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Hoffet MS, Tomov NS, Hupp S, Mitchell TJ, Iliev AI. Glucose and Oxygen Levels Modulate the Pore-Forming Effects of Cholesterol-Dependent Cytolysin Pneumolysin from Streptococcus pneumoniae. Toxins (Basel) 2024; 16:232. [PMID: 38922127 PMCID: PMC11209487 DOI: 10.3390/toxins16060232] [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: 03/08/2024] [Revised: 05/08/2024] [Accepted: 05/16/2024] [Indexed: 06/27/2024] Open
Abstract
A major Streptococcus pneumoniae pathogenic factor is the cholesterol-dependent cytolysin pneumolysin, binding membrane cholesterol and producing permanent lytic or transient pores. During brain infections, vascular damage with variable ischemia occurs. The role of ischemia on pneumolysin's pore-forming capacity remains unknown. In acute brain slice cultures and primary cultured glia, we studied acute toxin lysis (via propidium iodide staining and LDH release) and transient pore formation (by analyzing increases in the intracellular calcium). We analyzed normal peripheral tissue glucose conditions (80 mg%), normal brain glucose levels (20 mg%), and brain hypoglycemic conditions (3 mg%), in combinations either with normoxia (8% oxygen) or hypoxia (2% oxygen). At 80 mg% glucose, hypoxia enhanced cytolysis via pneumolysin. At 20 mg% glucose, hypoxia did not affect cell lysis, but impaired calcium restoration after non-lytic pore formation. Only at 3 mg% glucose, during normoxia, did pneumolysin produce stronger lysis. In hypoglycemic (3 mg% glucose) conditions, pneumolysin caused a milder calcium increase, but restoration was missing. Microglia bound more pneumolysin than astrocytes and demonstrated generally stronger calcium elevation. Thus, our work demonstrated that the toxin pore-forming capacity in cells continuously diminishes when oxygen is reduced, overlapping with a continuously reduced ability of cells to maintain homeostasis of the calcium influx once oxygen and glucose are reduced.
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Affiliation(s)
- Michelle Salomé Hoffet
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012 Bern, Switzerland; (M.S.H.); (N.S.T.); (S.H.)
| | - Nikola S. Tomov
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012 Bern, Switzerland; (M.S.H.); (N.S.T.); (S.H.)
| | - Sabrina Hupp
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012 Bern, Switzerland; (M.S.H.); (N.S.T.); (S.H.)
| | - Timothy J. Mitchell
- School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK;
| | - Asparouh I. Iliev
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012 Bern, Switzerland; (M.S.H.); (N.S.T.); (S.H.)
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2
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Wilson JA, Lin ZJ, Rodriguez I, Ta T, Martz L, Fico D, Johnson SS, Gorden JD, Shelton KL, King LB. Synthesis, characterization, and antimicrobial activity of lipophilic
N
,
N
′‐bis‐substituted triazolium salts. J Heterocycl Chem 2021. [DOI: 10.1002/jhet.4403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Julie A. Wilson
- Department of Biology Columbus State University Columbus Georgia USA
| | - Zi Jie Lin
- Department of Chemistry Columbus State University Columbus Georgia USA
| | | | - Thong Ta
- Department of Chemistry Columbus State University Columbus Georgia USA
| | - Luke Martz
- Department of Chemistry Columbus State University Columbus Georgia USA
| | - Dominic Fico
- Department of Chemistry Columbus State University Columbus Georgia USA
| | | | - John D. Gorden
- Department of Chemistry Texas Tech University Lubbock Texas USA
| | - Kerri L. Shelton
- Department of Chemistry Columbus State University Columbus Georgia USA
| | - Lauren B. King
- Department of Biology Columbus State University Columbus Georgia USA
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3
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Livingston ET, Mursalin MH, Callegan MC. A Pyrrhic Victory: The PMN Response to Ocular Bacterial Infections. Microorganisms 2019; 7:microorganisms7110537. [PMID: 31703354 PMCID: PMC6920826 DOI: 10.3390/microorganisms7110537] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/03/2019] [Accepted: 11/05/2019] [Indexed: 12/21/2022] Open
Abstract
Some tissues of the eye are susceptible to damage due to their exposure to the outside environment and inability to regenerate. Immune privilege, although beneficial to the eye in terms of homeostasis and protection, can be harmful when breached or when an aberrant response occurs in the face of challenge. In this review, we highlight the role of the PMN (polymorphonuclear leukocyte) in different bacterial ocular infections that invade the immune privileged eye at the anterior and posterior segments: keratitis, conjunctivitis, uveitis, and endophthalmitis. Interestingly, the PMN response from the host seems to be necessary for pathogen clearance in ocular disease, but the inflammatory response can also be detrimental to vision retention. This “Pyrrhic Victory” scenario is explored in each type of ocular infection, with details on PMN recruitment and response at the site of ocular infection. In addition, we emphasize the differences in PMN responses between each ocular disease and its most common corresponding bacterial pathogen. The in vitro and animal models used to identify PMN responses, such as recruitment, phagocytosis, degranulation, and NETosis, are also outlined in each ocular infection. This detailed study of the ocular acute immune response to infection could provide novel therapeutic strategies for blinding diseases, provide more general information on ocular PMN responses, and reveal areas of bacterial ocular infection research that lack PMN response studies.
