1
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Shahzad AM, Lu W, Dey S, Bhattarai P, Gaikwad AV, Jaffar J, Westall G, Sutherland D, Singhera GK, Hackett TL, Eapen MS, Sohal SS. Platelet Activating Factor Receptor and Intercellular Adhesion Molecule-1 Expression Increases in the Small Airway Epithelium and Parenchyma of Patients with Idiopathic Pulmonary Fibrosis: Implications for Microbial Pathogenesis. J Clin Med 2024; 13:2126. [PMID: 38610892 PMCID: PMC11012432 DOI: 10.3390/jcm13072126] [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: 03/05/2024] [Revised: 03/25/2024] [Accepted: 04/04/2024] [Indexed: 04/14/2024] Open
Abstract
Background: Idiopathic pulmonary fibrosis (IPF) is an irreversible lung fibrotic disorder of unknown cause. It has been reported that bacterial and viral co-infections exacerbate disease pathogenesis. These pathogens use adhesion molecules such as platelet activating factor receptor (PAFR) and intercellular adhesion molecule-1 (ICAM-1) to gain cellular entry, causing infections. Methods: Immunohistochemical staining was carried out for lung resections from IPF patients (n = 11) and normal controls (n = 12). The quantification of PAFR and ICAM-1 expression is presented as a percentage in the small airway epithelium. Also, type 2 pneumocytes and alveolar macrophages were counted as cells per mm2 of the parenchymal area and presented as a percentage. All image analysis was done using Image Pro Plus 7.0 software. Results: PAFR expression significantly increased in the small airway epithelium (p < 0.0001), type 2 pneumocytes (p < 0.0001) and alveolar macrophages (p < 0.0001) compared to normal controls. Similar trend was observed for ICAM-1 expression in the small airway epithelium (p < 0.0001), type 2 pneumocytes (p < 0.0001) and alveolar macrophages (p < 0.0001) compared to normal controls. Furthermore, the proportion of positively expressed type 2 pneumocytes and alveolar macrophages was higher in IPF than in normal control. Conclusions: This is the first study to show PAFR and ICAM-1 expression in small airway epithelium, type 2 pneumocytes and alveolar macrophages in IPF. These findings could help intervene microbial impact and facilitate management of disease pathogenesis.
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Affiliation(s)
- Affan Mahmood Shahzad
- Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia
- Medical School, Oceania University of Medicine, Apia WS1330, Samoa
| | - Wenying Lu
- Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia
- National Health and Medical Research Council (NHMRC) Centre of Research Excellence (CRE) in Pulmonary Fibrosis, Respiratory Medicine and Sleep Unit, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
| | - Surajit Dey
- Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia
| | - Prem Bhattarai
- Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia
| | - Archana Vijay Gaikwad
- Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia
- National Health and Medical Research Council (NHMRC) Centre of Research Excellence (CRE) in Pulmonary Fibrosis, Respiratory Medicine and Sleep Unit, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
| | - Jade Jaffar
- Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, VIC 3004, Australia
- Department of Immunology and Pathology, Monash University, Melbourne, VIC 3800, Australia
| | - Glen Westall
- Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, VIC 3004, Australia
- Department of Immunology and Pathology, Monash University, Melbourne, VIC 3800, Australia
| | - Darren Sutherland
- Department of Anaesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for Heart Lung Innovation, St. Paul’s Hospital, Vancouver, BC V6Z 1Y6, Canada
| | - Gurpreet Kaur Singhera
- Department of Anaesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for Heart Lung Innovation, St. Paul’s Hospital, Vancouver, BC V6Z 1Y6, Canada
| | - Tillie-Louise Hackett
- Department of Anaesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for Heart Lung Innovation, St. Paul’s Hospital, Vancouver, BC V6Z 1Y6, Canada
| | - Mathew Suji Eapen
- Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia
- National Health and Medical Research Council (NHMRC) Centre of Research Excellence (CRE) in Pulmonary Fibrosis, Respiratory Medicine and Sleep Unit, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
| | - Sukhwinder Singh Sohal
- Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia
- National Health and Medical Research Council (NHMRC) Centre of Research Excellence (CRE) in Pulmonary Fibrosis, Respiratory Medicine and Sleep Unit, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
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2
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Shi T, Wang J, Dong J, Hu P, Guo Q. Periodontopathogens Porphyromonas gingivalis and Fusobacterium nucleatum and Their Roles in the Progression of Respiratory Diseases. Pathogens 2023; 12:1110. [PMID: 37764918 PMCID: PMC10535846 DOI: 10.3390/pathogens12091110] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/18/2023] [Accepted: 08/28/2023] [Indexed: 09/29/2023] Open
Abstract
The intricate interplay between oral microbiota and the human host extends beyond the confines of the oral cavity, profoundly impacting the general health status. Both periodontal diseases and respiratory diseases show high prevalence worldwide and have a marked influence on the quality of life for the patients. Accumulating studies are establishing a compelling association between periodontal diseases and respiratory diseases. Here, in this review, we specifically focus on the key periodontal pathogenic bacteria Porphyromonas gingivalis and Fusobacterium nucleatum and dissect their roles in the onset and course of respiratory diseases, mainly pneumonia, chronic obstructive pulmonary disease, lung cancer, and asthma. The mechanistic underpinnings and molecular processes on how P. gingivalis and F. nucleatum contribute to the progression of related respiratory diseases are further summarized and analyzed, including: induction of mucus hypersecretion and chronic airway inflammation; cytotoxic effects to disrupt the morphology and function of respiratory epithelial cells; synergistic pathogenic effects with respiratory pathogens like Streptococcus pneumoniae and Pseudomonas aeruginosa. By delving into the complex relationship to periodontal diseases and periodontopathogens, this review helps unearth novel insights into the etiopathogenesis of respiratory diseases and inspires the development of potential therapeutic avenues and preventive strategies.
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Affiliation(s)
- Tao Shi
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jiale Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jiajia Dong
- Department of Pulmonary and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu 610041, China
- State Key Laboratory of Respiratory Health and Multimorbidity, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Pingyue Hu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Qiang Guo
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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3
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Zhang Y, Jen FEC, Fox KL, Edwards JL, Jennings MP. The biosynthesis and role of phosphorylcholine in pathogenic and nonpathogenic bacteria. Trends Microbiol 2023; 31:692-706. [PMID: 36863982 PMCID: PMC10272106 DOI: 10.1016/j.tim.2023.01.006] [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: 09/02/2021] [Revised: 01/18/2023] [Accepted: 01/23/2023] [Indexed: 03/03/2023]
Abstract
Phosphorylcholine (ChoP) can be found in all life forms. Although this molecule was first thought to be uncommon in bacteria, it is now appreciated that many bacteria express ChoP on their surface. ChoP is usually attached to a glycan structure, but in some cases, it is added as a post-translational modification to proteins. Recent findings have demonstrated the role of ChoP modification and phase variation (ON/OFF switching) in bacterial pathogenesis. However, the mechanisms of ChoP synthesis are still unclear in some bacteria. Here, we review the literature and examine the recent developments in ChoP-modified proteins and glycolipids and of ChoP biosynthetic pathways. We discuss how the well-studied Lic1 pathway exclusively mediates ChoP attachment to glycans but not to proteins. Finally, we provide a review of the role of ChoP in bacterial pathobiology and the role of ChoP in modulating the immune response.
