1
|
Thorsdottir S, Henriques-Normark B, Iovino F. The Role of Microglia in Bacterial Meningitis: Inflammatory Response, Experimental Models and New Neuroprotective Therapeutic Strategies. Front Microbiol 2019; 10:576. [PMID: 30967852 PMCID: PMC6442515 DOI: 10.3389/fmicb.2019.00576] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/06/2019] [Indexed: 12/11/2022] Open
Abstract
Microglia have a pivotal role in the pathophysiology of bacterial meningitis. The goal of this review is to provide an overview on how microglia respond to bacterial pathogens targeting the brain, how the interplay between microglia and bacteria can be studied experimentally, and possible ways to use gained knowledge to identify novel preventive and therapeutic strategies. We discuss the dual role of microglia in disease development, the beneficial functions crucial for bacterial clearing, and the destructive properties through triggering neuroinflammation, characterized by cytokine and chemokine release which leads to leukocyte trafficking through the brain vascular endothelium and breakdown of the blood-brain barrier integrity. Due to intrinsic complexity of microglia and up until recently lack of specific markers, the study of microglial response to bacterial pathogens is challenging. New experimental models and techniques open up possibilities to accelerate progress in the field. We review existing models and discuss possibilities and limitations. Finally, we summarize recent findings where bacterial virulence factors are identified to be important for the microglial response, and how manipulation of evoked responses could be used for therapeutic or preventive purposes. Among promising approaches are: modulations of microglia phenotype switching toward anti-inflammatory and phagocytic functions, the use of non-bacterolytic antimicrobials, preventing release of bacterial components into the neural milieu and consequential amplification of immune activation, and protection of the blood-brain barrier integrity.
Collapse
Affiliation(s)
- Sigrun Thorsdottir
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Bioclinicum, Stockholm, Sweden.,Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Bioclinicum, Stockholm, Sweden.,Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.,Singapore Centre for Environmental Life Sciences Engineering (SCELSE) and Lee Kong Chian School of Medicine (LKC), Nanyang Technological University (NTU), Singapore, Singapore
| | - Federico Iovino
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Bioclinicum, Stockholm, Sweden.,Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden
| |
Collapse
|
2
|
Blood‒Brain Barrier Pathology and CNS Outcomes in Streptococcus pneumoniae Meningitis. Int J Mol Sci 2018; 19:ijms19113555. [PMID: 30423890 PMCID: PMC6275034 DOI: 10.3390/ijms19113555] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/05/2018] [Accepted: 11/09/2018] [Indexed: 12/20/2022] Open
Abstract
Streptococcus pneumoniae is a major meningitis-causing pathogen globally, bringing about significant morbidity and mortality, as well as long-term neurological sequelae in almost half of the survivors. Subsequent to nasopharyngeal colonisation and systemic invasion, translocation across the blood‒brain barrier (BBB) by S. pneumoniae is a crucial early step in the pathogenesis of meningitis. The BBB, which normally protects the central nervous system (CNS) from deleterious molecules within the circulation, becomes dysfunctional in S. pneumoniae invasion due to the effects of pneumococcal toxins and a heightened host inflammatory environment of cytokines, chemokines and reactive oxygen species intracranially. The bacteria‒host interplay within the CNS likely determines not only the degree of BBB pathological changes, but also host survival and the extent of neurological damage. This review explores the relationship between S. pneumoniae bacteria and the host inflammatory response, with an emphasis on the BBB and its roles in CNS protection, as well as both the acute and long-term pathogenesis of meningitis.
Collapse
|
3
|
Cavalieri D, Di Paola M, Rizzetto L, Tocci N, De Filippo C, Lionetti P, Ardizzoni A, Colombari B, Paulone S, Gut IG, Berná L, Gut M, Blanc J, Kapushesky M, Pericolini E, Blasi E, Peppoloni S. Genomic and Phenotypic Variation in Morphogenetic Networks of Two Candida albicans Isolates Subtends Their Different Pathogenic Potential. Front Immunol 2018; 8:1997. [PMID: 29403478 PMCID: PMC5780349 DOI: 10.3389/fimmu.2017.01997] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 12/22/2017] [Indexed: 01/29/2023] Open
Abstract
The transition from commensalism to pathogenicity of Candida albicans reflects both the host inability to mount specific immune responses and the microorganism’s dimorphic switch efficiency. In this study, we used whole genome sequencing and microarray analysis to investigate the genomic determinants of the phenotypic changes observed in two C. albicans clinical isolates (YL1 and YQ2). In vitro experiments employing epithelial, microglial, and peripheral blood mononuclear cells were thus used to evaluate C. albicans isolates interaction with first line host defenses, measuring adhesion, susceptibility to phagocytosis, and induction of secretory responses. Moreover, a murine model of peritoneal infection was used to compare the in vivo pathogenic potential of the two isolates. Genome sequence and gene expression analysis of C. albicans YL1 and YQ2 showed significant changes in cellular pathways involved in environmental stress response, adhesion, filamentous growth, invasiveness, and dimorphic transition. This was in accordance with the observed marked phenotypic differences in biofilm production, dimorphic switch efficiency, cell adhesion, invasion, and survival to phagocyte-mediated host defenses. The mutations in key regulators of the hyphal growth pathway in the more virulent strain corresponded to an overall greater number of budding yeast cells released. Compared to YQ2, YL1 consistently showed enhanced pathogenic potential, since in vitro, it was less susceptible to ingestion by phagocytic cells and more efficient in invading epithelial cells, while in vivo YL1 was more effective than YQ2 in recruiting inflammatory cells, eliciting IL-1β response and eluding phagocytic cells. Overall, these results indicate an unexpected isolate-specific variation in pathways important for host invasion and colonization, showing how the genetic background of C. albicans may greatly affect its behavior both in vitro and in vivo. Based on this approach, we propose that the co-occurrence of changes in sequence and expression in genes and pathways driving dimorphic transition and pathogenicity reflects a selective balance between traits favoring dissemination of the pathogen and traits involved in host defense evasion. This study highlights the importance of investigating strain-level, rather than species level, differences, when determining fungal–host interactions and defining commensal or pathogen behavior.