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Affiliation(s)
- Erin T. Livingston
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (E.T.L.); (M.H.M.)
| | - Md Huzzatul Mursalin
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (E.T.L.); (M.H.M.)
| | - Michelle C. Callegan
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (E.T.L.); (M.H.M.)
- Department of Ophthalmology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Oklahoma Center for Neuroscience, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Dean McGee Eye Institute, Oklahoma City, OK 73104, USA
- Correspondence:
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4
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Benton AH, Jackson MD, Wong SM, Dees JL, Akerley BJ, Marquart ME. A Transcriptional Activator of Ascorbic Acid Transport in Streptococcus pneumoniae Is Required for Optimal Growth in Endophthalmitis in a Strain-Dependent Manner. Microorganisms 2019; 7:microorganisms7090290. [PMID: 31450542 PMCID: PMC6780617 DOI: 10.3390/microorganisms7090290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/18/2019] [Accepted: 08/21/2019] [Indexed: 11/16/2022] Open
Abstract
Streptococcus pneumoniae is among the top causes of bacterial endophthalmitis, an infectious disease of the intraocular fluids. The mechanisms by which S. pneumoniae grows and thrives in the intraocular cavity are not well understood. We used a bacterial genome-wide assessment tool (transposon insertion site sequencing) to determine genes essential for S. pneumoniae growth in vitreous humor. The results indicated that an ascorbic acid (AA) transport system subunit was important for growth. We created an isogenic gene deletion mutant of the AA transcriptional activator, ulaR2, in 2 strains of S. pneumoniae. Growth curve analysis indicated that ulaR2 deletion caused attenuated growth in vitro for both strains. However, in vivo vitreous humor infection in rabbits with either strain determined that ulaR2 was necessary for growth in one strain but not the other. These results demonstrate that ulaR2 may be important for fitness during S. pneumoniae endophthalmitis depending on the background of the strain.
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Affiliation(s)
- Angela H Benton
- University of Mississippi Medical Center, Jackson, MS 39216, USA
- Current affiliation: Virginia Tech, Blacksburg, VA 24061, USA
| | | | - Sandy M Wong
- University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Justine L Dees
- University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Brian J Akerley
- University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Mary E Marquart
- University of Mississippi Medical Center, Jackson, MS 39216, USA.