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Affiliation(s)
- Yuan Zhang
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD 4222, Australia
| | - Freda E-C Jen
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD 4222, Australia
| | - Kate L Fox
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia
| | - Jennifer L Edwards
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA; Department of Pediatrics, The Ohio State University, Columbus, OH 43210, USA
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD 4222, Australia.
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4
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Barichello T, Rocha Catalão CH, Rohlwink UK, van der Kuip M, Zaharie D, Solomons RS, van Toorn R, Tutu van Furth M, Hasbun R, Iovino F, Namale VS. Bacterial meningitis in Africa. Front Neurol 2023; 14:822575. [PMID: 36864913 PMCID: PMC9972001 DOI: 10.3389/fneur.2023.822575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 01/18/2023] [Indexed: 02/16/2023] Open
Abstract
Bacterial meningitis differs globally, and the incidence and case fatality rates vary by region, country, pathogen, and age group; being a life-threatening disease with a high case fatality rate and long-term complications in low-income countries. Africa has the most significant prevalence of bacterial meningitis illness, and the outbreaks typically vary with the season and the geographic location, with a high incidence in the meningitis belt of the sub-Saharan area from Senegal to Ethiopia. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are the main etiological agents of bacterial meningitis in adults and children above the age of one. Streptococcus agalactiae (group B Streptococcus), Escherichia coli, and Staphylococcus aureus are neonatal meningitis's most common causal agents. Despite efforts to vaccinate against the most common causes of bacterial neuro-infections, bacterial meningitis remains a significant cause of mortality and morbidity in Africa, with children below 5 years bearing the heaviest disease burden. The factors attributed to this continued high disease burden include poor infrastructure, continued war, instability, and difficulty in diagnosis of bacterial neuro-infections leading to delay in treatment and hence high morbidity. Despite having the highest disease burden, there is a paucity of African data on bacterial meningitis. In this article, we discuss the common etiologies of bacterial neuroinfectious diseases, diagnosis and the interplay between microorganisms and the immune system, and the value of neuroimmune changes in diagnostics and therapeutics.
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Affiliation(s)
- Tatiana Barichello
- Graduate Program in Health Sciences, University of Southern Santa Catarina (UNESC), Criciúma, SC, Brazil
- Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Carlos Henrique Rocha Catalão
- Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
- Department of Neuroscience and Behavioral Science, Ribeirao Preto Medical School, University of São Paulo (USP), Ribeirao Preto, SP, Brazil
| | - Ursula K. Rohlwink
- Pediatric Neurosurgery Unit, Red Cross War Memorial Children's Hospital, Cape Town, South Africa
- Division of Neurosurgery, University of Cape Town, Cape Town, South Africa
- Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Martijn van der Kuip
- Department of Pediatric Infectious Diseases and Immunology, Amsterdam Infection and Immunity Institute, Amsterdam University Medical Centers, Vrije Universiteit, Amsterdam, Netherlands
| | - Dan Zaharie
- Department of Anatomical Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- National Health Laboratory Services, Tygerberg Hospital, Cape Town, South Africa
| | - Regan S. Solomons
- Department of Pediatric and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Ronald van Toorn
- Department of Pediatric and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Marceline Tutu van Furth
- Department of Pediatric Infectious Diseases and Immunology, Amsterdam Infection and Immunity Institute, Amsterdam University Medical Centers, Vrije Universiteit, Amsterdam, Netherlands
| | - Rodrigo Hasbun
- Division of Infectious Diseases, Department of Internal Medicine, UT Health, McGovern Medical School, Houston, TX, United States
| | - Federico Iovino
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Vivian Ssonko Namale
- Columbia University Irving Medical Center and New York Presbyterian Hospital, New York, NY, United States
- Department of Paediatrics and Child Health, Makerere University College of Health Sciences, Kampala, Uganda
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5
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van de Beek D, Brouwer MC, Koedel U, Wall EC. Community-acquired bacterial meningitis. Lancet 2021; 398:1171-1183. [PMID: 34303412 DOI: 10.1016/s0140-6736(21)00883-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/25/2021] [Accepted: 04/07/2021] [Indexed: 12/19/2022]
Abstract
Progress has been made in the prevention and treatment of community-acquired bacterial meningitis during the past three decades but the burden of the disease remains high globally. Conjugate vaccines against the three most common causative pathogens (Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae) have reduced the incidence of disease, but with the replacement by non-vaccine pneumococcal serotypes and the emergence of bacterial strains with reduced susceptibility to antimicrobial treatment, meningitis continues to pose a major health challenge worldwide. In patients presenting with bacterial meningitis, typical clinical characteristics (such as the classic triad of neck stiffness, fever, and an altered mental status) might be absent and cerebrospinal fluid examination for biochemistry, microscopy, culture, and PCR to identify bacterial DNA are essential for the diagnosis. Multiplex PCR point-of-care panels in cerebrospinal fluid show promise in accelerating the diagnosis, but diagnostic accuracy studies to justify routine implementation are scarce and randomised, controlled studies are absent. Early administration of antimicrobial treatment (within 1 hour of presentation) improves outcomes and needs to be adjusted according to local emergence of drug resistance. Adjunctive dexamethasone treatment has proven efficacy beyond the neonatal age but only in patients from high-income countries. Further progress can be expected from implementing preventive measures, especially the development of new vaccines, implementation of hospital protocols aimed at early treatment, and new treatments targeting checkpoints of the inflammatory cascade.
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Affiliation(s)
- Diederik van de Beek
- Department of Neurology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Meibergdreef, Amsterdam, Netherlands.
| | - Matthijs C Brouwer
- Department of Neurology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Meibergdreef, Amsterdam, Netherlands
| | - Uwe Koedel
- Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
| | - Emma C Wall
- Research Department of Infection, University College London, London, UK; Francis Crick Institute, London, UK
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6
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Kamio N, Hayata M, Tamura M, Tanaka H, Imai K. Porphyromonas gingivalis enhances pneumococcal adhesion to human alveolar epithelial cells by increasing expression of host platelet-activating factor receptor. FEBS Lett 2021; 595:1604-1612. [PMID: 33792027 DOI: 10.1002/1873-3468.14084] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/18/2021] [Accepted: 03/18/2021] [Indexed: 12/30/2022]
Abstract
Streptococcus pneumoniae causes pneumonia by infecting the alveolar epithelium via binding to host receptors, such as the platelet-activating factor receptor (PAFR). Although chronic periodontitis has been identified as a pneumonia risk factor, how periodontopathic bacteria cause pneumonia is not known. We found that S. pneumoniae adhered to PAFR expressed on A549 human alveolar epithelial cells stimulated by Porphyromonas gingivalis culture supernatant, and this was abrogated by a PAFR-specific inhibitor. Among the major virulence factors of P. gingivalis [lipopolysaccharide (LPS), fimbriae and gingipains (Rgps and Kgp)], PAFR expression and pneumococcal adhesion were executed in an Rgp-dependent manner. LPS and fimbriae did not induce PAFR expression. Hence, our findings suggest that P. gingivalis enhances pneumococcal adhesion to human alveoli by inducing PAFR expression and that gingipains are responsible for this.
