotoxin could induce strong inflammation in wildtype mice, but not in Tlr4-/- and MyD88-/- mutants. The mixed bacterial culture from the reclaimed water showed very weak response in wildtype mice and no response in TLR4-signaling pathway deficient mice, which further suggested that the cell-bound endotoxins contribute little in the inflammation induced by reclaimed water. In addition, conditional knockout of the Tlr4 gene in myeloid cells resulted in a significant reduction of sensitivity to the reclaimed water in mutants, which indicates that myeloid cells play the most important role in the defensive immune system against the pollutants in the water. In general, this study demonstrated that the TLR4-MyD88 signaling pathway is responsible for the acute lung inflammation induced by reclaimed water, which excludes the possibility of other signaling pathway dependent inflammation inducers in reclaimed water.
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Affiliation(s)
- Gang Liu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Yun Lu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
| | - Liangliang Shi
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Yunru Ren
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Jiayang Kong
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Mengyu Zhang
- School of Life Science, Tsinghua University, Beijing, 100084, China
| | - Menghao Chen
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Wanli Liu
- School of Life Science, Tsinghua University, Beijing, 100084, China
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Famakin BM, Vemuganti R. Toll-Like Receptor 4 Signaling in Focal Cerebral Ischemia: a Focus on the Neurovascular Unit. Mol Neurobiol 2020; 57:2690-2701. [PMID: 32306272 DOI: 10.1007/s12035-020-01906-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/19/2020] [Indexed: 12/14/2022]
Abstract
A robust innate immune activation leads to downstream expression of inflammatory mediators that amplify tissue damage and consequently increase the morbidity after stroke. The Toll-like receptor 4 (TLR4) pathway is a major innate immune pathway activated acutely and chronically after stroke. Hence, understanding the intricacies of the temporal profile, specific control points, and cellular specificity of TLR4 activation is crucial for the development of any novel therapeutics targeting the endogenous innate immune response after focal cerebral ischemia. The goal of this review is to summarize the current findings related to TLR4 signaling after stroke with a specific focus on the components of the neurovascular unit such as astrocytes, neurons, endothelial cells, and pericytes. In addition, this review will examine the effects of focal cerebral ischemia on interaction of these neurovascular unit components.
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Affiliation(s)
| | - R Vemuganti
- Department of Neurological Surgery, University of Wisconsin, Madison, WI, USA
- William S. Middleton VA Hospital, Madison, WI, USA
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Brichacek AL, Benkovic SA, Chakraborty S, Nwafor DC, Wang W, Jun S, Dakhlallah D, Geldenhuys WJ, Pinkerton AB, Millán JL, Brown CM. Systemic inhibition of tissue-nonspecific alkaline phosphatase alters the brain-immune axis in experimental sepsis. Sci Rep 2019; 9:18788. [PMID: 31827139 PMCID: PMC6906465 DOI: 10.1038/s41598-019-55154-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 11/19/2019] [Indexed: 12/27/2022] Open
Abstract
Tissue-nonspecific alkaline phosphatase (TNAP) is a ubiquitous enzyme present in many cells and tissues, including the central nervous system. Yet its functions at the brain-immune axis remain unclear. The goal of this study was to use a novel small molecular inhibitor of TNAP, SBI-425, to interrogate the function of TNAP in neuroimmune disorders. Following intraperitoneal (IP) administration of SBI-425, mass spectrometry analysis revealed that the SBI-425 does not cross the blood-brain barrier (BBB) in healthy mice. To elucidate the role of TNAP at the brain-immune axis, mice were subjected to experimental sepsis and received either vehicle or SBI-425 (25 mg/kg, IP) daily for 7 days. While SBI-425 administration did not affect clinical severity outcomes, we found that SBI-425 administration suppressed CD4 + Foxp3+ CD25- and CD8 + Foxp3+ CD25- splenocyte T-cell populations compared to controls. Further evaluation of SBI-425's effects in the brain revealed that TNAP activity was suppressed in the brain parenchyma of SBI-425-treated mice compared to controls. When primary brain endothelial cells were treated with a proinflammatory stimulus the addition of SBI-425 treatment potentiated the loss of barrier function in BBB endothelial cells. To further demonstrate a protective role for TNAP at endothelial barriers within this axis, transgenic mice with a conditional overexpression of TNAP were subjected to experimental sepsis and found to have increased survival and decreased clinical severity scores compared to controls. Taken together, these results demonstrate a novel role for TNAP activity in shaping the dynamic interactions within the brain-immune axis.