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5
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Abstract
Endophthalmitis is a blinding consequence of bacterial invasion of the interior of the eye. Because of increases in the numbers of ocular surgeries and intraocular injections, the incidence of endophthalmitis is steadily increasing. Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, and Bacillus cereus are leading causes of infection following ocular procedures and trauma and are increasingly more difficult to treat due to multidrug resistance. Each of these pathogens produces pore-forming toxins that contribute to the pathogenesis of endophthalmitis. Treatment of these infections with antibiotics alone is insufficient to prevent damage to the retina and vision loss. Therefore, novel therapeutics are needed that include agents that neutralize bacterial pore-forming toxins. Here, we demonstrate that biomimetic nanosponges neutralize pore-forming toxins from these ocular pathogens and aid in preserving retinal function. Nanosponges may represent a new form of adjunct antitoxin therapy for serious potentially blinding intraocular infections. Intraocular infections are prevalent after traumatic injuries or after common ocular surgeries. Infections cause inflammation that can damage the retina and architecture of the eye, often resulting in poor visual outcomes. Severe cases may result in blindness or require enucleation of the eye. Treatments for intraocular infections include intravitreal antibiotics and corticosteroids or surgical vitrectomy in serious cases. The increase in multidrug-resistant infections calls for novel treatment options. In the present study, a biomimetic erythrocyte-derived nanosponge was tested for the ability to neutralize pore-forming toxins from the most frequent Gram-positive bacterial causes of intraocular infections (Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, and Bacillus cereus). Nanosponge pretreatment of supernatants reduced hemolytic activity in vitro. In a murine sterile endophthalmitis model, nanosponge pretreatment of injected supernatants resulted in greater retinal function and less ocular pathology compared to that in eyes injected with untreated supernatants from all pathogens except methicillin-resistant S. aureus. In a murine bacterial endophthalmitis model, treatment with gatifloxacin and gatifloxacin-nanosponges reduced intraocular bacterial burdens, except in the case of methicillin-sensitive S. aureus. For all pathogens, eyes in both treatment groups showed decreased ocular pathology and inflammation. Overall, reductions in retinal function loss afforded by gatifloxacin-nanosponge treatment were significant for E. faecalis, S. pneumoniae, and methicillin-resistant S. aureus but not for B. cereus and methicillin-sensitive S. aureus. These results suggest that clinical improvements in intraocular infections following nanosponge treatment were dependent on the complexity and types of toxins produced. Nanosponges might serve as an adjunctive therapy for the treatment of ocular infections. IMPORTANCE Endophthalmitis is a blinding consequence of bacterial invasion of the interior of the eye. Because of increases in the numbers of ocular surgeries and intraocular injections, the incidence of endophthalmitis is steadily increasing. Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, and Bacillus cereus are leading causes of infection following ocular procedures and trauma and are increasingly more difficult to treat due to multidrug resistance. Each of these pathogens produces pore-forming toxins that contribute to the pathogenesis of endophthalmitis. Treatment of these infections with antibiotics alone is insufficient to prevent damage to the retina and vision loss. Therefore, novel therapeutics are needed that include agents that neutralize bacterial pore-forming toxins. Here, we demonstrate that biomimetic nanosponges neutralize pore-forming toxins from these ocular pathogens and aid in preserving retinal function. Nanosponges may represent a new form of adjunct antitoxin therapy for serious potentially blinding intraocular infections.
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6
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Riegler AN, Brissac T, Gonzalez-Juarbe N, Orihuela CJ. Necroptotic Cell Death Promotes Adaptive Immunity Against Colonizing Pneumococci. Front Immunol 2019; 10:615. [PMID: 31019504 PMCID: PMC6459137 DOI: 10.3389/fimmu.2019.00615] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/08/2019] [Indexed: 12/12/2022] Open
Abstract
Pore-forming toxin (PFT) induced necroptosis exacerbates pulmonary injury during bacterial pneumonia. However, its role during asymptomatic nasopharyngeal colonization and toward the development of protective immunity was unknown. Using a mouse model of Streptococcus pneumoniae (Spn) asymptomatic colonization, we determined that nasopharyngeal epithelial cells (nEC) died of pneumolysin (Ply)-dependent necroptosis. Mice deficient in MLKL, the necroptosis effector, or challenged with Ply-deficient Spn showed less nEC sloughing, increased neutrophil infiltration, and altered IL-1α, IL-33, CXCL2, IL-17, and IL-6 levels in nasal lavage fluid (NALF). Activated MLKL correlated with increased presence of CD11c+ antigen presenting cells in Spn-associated submucosa. Colonized MLKL KO mice and wildtype mice colonized with Ply-deficient Spn produced less antibody against the bacterial surface protein PspA, were delayed in bacterial clearance, and were more susceptible to a lethal secondary Spn challenge. We conclude that PFT-induced necroptosis is instrumental in the natural development of protective immunity against opportunistic PFT-producing bacterial pathogens.