Collapse
Affiliation(s)
- Duccio Cavalieri
- Dipartimento di Biologia, Università di Firenze, Florence, Italy
| | - Monica Di Paola
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Università di Firenze, Florence, Italy
| | - Lisa Rizzetto
- Centro Ricerca e Innovazione, Fondazione Edmund Mach, San Michele all'Adige, Italy
| | - Noemi Tocci
- Centro Ricerca e Innovazione, Fondazione Edmund Mach, San Michele all'Adige, Italy
| | - Carlotta De Filippo
- Institute of Agricultural Biology and Biotechnology, National Research Council (CNR), Pisa, Italy
| | - Paolo Lionetti
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Università di Firenze, Florence, Italy
| | - Andrea Ardizzoni
- Dipartimento di Medicina Diagnostica, Clinica e di Sanità Pubblica, Università di Modena e Reggio Emilia, Modena, Italy
| | - Bruna Colombari
- Dipartimento di Medicina Diagnostica, Clinica e di Sanità Pubblica, Università di Modena e Reggio Emilia, Modena, Italy
| | - Simona Paulone
- Dipartimento di Medicina Diagnostica, Clinica e di Sanità Pubblica, Università di Modena e Reggio Emilia, Modena, Italy
| | - Ivo G Gut
- Centro Nacional de Anàlisi Genòmica, Barcelona, Spain
| | - Luisa Berná
- Unidad de Biologia Molecular, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Marta Gut
- Centro Nacional de Anàlisi Genòmica, Barcelona, Spain
| | - Julie Blanc
- Centro Nacional de Anàlisi Genòmica, Barcelona, Spain
| | - Misha Kapushesky
- European Bioinformatics Institute (EMBL-EBI), Cambridge, United Kingdom
| | - Eva Pericolini
- Dipartimento di Medicina Diagnostica, Clinica e di Sanità Pubblica, Università di Modena e Reggio Emilia, Modena, Italy
| | - Elisabetta Blasi
- Dipartimento di Medicina Diagnostica, Clinica e di Sanità Pubblica, Università di Modena e Reggio Emilia, Modena, Italy
| | - Samuele Peppoloni
- Dipartimento di Medicina Diagnostica, Clinica e di Sanità Pubblica, Università di Modena e Reggio Emilia, Modena, Italy
| |
Collapse
|
4
|
Ricci S, Gerlini A, Pammolli A, Chiavolini D, Braione V, Tripodi SA, Colombari B, Blasi E, Oggioni MR, Peppoloni S, Pozzi G. Contribution of different pneumococcal virulence factors to experimental meningitis in mice. BMC Infect Dis 2013; 13:444. [PMID: 24059458 PMCID: PMC3848944 DOI: 10.1186/1471-2334-13-444] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 09/13/2013] [Indexed: 11/28/2022] Open
Abstract
Background Pneumococcal meningitis (PM) is a life-threatening disease with a high case-fatality rate and elevated risk for serious neurological sequelae. In this study, we investigated the contribution of three major virulence factors of Streptococcus pneumoniae, the capsule, pneumococcal surface protein A (PspA) and C (PspC), to the pathogenesis of experimental PM. Methods Mice were challenged by the intracranial route with the serotype 4 TIGR4 strain (wt) and three isogenic mutants devoid of PspA, PspC, and the capsule. Survival, bacterial counts, and brain histology were carried out. To study the interaction between S. pneumoniae mutants and microglia, phagocytosis and survival experiments were performed using the BV2 mouse microglial cell line. Results Virulence of the PspC mutant was comparable to that of TIGR4. In contrast, survival of animals challenged with the PspA mutant was significantly increased compared with the wt, and the mutant was also impaired at replicating in the brain and blood of infected mice. Brain histology indicated that all strains, except for the unencapsulated mutant, caused PM. Analysis of inflammation and damage in the brain of mice infected with TIGR4 or its unencapsulated mutant demonstrated that the rough strain was unable to induce inflammation and neuronal injury, even at high challenge doses. Results with BV2 cells showed no differences in phagocytic uptake between wt and mutants. In survival assays, however, the PspA mutant showed significantly reduced survival in microglia compared with the wt. Conclusions PspA contributed to PM pathogenesis possibly by interacting with microglia at early infection stages, while PspC had limited importance in the disease. The rough mutant did not cause brain inflammation, neuronal damage or mouse death, strengthening the key role of the capsule in PM.
Collapse
Affiliation(s)
- Susanna Ricci
- Department of Medical Biotechnologies, Laboratory of Molecular Microbiology and Biotechnology (LA,M,M,B,), University of Siena and Siena University Hospital, Siena 53100, Italy.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|