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Affiliation(s)
- Noriaki Kamio
- Department of Microbiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Mayumi Hayata
- Department of Microbiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Muneaki Tamura
- Department of Microbiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Hajime Tanaka
- Department of Microbiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Kenichi Imai
- Department of Microbiology, Nihon University School of Dentistry, Tokyo, Japan
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7
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Tuomanen EI. Perspective of a Pediatrician: Shared Pathogenesis of the Three Most Successful Pathogens of Children. Front Cell Infect Microbiol 2020; 10:585791. [PMID: 33178633 PMCID: PMC7593378 DOI: 10.3389/fcimb.2020.585791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/30/2020] [Indexed: 01/16/2023] Open
Abstract
Highly successful invasive pathogens exploit host vulnerabilities by adapting tools to co-opt highly conserved host features. This is especially true when pathogens develop ligands to hijack trafficking routes or signaling patterns of host receptors. In this context, highly successful pathogens can be grouped together by the patterns of organs infected and diseases they cause. In the case of this perspective, the focus is on the historically most successful invasive bacterial pathogens of children that cause pneumonia, sepsis and meningitis: Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. This triad shares a ligand to bind to PAF receptor to enter host cells despite early defenses by innate immunity. All three also target laminin receptor to cross endothelial barriers using a common set of molecular tools that may prove to be a design for a cross-protective vaccine.
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Affiliation(s)
- Elaine I Tuomanen
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, United States
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8
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García López E, Martín-Galiano AJ. The Versatility of Opportunistic Infections Caused by Gemella Isolates Is Supported by the Carriage of Virulence Factors From Multiple Origins. Front Microbiol 2020; 11:524. [PMID: 32296407 PMCID: PMC7136413 DOI: 10.3389/fmicb.2020.00524] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/11/2020] [Indexed: 12/29/2022] Open
Abstract
The molecular basis of the pathogenesis of the opportunistic invasive infections caused by isolates of the Gemella genus remains largely unknown. Moreover, inconsistencies in the current species assignation were detected after genome-level comparison of 16 public Gemella isolates. A literature search detected that, between the two most pathogenic species, Gemella morbillorum causes about twice the number of cases compared to Gemella haemolysans. These two species shared their mean diseases - sepsis and endocarditis - but differed in causing other syndromes. A number of well-known virulence factors were harbored by all species, such as a manganese transport/adhesin sharing 83% identity from oral endocarditis-causing streptococci. Likewise, all Gemellae carried the genes required for incorporating phosphorylcholine into their cell walls and encoded some choline-binding proteins. In contrast, other proteins were species-specific, which may justify the known epidemiological differences. G. haemolysans, but not G. morbillorum, harbor a gene cluster potentially encoding a polysaccharidic capsule. Species-specific surface determinants also included Rib and MucBP repeats, hemoglobin-binding NEAT domains, peptidases of C5a complement factor and domains that recognize extracellular matrix molecules exposed in damaged heart valves, such as collagen and fibronectin. Surface virulence determinants were associated with several taxonomically dispersed opportunistic genera of the oral microbiota, such as Granulicatella, Parvimonas, and Streptococcus, suggesting the existence of a horizontally transferrable gene reservoir in the oral environment, likely facilitated by close proximity in biofilms and ultimately linked to endocarditis. The identification of the Gemella virulence pool should be implemented in whole genome-based protocols to rationally predict the pathogenic potential in ongoing clinical infections caused by these poorly known bacterial pathogens.
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Affiliation(s)
- Ernesto García López
- Departamento de Biotecnología Microbiana y de Plantas, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Antonio J. Martín-Galiano
- Intrahospital Infections Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Majadahonda, Spain
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9
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Bhalla M, Hui Yeoh J, Lamneck C, Herring SE, Tchalla EYI, Heinzinger LR, Leong JM, Bou Ghanem EN. A1 adenosine receptor signaling reduces Streptococcus pneumoniae adherence to pulmonary epithelial cells by targeting expression of platelet-activating factor receptor. Cell Microbiol 2019; 22:e13141. [PMID: 31709673 DOI: 10.1111/cmi.13141] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/24/2019] [Accepted: 11/01/2019] [Indexed: 12/11/2022]
Abstract
Extracellular adenosine production is crucial for host resistance against Streptococcus pneumoniae (pneumococcus) and is thought to affect antibacterial immune responses by neutrophils. However, whether extracellular adenosine alters direct host-pathogen interaction remains unexplored. An important determinant for lung infection by S. pneumoniae is its ability to adhere to the pulmonary epithelium. Here we explored whether extracellular adenosine can directly impact bacterial adherence to lung epithelial cells. We found that signaling via A1 adenosine receptor significantly reduced the ability of pneumococci to bind human pulmonary epithelial cells. A1 receptor signaling blocked bacterial binding by reducing the expression of platelet-activating factor receptor, a host protein used by S. pneumoniae to adhere to host cells. In vivo, A1 was required for control of pneumococcal pneumonia as inhibiting it resulted in increased host susceptibility. As S. pneumoniae remain a leading cause of community-acquired pneumonia in the elderly, we explored the role of A1 in the age-driven susceptibility to infection. We found no difference in A1 pulmonary expression in young versus old mice. Strikingly, triggering A1 signaling boosted host resistance of old mice to S. pneumoniae pulmonary infection. This study demonstrates a novel mechanism by which extracellular adenosine modulates resistance to lung infection by targeting bacterial-host interactions.
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Affiliation(s)
- Manmeet Bhalla
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Jun Hui Yeoh
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Claire Lamneck
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Sydney E Herring
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Essi Y I Tchalla
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Lauren R Heinzinger
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - John M Leong
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Elsa N Bou Ghanem
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
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10
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Le Guennec L, Coureuil M, Nassif X, Bourdoulous S. Strategies used by bacterial pathogens to cross the blood-brain barrier. Cell Microbiol 2019; 22:e13132. [PMID: 31658405 DOI: 10.1111/cmi.13132] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 10/11/2019] [Accepted: 10/13/2019] [Indexed: 12/15/2022]
Abstract
The skull, spine, meninges, and cellular barriers at the blood-brain and the blood-cerebrospinal fluid interfaces well protect the brain and meningeal spaces against microbial invasion. However, once in the bloodstream, a range of pathogenic bacteria is able to reach the brain and cause meningitis. Despite advances in antibacterial therapy, bacterial meningitis remains one of the most important infectious diseases worldwide. The most common causative bacteria in children and adults are Streptococcus pneumoniae and Neisseria meningitidis associated with high morbidity and mortality, while among neonates, most cases of bacterial meningitis are due to group B Streptococcus and Escherichia coli. Here we summarise our current knowledge on the strategies used by these bacterial pathogens to survive in the bloodstream, to colonise the brain vasculature and to cross the blood-brain barrier.