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Affiliation(s)
- Ashleigh Nichole Riegler
- Department of Microbiology, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Terry Brissac
- Department of Microbiology, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Norberto Gonzalez-Juarbe
- Department of Microbiology, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Carlos J Orihuela
- Department of Microbiology, The University of Alabama at Birmingham, Birmingham, AL, United States
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7
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Simonett JM, Igelman A, Taylor SC, Campbell JP, Hwang TS, Lin P, Lauer AK, Flaxel CJ. Culture-Proven Endophthalmitis After Intravitreal Injection: A 10-Year Analysis. Ophthalmic Surg Lasers Imaging Retina 2019; 50:33-38. [PMID: 30640393 DOI: 10.3928/23258160-20181212-05] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 11/02/2018] [Indexed: 11/20/2022]
Abstract
BACKGROUND AND OBJECTIVE To report on the microbiology, management, and visual outcomes of intravitreal injection (IVI)-associated, culture-proven endophthalmitis. PATIENTS AND METHODS All patients seen at a tertiary referral center with culture-proven endophthalmitis associated with an IVI between June 2007 and July 2017 were included in this retrospective analysis. RESULTS Thirty-five patients with culture-positive endophthalmitis following IVI were identified. All gram-positive organisms (34 of 35) were susceptible to vancomycin. Cases due to pathogens associated with oral or respiratory flora were common (31.4%, n = 11), presented earlier (2.0 days vs. 4.6 days, P < .001), were more likely to undergo pars plana vitrectomy (81.8% vs. 25.0%, P = .002) and had worse visual acuity outcomes. CONCLUSION IVI-associated endophthalmitis pathogens and anti-microbial susceptibilities in the Pacific Northwest are similar to those reported from other geographic locations. Bacteria associated with the oral and respiratory flora are common isolates that result in a more aggressive course and worse visual outcomes. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:33-38.].
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8
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The Role of Pneumococcal Virulence Factors in Ocular Infectious Diseases. Interdiscip Perspect Infect Dis 2018; 2018:2525173. [PMID: 30538741 PMCID: PMC6257906 DOI: 10.1155/2018/2525173] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 11/07/2018] [Indexed: 12/24/2022] Open
Abstract
Streptococcus pneumoniae is a gram-positive, facultatively anaerobic pathogen that can cause severe infections such as pneumonia, meningitis, septicemia, and middle ear infections. It is also one of the top pathogens contributing to bacterial keratitis and conjunctivitis. Though two pneumococcal vaccines exist for the prevention of nonocular diseases, they do little to fully prevent ocular infections. This pathogen has several virulence factors that wreak havoc on the conjunctiva, cornea, and intraocular system. Polysaccharide capsule aids in the evasion of host complement system. Pneumolysin (PLY) is a cholesterol-dependent cytolysin that acts as pore-forming toxin. Neuraminidases assist in adherence and colonization by exposing cell surface receptors to the pneumococcus. Zinc metalloproteinases contribute to evasion of the immune system and disease severity. The main purpose of this review is to consolidate the multiple studies that have been conducted on several pneumococcal virulence factors and the role each plays in conjunctivitis, keratitis, and endophthalmitis.
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9
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Pan Q, Liu Y, Wang R, Chen T, Yang Z, Deng Y, Zhao Z, Hu X, Chen X, Wei W, Zhang Z, Wang Y, Zheng J, Ke Z. Treatment of Bacillus cereus endophthalmitis with endoscopy-assisted vitrectomy. Medicine (Baltimore) 2017; 96:e8701. [PMID: 29390262 PMCID: PMC5815674 DOI: 10.1097/md.0000000000008701] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
To evaluate the use of endoscopy-assisted vitrectomy in patients with sight-threatening Bacillus cereus endophthalmitis.A retrospective analysis was conducted in 15 eyes with Bacillus cereus endophthalmitis. Patients were divided into 2 groups: endoscopy-assisted vitrectomy (5 eyes) and conventional vitrectomy (10 eyes). The following clinical data were recorded and analyzed: sex, age, latent period, symptom duration, follow-up time, visual acuity pre- and postsurgery, recurrence of endophthalmitis, incidence of phithisis bulbi, and incidence of enucleation.In the conventional vitrectomy group, postoperative visual acuity ranged from no light perception in 5 patients (50%), light perception in 3 patients (30%), 20/1000 in 1 patient (10%), and 20/50 in 1 patient (10%). In the endoscopy-assisted vitrectomy group, postoperative visual acuity ranged from no light perception in 2 patients (40%), light perception in 1 patient (20%), and hand movements in 2 patients (40%). There was no statistically significant difference between the 2 groups in terms of the final postoperative visual acuity (F = 0.006, P = .937). There is no difference between the 2 groups in terms of the incidence of enucleation. The median symptom duration was 4 hours (range: 2-6 hours) in the conventional group and 9 hours (range: 7-11 hours) in the endoscopy-assisted vitrectomy group. The difference in the symptom duration between the 2 groups was statistically significant (P = .002).There is no statistical significant difference between the 2 groups in terms of visual acuity and incidence of enucleation. Therefore, endoscopy-assisted vitrectomy can be considered as an alternative treatment for treatment of B cereus endophthalmitis particularly for cases when symptom duration was more than 6 hours.