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Affiliation(s)
- Allison L Brichacek
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Stanley A Benkovic
- Department of Neuroscience, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Sreeparna Chakraborty
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Divine C Nwafor
- Department of Neuroscience, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Wei Wang
- Department of Neuroscience, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Sujung Jun
- Department of Physiology and Pharmacology, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Duaa Dakhlallah
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Werner J Geldenhuys
- Department of Pharmaceutical Sciences, School of Pharmacy, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | | | - José Luis Millán
- Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Candice M Brown
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA.
- Department of Neuroscience, School of Medicine, Center for Basic and Translational Stroke Research, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA.
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Commensal Escherichia coli Aggravates Acute Necrotizing Pancreatitis through Targeting of Intestinal Epithelial Cells. Appl Environ Microbiol 2019; 85:AEM.00059-19. [PMID: 30979838 DOI: 10.1128/aem.00059-19] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/04/2019] [Indexed: 12/14/2022] Open
Abstract
An increase of Escherichia-Shigella was previously reported in acute necrotizing pancreatitis (ANP). We investigated whether Escherichia coli MG1655, an Escherichia commensal organism, increased intestinal injury and aggravated ANP in rats. ANP was induced by retrograde injection of 3.5% sodium taurocholate into the biliopancreatic duct. Using gut microbiota-depleted rats, we demonstrated that gut microbiota was involved in the pancreatic injury and intestinal barrier dysfunction in ANP. Using 16S rRNA gene sequencing and quantitative PCR, we found intestinal dysbiosis and a significant increase of E. coli MG1655 in ANP. Afterward, administration of E. coli MG1655 by gavage to gut microbiota-depleted rats with ANP was performed. We observed that after ANP induction, E. coli MG1655-monocolonized rats presented more severe injury in the pancreas and intestinal barrier function than gut microbiota-depleted rats. Furthermore, Toll-like receptor 4 (TLR4)/MyD88/p38 mitogen-activated protein (MAPK) and endoplasmic reticulum stress (ERS) activation in intestinal epithelial cells were also increased more significantly in the MG1655-monocolonized ANP rats. In vitro, the rat ileal epithelial cell line IEC-18 displayed aggravated tumor necrosis factor alpha-induced inflammation and loss of tight-junction proteins in coculture with E. coli MG1655, as well as TLR4, MyD88, and Bip upregulation. In conclusion, our study shows that commensal E. coli MG1655 increases TLR4/MyD88/p38 MAPK and ERS signaling-induced intestinal epithelial injury and aggravates ANP in rats. Our study also describes the harmful potential of commensal E. coli in ANP.IMPORTANCE This study describes the harmful potential of commensal E. coli in ANP, which has not been demonstrated in previous studies. Our work provides new insights into gut bacterium-ANP cross talk, suggesting that nonpathogenic commensals could also exhibit adverse effects in the context of diseases.
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You ZP, Yu MJ, Zhang YL, Shi K. Progranulin protects the mouse retina under hypoxic conditions via inhibition of the Toll‑like receptor‑4‑NADPH oxidase 4 signaling pathway. Mol Med Rep 2018; 19:382-390. [PMID: 30431085 PMCID: PMC6297797 DOI: 10.3892/mmr.2018.9634] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 10/12/2018] [Indexed: 12/11/2022] Open
Abstract
To investigate the function of progranulin on the retina under hypoxic conditions, 8-week-old C57BL/6 mice were divided into normal condition and hypoxic condition groups (n=24 mice/group). The hypoxia model was established through intravitreal injection of 9 mM cobalt chloride. Subsequently, 10 mM progranulin and an equal amount of PBS were injected into the right and left eyes, respectively. Photoreceptor function was examined using electroretinogram (ERG) analysis. Morphological alterations were examined using immunofluorescence co-localization, retinal vascular inflammation was examined using the leukostasis assay, and signaling pathways were screened using immunoblotting. The results revealed that ERG amplitude was significantly lower under hypoxic conditions compared with under normal conditions. Furthermore, the amplitude was significantly reduced in the PBS-injected eyes compared with in the progranulin-injected eyes. Morphological examination demonstrated that the number of rods in the PBS-injected eyes was decreased compared with in the progranulin-injected eyes under hypoxic conditions. In addition, the arrangement of the cones was sparse and the morphology of the outer segments was short and small. Although the number of adherent leukocytes in the progranulin-injected eyes was higher in the hypoxic mice compared with in those under normal conditions, the number was only 52.31% of the number detected in the PBS-injected eyes. Analysis of the signaling pathways demonstrated that the protective effects of progranulin on retinas under hypoxic conditions were regulated by the Toll-like receptor 4 (TLR4)-NADPH oxidase 4 (NOX4) pathway, instead of the caspase and Wnt/β-catenin pathways. In conclusion, progranulin exerted protective effects on the function and morphology of photoreceptors in a hypoxic environment, and could reduce retinal vascular inflammation, through inhibition of the TLR4-NOX4 pathway.