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Affiliation(s)
- Loic Le Guennec
- Inserm (Institut National de la Sante et de la Recherche Medicale), U1016, Institut Cochin, Paris, France.,CNRS (Centre National de la recherche Scientifique), UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Mathieu Coureuil
- Inserm (Institut National de la Sante et de la Recherche Medicale), unité U1151, Institut-Necker-Enfants-Malades, Paris, France.,CNRS (Centre National de la recherche Scientifique), UMR 8253, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Faculté de médecine, Paris, France
| | - Xavier Nassif
- Inserm (Institut National de la Sante et de la Recherche Medicale), unité U1151, Institut-Necker-Enfants-Malades, Paris, France.,CNRS (Centre National de la recherche Scientifique), UMR 8253, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Faculté de médecine, Paris, France.,Assistance Publique - Hôpitaux de Paris, Hôpital Necker Enfants Malades, Paris, France
| | - Sandrine Bourdoulous
- Inserm (Institut National de la Sante et de la Recherche Medicale), U1016, Institut Cochin, Paris, France.,CNRS (Centre National de la recherche Scientifique), UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
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11
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Al-Obaidi MMJ, Desa MNM. Mechanisms of Blood Brain Barrier Disruption by Different Types of Bacteria, and Bacterial-Host Interactions Facilitate the Bacterial Pathogen Invading the Brain. Cell Mol Neurobiol 2018; 38:1349-1368. [PMID: 30117097 DOI: 10.1007/s10571-018-0609-2] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/06/2018] [Indexed: 12/19/2022]
Abstract
This review aims to elucidate the different mechanisms of blood brain barrier (BBB) disruption that may occur due to invasion by different types of bacteria, as well as to show the bacteria-host interactions that assist the bacterial pathogen in invading the brain. For example, platelet-activating factor receptor (PAFR) is responsible for brain invasion during the adhesion of pneumococci to brain endothelial cells, which might lead to brain invasion. Additionally, the major adhesin of the pneumococcal pilus-1, RrgA is able to bind the BBB endothelial receptors: polymeric immunoglobulin receptor (pIgR) and platelet endothelial cell adhesion molecule (PECAM-1), thus leading to invasion of the brain. Moreover, Streptococcus pneumoniae choline binding protein A (CbpA) targets the common carboxy-terminal domain of the laminin receptor (LR) establishing initial contact with brain endothelium that might result in BBB invasion. Furthermore, BBB disruption may occur by S. pneumoniae penetration through increasing in pro-inflammatory markers and endothelial permeability. In contrast, adhesion, invasion, and translocation through or between endothelial cells can be done by S. pneumoniae without any disruption to the vascular endothelium, upon BBB penetration. Internalins (InlA and InlB) of Listeria monocytogenes interact with its cellular receptors E-cadherin and mesenchymal-epithelial transition (MET) to facilitate invading the brain. L. monocytogenes species activate NF-κB in endothelial cells, encouraging the expression of P- and E-selectin, intercellular adhesion molecule 1 (ICAM-1), and Vascular cell adhesion protein 1 (VCAM-1), as well as IL-6 and IL-8 and monocyte chemoattractant protein-1 (MCP-1), all these markers assist in BBB disruption. Bacillus anthracis species interrupt both adherens junctions (AJs) and tight junctions (TJs), leading to BBB disruption. Brain microvascular endothelial cells (BMECs) permeability and BBB disruption are induced via interendothelial junction proteins reduction as well as up-regulation of IL-1α, IL-1β, IL-6, TNF-α, MCP-1, macrophage inflammatory proteins-1 alpha (MIP1α) markers in Staphylococcus aureus species. Streptococcus agalactiae or Group B Streptococcus toxins (GBS) enhance IL-8 and ICAM-1 as well as nitric oxide (NO) production from endothelial cells via the expression of inducible nitric oxide synthase (iNOS) enhancement, resulting in BBB disruption. While Gram-negative bacteria, Haemophilus influenza OmpP2 is able to target the common carboxy-terminal domain of LR to start initial interaction with brain endothelium, then invade the brain. H. influenza type b (HiB), can induce BBB permeability through TJ disruption. LR and PAFR binding sites have been recognized as common routes of CNS entrance by Neisseria meningitidis. N. meningitidis species also initiate binding to BMECs and induces AJs deformation, as well as inducing specific cleavage of the TJ component occludin through the release of host MMP-8. Escherichia coli bind to BMECs through LR, resulting in IL-6 and IL-8 release and iNOS production, as well as resulting in disassembly of TJs between endothelial cells, facilitating BBB disruption. Therefore, obtaining knowledge of BBB disruption by different types of bacterial species will provide a picture of how the bacteria enter the central nervous system (CNS) which might support the discovery of therapeutic strategies for each bacteria to control and manage infection.
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Affiliation(s)
- Mazen M Jamil Al-Obaidi
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
| | - Mohd Nasir Mohd Desa
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
- Halal Products Research Institute, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
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Biological substantiation of antipsychotic-associated pneumonia: Systematic literature review and computational analyses. PLoS One 2017; 12:e0187034. [PMID: 29077727 PMCID: PMC5659779 DOI: 10.1371/journal.pone.0187034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/12/2017] [Indexed: 02/07/2023] Open
Abstract
Introduction Antipsychotic (AP) safety has been widely investigated. However, mechanisms underlying AP-associated pneumonia are not well-defined. Aim The aim of this study was to investigate the known mechanisms of AP-associated pneumonia through a systematic literature review, confirm these mechanisms using an independent data source on drug targets and attempt to identify novel AP drug targets potentially linked to pneumonia. Methods A search was conducted in Medline and Web of Science to identify studies exploring the association between pneumonia and antipsychotic use, from which information on hypothesized mechanism of action was extracted. All studies had to be in English and had to concern AP use as an intervention in persons of any age and for any indication, provided that the outcome was pneumonia. Information on the study design, population, exposure, outcome, risk estimate and mechanism of action was tabulated. Public repositories of pharmacology and drug safety data were used to identify the receptor binding profile and AP safety events. Cytoscape was then used to map biological pathways that could link AP targets and off-targets to pneumonia. Results The literature search yielded 200 articles; 41 were included in the review. Thirty studies reported a hypothesized mechanism of action, most commonly activation/inhibition of cholinergic, histaminergic and dopaminergic receptors. In vitro pharmacology data confirmed receptor affinities identified in the literature review. Two targets, thromboxane A2 receptor (TBXA2R) and platelet activating factor receptor (PTAFR) were found to be novel AP target receptors potentially associated with pneumonia. Biological pathways constructed using Cytoscape identified plausible biological links potentially leading to pneumonia downstream of TBXA2R and PTAFR. Conclusion Innovative approaches for biological substantiation of drug-adverse event associations may strengthen evidence on drug safety profiles and help to tailor pharmacological therapies to patient risk factors.
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Abstract
As the largest receptor gene family in the human genome, with >800 members, the signal-transducing G protein-coupled receptors (GPCRs) play critical roles in nearly all conceivable physiological processes, ranging from the sensing of photons and odorants to metabolic homeostasis and migration of leukocytes. Unfortunately, an exhaustive review of the several hundred GPCRs expressed by myeloid cells/macrophages (P.J. Groot-Kormelink, L .Fawcett, P.D. Wright, M. Gosling, and T.C. Kent, BMC Immunol 12:57, 2012, doi:10.1186/1471-2172-13-57) is beyond the scope of this chapter; however, we will endeavor to cover the GPCRs that contribute to the major facets of macrophage biology, i.e., those whose expression is restricted to macrophages and the GPCRs involved in macrophage differentiation/polarization, microbial elimination, inflammation and resolution, and macrophage-mediated pathology. The chemokine receptors, a major group of myeloid GPCRs, will not be extensively covered as they are comprehensively reviewed elsewhere.