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Affiliation(s)
- Qintuo Pan
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yanhua Liu
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Ruixi Wang
- Australian College Of Optometry Melbourne, Victoria, Australia
| | - Tianyu Chen
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhengwei Yang
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yuxuan Deng
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhenquan Zhao
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xuting Hu
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiaomeng Chen
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Wenlong Wei
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zongduan Zhang
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yuqin Wang
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jingwei Zheng
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhisheng Ke
- The Eye Hospital of Wenzhou Medical University, Wenzhou, China
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10
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Nam KY, Lee SJ, Kim JY. Systemic Moxifloxacin in Streptococcus viridans Endophthalmitis. Ocul Immunol Inflamm 2017; 27:155-161. [DOI: 10.1080/09273948.2017.1353103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Ki Yup Nam
- Department of Ophthalmology, Chungnam National University College of Medicine, Daejeon, Republic of Korea
- Department of Ophthalmology, Kosin University College of Medicine, Busan, Republic of Korea
| | - Sang Joon Lee
- Department of Ophthalmology, Kosin University College of Medicine, Busan, Republic of Korea
- Institute for Medicine, Kosin University, Busan, Republic of Korea
| | - Jung Yeul Kim
- Department of Ophthalmology, Chungnam National University College of Medicine, Daejeon, Republic of Korea
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Grayson KM, Blevins LK, Oliver MB, Ornelles DA, Swords WE, Alexander-Miller MA. Activation-dependent modulation of Streptococcus pneumoniae-mediated death in human lymphocytes. Pathog Dis 2017; 75:2966467. [PMID: 28158464 DOI: 10.1093/femspd/ftx008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 01/30/2017] [Indexed: 01/27/2023] Open
Abstract
Streptococcus pneumoniae (Spn) is a leading cause of community-acquired pneumonia, with infants and the elderly exhibiting significant susceptibility to the development of severe disease. A growing body of evidence supports the ability of Spn to negatively regulate the host response to infection, e.g. the capacity to induce death in numerous cell types. However, our understanding of the ability of Spn to directly impact lymphocytes remains limited. In this study, we tested the hypothesis that lymphocyte type and activation state influences the susceptibility to pneumococcus-mediated death. We show that in the resting state, CD4+ T cells exhibit a modestly increased susceptibility to Spn-induced death compared to CD8+ T cells or NK cells. In the presence of activating stimuli, the situation most reflective of what would occur in vivo during infection, all subsets demonstrated a significant increase in sensitivity to Spn-mediated death. Importantly, the activated subsets diverged dramatically in susceptibility with natural killer cells exhibiting an 8.6-fold greater sensitivity to pneumococcal components compared to the T-cell subsets. These results significantly expand our understanding of the capacity for pneumococcus to negatively regulate lymphocytes.
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12
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Astley RA, Coburn PS, Parkunan SM, Callegan MC. Modeling intraocular bacterial infections. Prog Retin Eye Res 2016; 54:30-48. [PMID: 27154427 PMCID: PMC4992594 DOI: 10.1016/j.preteyeres.2016.04.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 04/15/2016] [Accepted: 04/24/2016] [Indexed: 12/31/2022]
Abstract
Bacterial endophthalmitis is an infection and inflammation of the posterior segment of the eye which can result in significant loss of visual acuity. Even with prompt antibiotic, anti-inflammatory and surgical intervention, vision and even the eye itself may be lost. For the past century, experimental animal models have been used to examine various aspects of the pathogenesis and pathophysiology of bacterial endophthalmitis, to further the development of anti-inflammatory treatment strategies, and to evaluate the pharmacokinetics and efficacies of antibiotics. Experimental models allow independent control of many parameters of infection and facilitate systematic examination of infection outcomes. While no single animal model perfectly reproduces the human pathology of bacterial endophthalmitis, investigators have successfully used these models to understand the infectious process and the host response, and have provided new information regarding therapeutic options for the treatment of bacterial endophthalmitis. This review highlights experimental animal models of endophthalmitis and correlates this information with the clinical setting. The goal is to identify knowledge gaps that may be addressed in future experimental and clinical studies focused on improvements in the therapeutic preservation of vision during and after this disease.