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Affiliation(s)
- Zhi-Peng You
- Department of Ophthalmology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Meng-Jia Yu
- Department of Ophthalmology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Yu-Lan Zhang
- Department of Ophthalmology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Ke Shi
- Department of Ophthalmology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
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Junyuan Z, Hui X, Chunlan H, Junjie F, Qixiang M, Yingying L, Lihong L, Xingpeng W, Yue Z. Quercetin protects against intestinal barrier disruption and inflammation in acute necrotizing pancreatitis through TLR4/MyD88/p38 MAPK and ERS inhibition. Pancreatology 2018; 18:742-752. [PMID: 30115563 DOI: 10.1016/j.pan.2018.08.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 07/20/2018] [Accepted: 08/05/2018] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To investigate the effects of quercetin on intestinal barrier disruption and inflammation in acute necrotizing pancreatitis (ANP) in rats, and its possible mechanism. METHODS ANP was established by retrograde injection of 3.5% sodium taurocholate into the biliopancreatic duct, and quercetin (50 mg/kg × 3) was administered by intraperitoneal injection prior to and after ANP induction. Pancreatitis was assessed by pancreatic histopathology, plasma amylase, pancreatic myeloperoxidase (MPO) activity, IL-1β, TNFα and IL-6 levels. Injury of the distal ileum was assessed by histological evaluation. The ultrastructural changes of ileal epithelial cells were examined by transmission electron microscope (TEM). Intestinal barrier function was estimated by plasma diamine oxidase (DAO), d-lactate, endotoxin; and intestinal tight junction proteins including zonula occludens-1 (ZO-1), claudin 1, occludin; and bacterial translocation. Intestinal inflammation was determined by IL-1β, TNFα and IL-17 A expression. TLR4, MyD88, pp38 MAPK, and endoplasmic reticulum stress (ERS)-related molecules (Bip, p-IRE1α, sXBP1, p-eIF2α, ATF6) were measured by immunohistochemistry and WB. RESULTS Quercetin intervention attenuated pancreatic and ileal pathological damages in ANP (P < 0.05), ameliorated intestinal barrier disruption and inflammation (P < 0.05). Meantime, QE significantly suppressed intestinal TLR4/MyD88/p38 MAPK pathway and ERS activation. CONCLUSIONS Quercetin plays a protective role against intestinal barrier disruption and inflammation in ANP, probably partly by inhibiting TLR4/MyD88/p38 MAPK and ERS activation.
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Affiliation(s)
- Zheng Junyuan
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Xu Hui
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Huang Chunlan
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Fan Junjie
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Mei Qixiang
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Lu Yingying
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Lou Lihong
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
| | - Wang Xingpeng
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
| | - Zeng Yue
- Shanghai Key Laboratory of Pancreatic Disease & Department of Gastroenterology, Shanghai General Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
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Liu L, Steinle JJ. Loss of TLR4 in mouse Müller cells inhibits both MyD88-dependent and -independent signaling. PLoS One 2017; 12:e0190253. [PMID: 29287085 PMCID: PMC5747480 DOI: 10.1371/journal.pone.0190253] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 12/11/2017] [Indexed: 11/18/2022] Open
Abstract
Müller cells are key to metabolic and ionic regulation in the retina. They also produce a number of inflammatory mediators and are significantly affected in diabetic retinopathy. To investigate the role of toll-like receptor 4 (TLR4) in retinal Müller cells, we crossed TLR4 floxed with PDGFRα-Cre mice to eliminate TLR4 in retinal Müller cells. We performed Western blotting and ELISA analyses to determine whether loss of TLR4 affected myeloid differentiation primary response protein (MyD88)-dependent or –independent signaling, leading to reduced levels of tumor necrosis factor alpha (TNFα) and interleukin 1 beta (IL1β) in whole retinal lysates from the TLR4 floxed and TLR4-PDGFRα-Cre mice. Data show that TLR4-PDGFRα-Cre mice have reduced levels of both the MyD88-dependent and -independent signaling pathways. These studies confirm successful development of a Müller cell-specific TLR4 knockout mouse colony. These mice have reduced MyD88-dependent and –independent signaling pathway proteins, as well as reduced TNFα and IL1β levels. These mice can be used to dissect TLR4 signaling in disorders affecting retinal Müller cells.
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Affiliation(s)
- Li Liu
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Jena J. Steinle
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, United States of America
- Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, United States of America
- * E-mail:
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