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Patel PS, Kearney JF. CD36 and Platelet-Activating Factor Receptor Promote House Dust Mite Allergy Development. THE JOURNAL OF IMMUNOLOGY 2017; 199:1184-1195. [PMID: 28667161 DOI: 10.4049/jimmunol.1700034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 06/07/2017] [Indexed: 12/21/2022]
Abstract
Over 89% of asthmatic children in underdeveloped countries demonstrate sensitivity to house dust mites (HDMs). The allergic response to HDMs is partially mediated by epithelial cell-derived cytokines that activate group 2 innate lymphoid cells, induce migration and activation of dendritic cells, and promote effector differentiation of HDM-specific TH2 cells. However, the contribution of innate receptor engagement on epithelial or dendritic cells by HDMs that ultimately mediates said innate and adaptive allergic responses is poorly understood. We and other investigators have demonstrated that HDMs express phosphorylcholine (PC) moieties. The major PC receptors involved in immune responses include CD36 and platelet-activating factor receptor (PAFR). Because CD36 and PAFR are expressed by epithelial cells and dendritic cells, and expression of these receptors is higher in human asthmatics, we determined whether engagement of CD36 or PAFR on epithelial or dendritic cells contributes to HDM allergy development. Testing bone marrow chimeric mice revealed that CD36 engagement on radioresistant cells and PAFR engagement on radioresistant and radiosensitive cells in the lung promote allergic responses to HDMs. Additionally, passive anti-PC IgM Abs administered intratracheally with HDMs decreased allergen uptake by epithelial cells and APCs in the lungs of C57BL/6 mice but not CD36-/- or PAFR-/- mice. These results show that CD36 and PAFR are important mediators of HDM allergy development and that inhibiting HDM engagement with PC receptors in the lung protects against allergic airway disease.
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Affiliation(s)
- Preeyam S Patel
- Department of Microbiology, The University of Alabama at Birmingham, Birmingham, AL 35294
| | - John F Kearney
- Department of Microbiology, The University of Alabama at Birmingham, Birmingham, AL 35294
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15
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Kc R, Shukla SD, Walters EH, O'Toole RF. Temporal upregulation of host surface receptors provides a window of opportunity for bacterial adhesion and disease. MICROBIOLOGY-SGM 2017; 163:421-430. [PMID: 28113047 DOI: 10.1099/mic.0.000434] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Host surface receptors provide bacteria with a foothold from which to attach, colonize and, in some cases, invade tissue and elicit human disease. In this review, we discuss several key host receptors and cognate adhesins that function in bacterial pathogenesis. In particular, we examine the elevated expression of host surface receptors such as CEACAM-1, CEACAM-6, ICAM-1 and PAFR in response to specific stimuli. We explore how upregulated receptors, in turn, expose the host to a range of bacterial infections in the respiratory tract. It is apparent that exploitation of receptor induction for bacterial adherence is not unique to one body system, but is also observed in the central nervous, gastrointestinal and urogenital systems. Prokaryotic pathogens which utilize this mechanism for their infectivity include Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis and Escherichia coli. A number of approaches have been used, in both in vitro and in vivo experimental models, to inhibit bacterial attachment to temporally expressed host receptors. Some of these novel strategies may advance future targeted interventions for the prevention and treatment of bacterial disease.
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Affiliation(s)
- Rajendra Kc
- School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS 7000, Australia
| | - Shakti D Shukla
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, The University of Newcastle, Newcastle, NSW 2308, Australia.,Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, New Lambton Heights, Newcastle, NSW 2305, Australia
| | - Eugene H Walters
- School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS 7000, Australia
| | - Ronan F O'Toole
- School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS 7000, Australia
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16
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Zheng GH, Xiong SQ, Chen HY, Mei LJ, Wang T. Association of platelet-activating factor receptor gene rs5938 (G/T) and rs313152 (T/C) polymorphisms with coronary heart disease and blood stasis syndrome in a Chinese Han population. Chin J Integr Med 2017; 23:893-900. [PMID: 28197937 DOI: 10.1007/s11655-017-2802-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To explore the association of the platelet-activating factor receptor (PAFR) gene rs5938, rs313152 and rs76744145 polymorphisms with coronary heart disease (CHD) and blood stasis syndrome (BSS) of CHD in Chinese Han population. METHODS A total of 570 CHD patients (299 with BSS and 271 with non-BSS) and 317 controls were enrolled. The PAFR gene rs5938, rs313152 and rs76744145 polymorphisms were genotyped using the multiplex SNaPshot technology. The statistical analysis was conducted using a multiple variable logistic regression model. RESULTS Significant differences were detected in the genotypes frequency distributions of the rs5938 (P<0.01), but not the rs313152 (P>0.05), between the controls and CHD patients. Individuals with an rs5938 or rs313152 mutated allele had a low risk for CHD [adjusted odds ratio (aOR)=0.35, 95% confidence interval (CI): 0.23 to 0.56, P<0.01; aOR=0.65, 95% CI: 0.46 to 0.91, P<0.05, respectively]. After the CHD patients were stratified as BSS or non-BSS according to their Chinese medicine patterns, the rs5938 polymorphism mutated alleles had a significant association with a low risk for BSS of CHD (aOR=0.32, 95% CI: 0.18 to 0.57, P<0.01) and non-BSS of CHD (aOR=0.31, 95% CI: 0.17 to 0.55, P<0.01). The rs313152 polymorphism was associated with a low risk for BSS (aOR=0.51, 95% CI: 0.33 to 0.79, P<0.01), but not for non-BSS (aOR=1.22, 95% CI: 0.81 to 1.85, P<0.05). Furthermore, the interaction effect of the rs5938 and rs313152 polymorphisms for BSS of CHD was significantly based on an aOR value associated with the combination of the rs5938 GT genotype with the rs313152 TC genotype of 0.27 (95% CI: 0.1 to 0.7, P<0.01). CONCLUSION The PAFR gene rs5938 or rs313152 polymorphisms might be a potential biomarker for susceptibility to CHD, especially to BSS of CHD in Chinese Han population.
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Affiliation(s)
- Guo-Hua Zheng
- College of Health Information Technology and Management, Shanghai University of Medicine and Health Sciences, Shanghai, 201318, China.
| | - Shang-Quan Xiong
- Department of Cardiologic Medicine, The Second People's Hospital of Fujian Province, Fuzhou, 350007, China
| | - Hai-Ying Chen
- The Second Clinic of Chinese Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Li-Juan Mei
- The Second Clinic of Chinese Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Ting Wang
- Department of Cardiologic Medicine, The Second People's Hospital of Fujian Province, Fuzhou, 350007, China
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17
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A journey into the brain: insight into how bacterial pathogens cross blood-brain barriers. Nat Rev Microbiol 2017; 15:149-159. [PMID: 28090076 DOI: 10.1038/nrmicro.2016.178] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The blood-brain barrier, which is one of the tightest barriers in the body, protects the brain from insults, such as infections. Indeed, only a few of the numerous blood-borne bacteria can cross the blood-brain barrier to cause meningitis. In this Review, we focus on invasive extracellular pathogens, such as Neisseria meningitidis, Streptococcus pneumoniae, group B Streptococcus and Escherichia coli, to review the obstacles that bacteria have to overcome in order to invade the meninges from the bloodstream, and the specific skills they have developed to bypass the blood-brain barrier. The medical importance of understanding how these barriers can be circumvented is underlined by the fact that we need to improve drug delivery into the brain.