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Affiliation(s)
- Roger A Astley
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Phillip S Coburn
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Salai Madhumathi Parkunan
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Michelle C Callegan
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean McGee Eye Institute, Oklahoma City, OK, USA.
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13
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Thornton JA, Tullos NA, Sanders ME, Ridout G, Wang YD, Taylor SD, McDaniel LS, Marquart ME. Differential bacterial gene expression during experimental pneumococcal endophthalmitis. Ophthalmic Res 2015; 53:149-61. [PMID: 25791614 DOI: 10.1159/000371713] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/18/2014] [Indexed: 12/22/2022]
Abstract
Streptococcus pneumoniae (pneumococcus) is a potential cause of bacterial endophthalmitis in humans that can result in ocular morbidity. We sought to identify pneumococcal genes that are differentially expressed during growth in the vitreous humor of the eye in an experimental endophthalmitis model. Microarray analysis was used to identify genes that were differentially expressed when pneumococci replicated in the vitreous of rabbit eyes as compared with bacteria grown in vitro in Todd Hewitt medium. Array results were verified by quantitative real-time PCR analysis of representative genes. Select genes potentially playing a role in virulence during endophthalmitis were deleted, and mutants were tested for reduced eye pathogenesis and altered adhesion to host cells. Array analysis identified 134 genes that were differentially expressed during endophthalmitis; 112 genes demonstrated increased expression during growth in the eye whereas 22 were downregulated. Real-time analysis verified increased expression of neuraminidase A (NanA; SP1693), neuraminidase B (NanB; SP1687) and serine protease (SP1954), and decreased expression of RlrA (SP0461) and choline transporter (SP1861). Mutation of NanA and NanB had no major effect on pathogenesis. Loss of SP1954 led to increased adherence to host cells. S. pneumoniae enhances and represses the expression of a variety of genes during endophthalmitis. While some of these genes reflect changes in metabolic requirements, some appear to play a role in immune evasion and pathogenesis in the eye.
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Affiliation(s)
- Justin A Thornton
- Department of Biological Sciences, Mississippi State University, Starkville, Miss., USA
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14
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Parkunan SM, Astley R, Callegan MC. Role of TLR5 and flagella in bacillus intraocular infection. PLoS One 2014; 9:e100543. [PMID: 24959742 PMCID: PMC4068998 DOI: 10.1371/journal.pone.0100543] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 05/28/2014] [Indexed: 01/30/2023] Open
Abstract
B. cereus possesses flagella which allow the organism to migrate within the eye during a blinding form of intraocular infection called endophthalmitis. Because flagella is a ligand for Toll-like receptor 5 (TLR5), we hypothesized that TLR5 contributed to endophthalmitis pathogenesis. Endophthalmitis was induced in C57BL/6J and TLR5−/− mice by injecting 100 CFU of B. cereus into the mid-vitreous. Eyes were analyzed for intraocular bacterial growth, retinal function, and inflammation by published methods. Purified B. cereus flagellin was also injected into the mid-vitreous of wild type C57BL/6J mice and inflammation was analyzed. TLR5 activation by B. cereus flagellin was also analyzed in vitro. B. cereus grew rapidly and at similar rates in infected eyes of C57BL/6J and TLR5−/− mice. A significant loss in retinal function in both groups of mice was observed at 8 and 12 hours postinfection. Retinal architecture disruption and acute inflammation (neutrophil infiltration and proinflammatory cytokine concentrations) increased and were significant at 8 and 12 hours postinfection. Acute inflammation was comparable in TLR5−/− and C57BL/6J mice. Physiological concentrations of purified B. cereus flagellin caused significant inflammation in C57BL/6J mouse eyes, but not to the extent of that observed during active infection. Purified B. cereus flagellin was a weak agonist for TLR5 in vitro. These results demonstrated that the absence of TLR5 did not have a significant effect on the evolution of B. cereus endophthalmitis. This disparity may be due to sequence differences in important TLR5 binding domains in B. cereus flagellin or the lack of flagellin monomers in the eye to activate TLR5 during infection. Taken together, these results suggest a limited role for flagellin/TLR5 interactions in B. cereus endophthalmitis. Based on this and previous data, the importance of flagella in this disease lies in its contribution to the motility of the organism within the eye during infection.