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18
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Novick S, Shagan M, Blau K, Lifshitz S, Givon-Lavi N, Grossman N, Bodner L, Dagan R, Mizrachi Nebenzahl Y. Adhesion and invasion of Streptococcus pneumoniae to primary and secondary respiratory epithelial cells. Mol Med Rep 2016; 15:65-74. [PMID: 27922699 PMCID: PMC5355668 DOI: 10.3892/mmr.2016.5996] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/30/2016] [Indexed: 11/06/2022] Open
Abstract
The interaction between Streptococcus pneumoniae (S. pneumoniae) and the mucosal epithelial cells of its host is a prerequisite for pneumococcal disease development, yet the specificity of this interaction between different respiratory cells is not fully understood. In the present study, three areas were examined: i) The capability of the encapsulated S. pneumoniae serotype 3 strain (WU2) to adhere to and invade primary nasal‑derived epithelial cells in comparison to primary oral‑derived epithelial cells, A549 adenocarcinoma cells and BEAS‑2B viral transformed bronchial cells; ii) the capability of the unencapsulated 3.8DW strain (a WU2 derivative) to adhere to and invade the same cells over time; and iii) the ability of various genetically‑unrelated encapsulated and unencapsulated S. pneumoniae strains to adhere to and invade A549 lung epithelial cells. The results of the present study demonstrated that the encapsulated WU2 strain adhesion to and invasion of primary nasal epithelial cells was greatest, followed by BEAS‑2B, A549 and primary oral epithelial cells. By contrast, the unencapsulated 3.8‑DW strain invaded oral epithelial cells significantly more efficiently when compared to the nasal epithelial cells. In addition, unencapsulated S. pneumoniae strains adhered to and invaded the A459 cells significantly more efficiently than the encapsulated strains; this is consistent with previously published data. In conclusion, the findings presented in the current study indicated that the adhesion and invasion of the WU2 strain to primary nasal epithelial cells was more efficient compared with the other cultured respiratory epithelial cells tested, which corresponds to the natural course of S. pneumoniae infection and disease development. The target cell preference of unencapsulated strains was different from that of the encapsulated strains, which may be due to the exposure of cell wall proteins.
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Affiliation(s)
- Sara Novick
- Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
| | - Marilous Shagan
- Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
| | - Karin Blau
- Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
| | - Sarit Lifshitz
- Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
| | - Noga Givon-Lavi
- Pediatric Infectious Disease Unit, Soroka University Medical Center, Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
| | - Nili Grossman
- Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
| | - Lipa Bodner
- Oral and Maxillofacial Surgery Unit, Soroka University Medical Center, Beer Sheva 84105, Israel
| | - Ron Dagan
- Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
| | - Yaffa Mizrachi Nebenzahl
- Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben‑Gurion University of The Negev, Beer Sheva 84101, Israel
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van de Beek D, Brouwer M, Hasbun R, Koedel U, Whitney CG, Wijdicks E. Community-acquired bacterial meningitis. Nat Rev Dis Primers 2016; 2:16074. [PMID: 27808261 DOI: 10.1038/nrdp.2016.74] [Citation(s) in RCA: 167] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Meningitis is an inflammation of the meninges and subarachnoid space that can also involve the brain cortex and parenchyma. It can be acquired spontaneously in the community - community-acquired bacterial meningitis - or in the hospital as a complication of invasive procedures or head trauma (nosocomial bacterial meningitis). Despite advances in treatment and vaccinations, community-acquired bacterial meningitis remains one of the most important infectious diseases worldwide. Streptococcus pneumoniae and Neisseria meningitidis are the most common causative bacteria and are associated with high mortality and morbidity; vaccines targeting these organisms, which have designs similar to the successful vaccine that targets Haemophilus influenzae type b meningitis, are now being used in many routine vaccination programmes. Experimental and genetic association studies have increased our knowledge about the pathogenesis of bacterial meningitis. Early antibiotic treatment improves the outcome, but the growing emergence of drug resistance as well as shifts in the distribution of serotypes and groups are fuelling further development of new vaccines and treatment strategies. Corticosteroids were found to be beneficial in high-income countries depending on the bacterial species. Further improvements in the outcome are likely to come from dampening the host inflammatory response and implementing preventive measures, especially the development of new vaccines.
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Affiliation(s)
- Diederik van de Beek
- Department of Neurology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, P.O. BOX 22660, 1100DD Amsterdam, The Netherlands
| | - Matthijs Brouwer
- Department of Neurology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, P.O. BOX 22660, 1100DD Amsterdam, The Netherlands
| | - Rodrigo Hasbun
- Department of Internal Medicine, UT Health McGovern Medical School, Houston, Texas, USA
| | - Uwe Koedel
- Department of Neurology, Clinic Grosshadern of the Ludwig-Maximilians University of Munich, Munich, Germany
| | - Cynthia G Whitney
- Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Eelco Wijdicks
- Division of Critical Care Neurology, Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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20
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Zhang Y, Wang X, Wang S, Zhang Q, Peng S, Li X, Zhang Y, Qiao Y. In silico investigation of the association of the TRPM8 ion channel with the pungent flavor of Chinese herbs. JOURNAL OF TRADITIONAL CHINESE MEDICAL SCIENCES 2016. [DOI: 10.1016/j.jtcms.2016.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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21
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How Does Streptococcus pneumoniae Invade the Brain? Trends Microbiol 2016; 24:307-315. [DOI: 10.1016/j.tim.2015.12.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/18/2015] [Accepted: 12/28/2015] [Indexed: 02/07/2023]
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22
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Suri R, Periselneris J, Lanone S, Zeidler-Erdely PC, Melton G, Palmer KT, Andujar P, Antonini JM, Cohignac V, Erdely A, Jose RJ, Mudway I, Brown J, Grigg J. Exposure to welding fumes and lower airway infection with Streptococcus pneumoniae. J Allergy Clin Immunol 2016; 137:527-534.e7. [PMID: 26277596 PMCID: PMC4747856 DOI: 10.1016/j.jaci.2015.06.033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/29/2015] [Accepted: 06/29/2015] [Indexed: 12/18/2022]
Abstract
BACKGROUND Welders are at increased risk of pneumococcal pneumonia. The mechanism for this association is not known. The capacity of pneumococci to adhere to and infect lower airway cells is mediated by host-expressed platelet-activating factor receptor (PAFR). OBJECTIVE We sought to assess the effect of mild steel welding fumes (MS-WF) on PAFR-dependent pneumococcal adhesion and infection to human airway cells in vitro and on pneumococcal airway infection in a mouse model. METHODS The oxidative potential of MS-WF was assessed by their capacity to reduce antioxidants in vitro. Pneumococcal adhesion and infection of A549, BEAS-2B, and primary human bronchial airway cells were assessed by means of quantitative bacterial culture and expressed as colony-forming units (CFU). After intranasal instillation of MS-WF, mice were infected with Streptococcus pneumoniae, and bronchoalveolar lavage fluid (BALF) and lung CFU values were determined. PAFR protein levels were assessed by using immunofluorescence and immunohistochemistry, and PAFR mRNA expression was assessed by using quantitative PCR. PAFR was blocked by CV-3988, and oxidative stress was attenuated by N-acetylcysteine. RESULTS MS-WF exhibited high oxidative potential. In A549 and BEAS-2B cells MS-WF increased pneumococcal adhesion and infection and PAFR protein expression. Both CV-3988 and N-acetylcysteine reduced MS-WF-stimulated pneumococcal adhesion and infection of airway cells. MS-WF increased mouse lung PAFR mRNA expression and increased BALF and lung pneumococcal CFU values. In MS-WF-exposed mice CV-3988 reduced BALF CFU values. CONCLUSIONS Hypersusceptibility of welders to pneumococcal pneumonia is in part mediated by the capacity of welding fumes to increase PAFR-dependent pneumococcal adhesion and infection of lower airway cells.