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Affiliation(s)
- Salai Madhumathi Parkunan
- Departments of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Roger Astley
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Michelle C. Callegan
- Departments of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- Dean A. McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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15
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Navarro-Noya Y, Hernández-Rodríguez C, Zenteno JC, Buentello-Volante B, Cancino-Díaz ME, Jan-Roblero J, Cancino-Díaz JC. 16S rRNA gene-based identification of bacteria in postoperative endophthalmitis by PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) fingerprinting. Braz J Microbiol 2012; 43:283-7. [PMID: 24031830 PMCID: PMC3768976 DOI: 10.1590/s1517-838220120001000033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 08/30/2011] [Indexed: 11/21/2022] Open
Abstract
Conventional microbiological culture techniques are frequently insufficient to confirm endophthalmitis clinical cases which could require urgent medical attention because it could lead to permanent vision loss. We are proposing PCR-DGGE and 16S rRNA gene libraries as an alternative to improve the detection and identification rate of bacterial species from endophthalmitis cases.
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Affiliation(s)
- Yendi Navarro-Noya
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas-IPN , Mexico, D.F. Mexico
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16
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Sanders ME, Tullos NA, Taylor SD, Norcross EW, King LB, Tolo I, Marquart ME. Moxifloxacin and cholesterol combined treatment of pneumococcal keratitis. Curr Eye Res 2011; 35:1142-7. [PMID: 21121810 DOI: 10.3109/02713683.2010.512114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Compare the efficacy of treatment of pneumococcal keratitis with cholesterol, moxifloxacin, or a mixture of the two (moxifloxacin/cholesterol). MATERIALS AND METHODS New Zealand white rabbits were injected intrastromally with 10(6) colony-forming units (CFU) of a clinical keratitis strain of Streptococcus pneumoniae. Eyes were examined before and after treatment of topical drops every 2 hr from 25 to 47 hr post-infection (PI). Corneas were harvested to quantitate bacterial CFU, and myeloperoxidase (MPO) activity was measured at 48 hr PI. Eyes were extracted for histology. Minimal inhibitory concentrations (MICs) were determined for each compound. RESULTS Eyes treated with moxifloxacin/cholesterol had a significantly lower mean slit lamp examination (SLE) score than eyes treated with phosphate-buffered saline (PBS), moxifloxacin alone, or cholesterol alone (P ≤ 0.02). A significantly lower log(10) CFU was recovered from corneas treated with moxifloxacin/cholesterol and moxifloxacin alone as compared to corneas of eyes treated with PBS or cholesterol alone (P < 0.01). At 48 hr PI, significantly lower MPO activity was quantitated from eyes treated with moxifloxacin/cholesterol as compared to eyes treated with cholesterol or moxifloxacin alone (P ≤ 0.046). Eyes treated with moxifloxacin/cholesterol had fewer immune cells and less corneal destruction than eyes from all other treatment groups. The MIC for moxifloxacin alone was 0.125 μg/mL, and cholesterol alone was unable to inhibit growth at any of the concentrations tested. The MIC for moxifloxacin when combined with 1% cholesterol was 0.0625 μg/mL. CONCLUSIONS Treatment with a mixture of moxifloxacin and cholesterol significantly lowers the severity of infection caused by pneumococcal keratitis as compared to treatment with moxifloxacin alone, cholesterol alone, or PBS. This treatment mixture eradicates the bacteria in the cornea, unlike treatment with PBS or cholesterol alone. Using cholesterol with moxifloxacin as a treatment for bacterial keratitis could help lower the clinical severity of the infection.
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Affiliation(s)
- Melissa E Sanders
- Department of Microbiology, University of Mississippi Medical Center, Jackson, Mississippi, USA
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