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Affiliation(s)
- Reetika Suri
- Blizard Institute, Queen Mary University of London, London, United Kingdom
| | - Jimstan Periselneris
- Centre for Inflammation and Tissue Repair, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Sophie Lanone
- Inserm U955 Équipe 4, Faculté de Médecine, Créteil, France
| | - Patti C Zeidler-Erdely
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV
| | | | - Keith T Palmer
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, United Kingdom
| | - Pascal Andujar
- Inserm U955 Équipe 4, Faculté de Médecine, Créteil, France
| | - James M Antonini
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV
| | | | - Aaron Erdely
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV
| | - Ricardo J Jose
- Centre for Inflammation and Tissue Repair, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Ian Mudway
- MRC-PHE Centre for Environment and Health, Analytical & Environmental Sciences Division, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
| | - Jeremy Brown
- Centre for Inflammation and Tissue Repair, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Jonathan Grigg
- Blizard Institute, Queen Mary University of London, London, United Kingdom.
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23
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Reprint of: “Synthetic lipids and their role in defining macromolecular assemblies”. Chem Phys Lipids 2016; 194:149-57. [DOI: 10.1016/j.chemphyslip.2015.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/29/2015] [Accepted: 07/31/2015] [Indexed: 11/23/2022]
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24
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Shukla SD, Muller HK, Latham R, Sohal SS, Walters EH. Platelet-activating factor receptor (PAFr) is upregulated in small airways and alveoli of smokers and COPD patients. Respirology 2015; 21:504-10. [PMID: 26662379 DOI: 10.1111/resp.12709] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 10/01/2015] [Accepted: 10/01/2015] [Indexed: 01/12/2023]
Abstract
BACKGROUND AND OBJECTIVE PAFr is a cell adhesion site for specific bacteria, notably non-typeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae. We previously published that PAFr expression is significantly upregulated in the large airways of smokers, especially in COPD. We have now investigated PAFr expression in the epithelium and Rbm of small airways and in the alveolar compartment in smokers and patients with both COPD and small airway disease. METHODS We evaluated PAFr expression cross-sectionally in resected lung tissue from: eight smokers with normal lung function (NLFS); 10 with smoking-related small airway narrowing only; eight COPD smokers; 10 COPD ex-smokers, and compared these with nine control tissues. Anti-PAFr immunostaining was quantified using computer-aided image analysis. RESULTS Significantly increased PAFr expression in small airway epithelium of all clinical groups was found compared with controls (P < 0.01). Moreover, epithelial PAFr expression was upregulated in COPD smokers compared with NLFS (P < 0.05), but not when compared with COPD ex-smokers or patients with only small airways disease. Smoking history (pack-year) correlated significantly with PAFr expression in the currently smoking individuals, especially in NLFS (r = 0.9; P < 0.002). An increase above normal in PAFr-expressing cells in the airway epithelial Rbm was only significant in COPD smokers (P < 0.007). An upregulation of PAFr-expressing cell in alveolar epithelium was uniformly found in all clinical groups compared with normal control (P < 0.01). CONCLUSION Epithelial PAFr expression is upregulated in small airways and alveoli in smokers and COPD. Increased expression of PAFr could be crucial in facilitating acute and chronic respiratory infection with specific respiratory pathogens.
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Affiliation(s)
- Shakti Dhar Shukla
- NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Hans Konrad Muller
- NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Roger Latham
- NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Sukhwinder Singh Sohal
- NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia.,School of Health Sciences, University of Tasmania, Launceston, Tasmania, Australia
| | - Eugene Haydn Walters
- NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
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Walters KA, D'Agnillo F, Sheng ZM, Kindrachuk J, Schwartzman LM, Kuestner RE, Chertow DS, Golding BT, Taubenberger JK, Kash JC. 1918 pandemic influenza virus and Streptococcus pneumoniae co-infection results in activation of coagulation and widespread pulmonary thrombosis in mice and humans. J Pathol 2015; 238:85-97. [PMID: 26383585 DOI: 10.1002/path.4638] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 08/25/2015] [Accepted: 09/07/2015] [Indexed: 12/15/2022]
Abstract
To study bacterial co-infection following 1918 H1N1 influenza virus infection, mice were inoculated with the 1918 influenza virus, followed by Streptococcus pneumoniae (SP) 72 h later. Co-infected mice exhibited markedly more severe disease, shortened survival time and more severe lung pathology, including widespread thrombi. Transcriptional profiling revealed activation of coagulation only in co-infected mice, consistent with the extensive thrombogenesis observed. Immunohistochemistry showed extensive expression of tissue factor (F3) and prominent deposition of neutrophil elastase on endothelial and epithelial cells in co-infected mice. Lung sections of SP-positive 1918 autopsy cases showed extensive thrombi and prominent staining for F3 in alveolar macrophages, monocytes, neutrophils, endothelial and epithelial cells, in contrast to co-infection-positive 2009 pandemic H1N1 autopsy cases. This study reveals that a distinctive feature of 1918 influenza virus and SP co-infection in mice and humans is extensive expression of tissue factor and activation of the extrinsic coagulation pathway leading to widespread pulmonary thrombosis.
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Affiliation(s)
| | - Felice D'Agnillo
- Laboratory of Biochemistry and Vascular Biology, Division of Hematology Research and Review, Center for Biologics Evaluation and Research, Office of Blood Research and Review, Food and Drug Administration, Silver Spring, MD, USA
| | - Zong-Mei Sheng
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, MD, 20892, USA
| | - Jason Kindrachuk
- Critical Care Medicine Department, National Institutes of Health (NIH), Bethesda, MD, USA
| | - Louis M Schwartzman
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, MD, 20892, USA
| | | | - Daniel S Chertow
- Critical Care Medicine Department, National Institutes of Health (NIH), Bethesda, MD, USA.,Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, MD, 20892, USA
| | - Basil T Golding
- Laboratory of Biochemistry and Vascular Biology, Division of Hematology Research and Review, Center for Biologics Evaluation and Research, Office of Blood Research and Review, Food and Drug Administration, Silver Spring, MD, USA
| | - Jeffery K Taubenberger
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, MD, 20892, USA
| | - John C Kash
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, MD, 20892, USA
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26
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Parrill AL. Synthetic lipids and their role in defining macromolecular assemblies. Chem Phys Lipids 2015; 191:38-47. [DOI: 10.1016/j.chemphyslip.2015.07.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/29/2015] [Accepted: 07/31/2015] [Indexed: 10/23/2022]
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Impact of the glpQ2 gene on virulence in a Streptococcus pneumoniae serotype 19A sequence type 320 strain. Infect Immun 2014; 83:682-92. [PMID: 25422269 DOI: 10.1128/iai.02357-14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Glycerophosphodiester phosphodiesterase (GlpQ) metabolizes glycerophosphorylcholine from the lung epithelium to produce free choline, which is transformed into phosphorylcholine and presented on the surfaces of many respiratory pathogens. Two orthologs of glpQ genes are found in Streptococcus pneumoniae: glpQ, with a membrane motif, is widespread in pneumococci, whereas glpQ2, which shares high similarity with glpQ in Haemophilus influenzae and Mycoplasma pneumoniae, is present only in S. pneumoniae serotype 3, 6B, 19A, and 19F strains. Recently, serotype 19A has emerged as an epidemiological etiology associated with invasive pneumococcal diseases. Thus, we investigated the pathophysiological role of glpQ2 in a serotype 19A sequence type 320 (19AST320) strain, which was the prevalent sequence type in 19A associated with severe pneumonia and invasive pneumococcal disease in pediatric patients. Mutations in glpQ2 reduced phosphorylcholine expression and the anchorage of choline-binding proteins to the pneumococcal surface during the exponential phase, where the mutants exhibited reduced autolysis and lower natural transformation abilities than the parent strain. The deletion of glpQ2 also decreased the adherence and cytotoxicity to human lung epithelial cell lines, whereas these functions were indistinguishable from those of the wild type in complementation strains. In a murine respiratory tract infection model, glpQ2 was important for nasopharynx and lung colonization. Furthermore, infection with a glpQ2 mutant decreased the severity of pneumonia compared with the parent strain, and glpQ2 gene complementation restored the inflammation level. Therefore, glpQ2 enhances surface phosphorylcholine expression in S. pneumoniae 19AST320 during the exponential phase, which contributes to the severity of pneumonia by promoting adherence and host cell cytotoxicity.
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Platelet endothelial cell adhesion molecule-1, a putative receptor for the adhesion of Streptococcus pneumoniae to the vascular endothelium of the blood-brain barrier. Infect Immun 2014; 82:3555-66. [PMID: 24914219 DOI: 10.1128/iai.00046-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Gram-positive bacterium Streptococcus pneumoniae is the main causative agent of bacterial meningitis. S. pneumoniae is thought to invade the central nervous system via the bloodstream by crossing the vascular endothelium of the blood-brain barrier. The exact mechanism by which pneumococci cross endothelial cell barriers before meningitis develops is unknown. Here, we investigated the role of PECAM-1/CD31, one of the major endothelial cell adhesion molecules, in S. pneumoniae adhesion to vascular endothelium of the blood-brain barrier. Mice were intravenously infected with pneumococci and sacrificed at various time points to represent stages preceding meningitis. Immunofluorescent analysis of brain tissue of infected mice showed that pneumococci colocalized with PECAM-1. In human brain microvascular endothelial cells (HBMEC) incubated with S. pneumoniae, we observed a clear colocalization between PECAM-1 and pneumococci. Blocking of PECAM-1 reduced the adhesion of S. pneumoniae to endothelial cells in vitro, implying that PECAM-1 is involved in pneumococcal adhesion to the cells. Furthermore, using endothelial cell protein lysates, we demonstrated that S. pneumoniae physically binds to PECAM-1. Moreover, both in vitro and in vivo PECAM-1 colocalizes with the S. pneumoniae adhesion receptor pIgR. Lastly, immunoprecipitation experiments revealed that PECAM-1 can physically interact with pIgR. In summary, we show for the first time that blood-borne S. pneumoniae colocalizes with PECAM-1 expressed by brain microvascular endothelium and that, in addition, they colocalize with pIgR. We hypothesize that this interaction plays a role in pneumococcal binding to the blood-brain barrier vasculature prior to invasion into the brain.
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Dong YH, Chang CH, Wu FLL, Shen LJ, Calverley PM, Löfdahl CG, Lai MS, Mahler DA. Use of Inhaled Corticosteroids in Patients With COPD and the Risk of TB and Influenza. Chest 2014; 145:1286-1297. [DOI: 10.1378/chest.13-2137] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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30
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Iovino F, Molema G, Bijlsma JJE. Streptococcus pneumoniae Interacts with pIgR expressed by the brain microvascular endothelium but does not co-localize with PAF receptor. PLoS One 2014; 9:e97914. [PMID: 24841255 PMCID: PMC4026408 DOI: 10.1371/journal.pone.0097914] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 04/26/2014] [Indexed: 01/19/2023] Open
Abstract
Streptococcus pneumoniae is thought to adhere to the blood-brain barrier (BBB) endothelium prior to causing meningitis. The platelet activating factor receptor (PAFR) has been implicated in this adhesion but there is a paucity of data demonstrating direct binding of the bacteria to PAFR. Additionally, studies that inhibit PAFR strongly suggest that alternative receptors for pneumococci are present on the endothelium. Therefore, we studied the roles of PAFR and pIgR, an established epithelial pneumococcal receptor, in pneumococcal adhesion to brain endothelial cells in vivo. Mice were intravenously infected with pneumococci and sacrificed at various time points before meningitis onset. Co-localization of bacteria with PAFR and pIgR was investigated using immunofluorescent analysis of the brain tissue. In vitro blocking with antibodies and incubation of pneumococci with endothelial cell lysates were used to further probe bacteria-receptor interaction. In vivo as well as in vitro pneumococci did not co-localize with PAFR. On the other hand the majority of S. pneumoniae co-localized with endothelial pIgR and pIgR blocking reduced pneumococcal adhesion to endothelial cells. Pneumococci physically interacted with pIgR in endothelial cell lysates. In conclusion, bacteria did not associate with PAFR, indicating an indirect role of PAFR in pneumococcal adhesion to endothelial cells. In contrast, pIgR on the BBB endothelium may represent a novel pneumococcal adhesion receptor.
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Affiliation(s)
- Federico Iovino
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Grietje Molema
- Department of Pathology & Medical Biology, Medical Biology section, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jetta J. E. Bijlsma
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- * E-mail:
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Abstract
G-protein–coupled receptors (GPCRs) still offer enormous scope for new therapeutic targets. Currently marketed agents are dominated by those with activity at aminergic receptors and yet they account for only ~10% of the family. Progress up until now with other subfamilies, notably orphans, Family A/peptide, Family A/lipid, Family B, Family C, and Family F, has been, at best, patchy. This may be attributable to the heterogeneous nature of GPCRs, their endogenous ligands, and consequently their binding sites. Our appreciation of receptor similarity has arguably been too simplistic, and screening collections have not necessarily been well suited to identifying leads in new areas. Despite the relative shortage of high-quality tool molecules in a number of cases, there is an emerging, and increasingly substantial, body of evidence associating many as yet “undrugged” receptors with a very wide range of diseases. Significant advances in our understanding of receptor pharmacology and technical advances in screening, protein X-ray crystallography, and ligand design methods are paving the way for new successes in the area. Exploitation of allosteric mechanisms; alternative signaling pathways such as G12/13, Gβγ, and β-arrestin; the discovery of “biased” ligands; and the emergence of GPCR-protein complexes as potential drug targets offer scope for new and much improved drugs.
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