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Xu Y, Wang J, Qin X, Liu J. Advances in the pathogenesis and treatment of pneumococcal meningitis. Virulence 2024; 15:2387180. [PMID: 39192572 PMCID: PMC11364070 DOI: 10.1080/21505594.2024.2387180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 07/04/2024] [Accepted: 07/28/2024] [Indexed: 08/29/2024] Open
Abstract
Streptococcus pneumoniae is a common pathogen associated with community-acquired bacterial meningitis, characterized by high morbidity and mortality rates. While vaccination reduces the incidence of meningitis, many survivors experience severe brain damage and corresponding sequelae. The pathogenesis of pneumococcal meningitis has not been fully elucidated. Currently, meningitis requires bacterial disruption of the blood - brain barrier, a process that involves the interaction of bacterial surface components with host cells and various inflammatory responses. This review delineates the global prevalence, pathogenesis, and treatment strategies of pneumococcal meningitis. The objective is to enhance the thorough comprehension of the clinical manifestations and biological mechanisms of the disease, thereby enabling more efficient prevention, diagnosis, and therapeutic interventions.
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Affiliation(s)
- Yiyun Xu
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Liaoning Clinical Research Center for Laboratory Medicine, Shenyang, China
| | - Ji Wang
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Liaoning Clinical Research Center for Laboratory Medicine, Shenyang, China
| | - Xiaosong Qin
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Liaoning Clinical Research Center for Laboratory Medicine, Shenyang, China
| | - Jianhua Liu
- Department of Laboratory Medicine, Shengjing Hospital of China Medical University, Liaoning Clinical Research Center for Laboratory Medicine, Shenyang, China
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2
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Ahmad D, Linares I, Pietropaoli A, Waugh RE, McGrath JL. Sided Stimulation of Endothelial Cells Modulates Neutrophil Trafficking in an In Vitro Sepsis Model. Adv Healthc Mater 2024; 13:e2304338. [PMID: 38547536 PMCID: PMC11338706 DOI: 10.1002/adhm.202304338] [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: 12/06/2023] [Revised: 03/22/2024] [Indexed: 04/09/2024]
Abstract
While the role of dysregulated polymorphonuclear leukocyte (PMN) transmigration in septic mediated tissue damage is well documented, strategies to mitigate aberrant transmigration across endothelium have yet to yield viable therapeutics. Recently, microphysiological systems (MPS) have emerged as novel in vitro mimetics that facilitate the development of human models of disease. With this advancement, aspects of endothelial physiology that are difficult to assess with other models can be directly probed. In this study, the role of endothelial cell (EC) apicobasal polarity on leukocyte trafficking response is evaluated with the µSiM-MVM (microphysiological system enabled by a silicon membrane - microvascular mimetic). Here, ECs are stimulated either apically or basally with a cytokine cocktail to model a septic-like challenge before introducing healthy donor PMNs into the device. Basally oriented stimulation generated a stronger PMN transmigratory response versus apical stimulation. Importantly, healthy PMNs are unable to migrate towards a bacterial peptide chemoattractant when ECs are apically stimulated, which mimics the attenuated PMN chemotaxis seen in sepsis. Escalating the apical inflammatory stimulus by a factor of five is necessary to elicit high PMN transmigration levels across endothelium. These results demonstrate that EC apicobasal polarity modulates PMN transmigratory behavior and provides insight into the mechanisms underlying sepsis.
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Affiliation(s)
- Danial Ahmad
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
| | - Isabelle Linares
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
| | - Anthony Pietropaoli
- Department of Medicine, Pulmonary Diseases and Critical Care at the University of Rochester, Rochester, NY, 14627, USA
| | - Richard E Waugh
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
| | - James L McGrath
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
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3
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Moro M, Balestrero FC, Grolla AA. Pericytes: jack-of-all-trades in cancer-related inflammation. Front Pharmacol 2024; 15:1426033. [PMID: 39086395 PMCID: PMC11288921 DOI: 10.3389/fphar.2024.1426033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 06/25/2024] [Indexed: 08/02/2024] Open
Abstract
Pericytes, recognized as mural cells, have long been described as components involved in blood vessel formation, playing a mere supporting role for endothelial cells (ECs). Emerging evidence strongly suggests their multifaceted roles in tissues and organs. Indeed, pericytes exhibit a remarkable ability to anticipate endothelial cell behavior and adapt their functions based on the specific cells they interact with. Pericytes can be activated by pro-inflammatory stimuli and crosstalk with immune cells, actively participating in their transmigration into blood vessels. Moreover, they can influence the immune response, often sustaining an immunosuppressive phenotype in most of the cancer types studied. In this review, we concentrate on the intricate crosstalk between pericytes and immune cells in cancer, highlighting the primary evidence regarding pericyte involvement in primary tumor mass dynamics, their contributions to tumor reprogramming for invasion and migration of malignant cells, and their role in the formation of pre-metastatic niches. Finally, we explored recent and emerging pharmacological approaches aimed at vascular normalization, including novel strategies to enhance the efficacy of immunotherapy through combined use with anti-angiogenic drugs.
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Affiliation(s)
| | | | - Ambra A. Grolla
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, Italy
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4
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Carvalho TP, Toledo FAO, Bautista DFA, Silva MF, Oliveira JBS, Lima PA, Costa FB, Ribeiro NQ, Lee JY, Birbrair A, Paixão TA, Tsolis RM, Santos RL. Pericytes modulate endothelial inflammatory response during bacterial infection. mBio 2024; 15:e0325223. [PMID: 38289074 PMCID: PMC10936204 DOI: 10.1128/mbio.03252-23] [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: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 03/14/2024] Open
Abstract
Pericytes are located around blood vessels, in close contact with endothelial cells. We discovered that pericytes dampen pro-inflammatory endothelial cell responses. Endothelial cells co-cultured with pericytes had markedly reduced expression of adhesion molecules (PECAM-1 and ICAM-1) and proinflammatory cytokines (CCL-2 and IL-6) in response to bacterial stimuli (Brucella ovis, Listeria monocytogenes, or Escherichia coli lipopolysaccharide). Pericyte-depleted mice intraperitoneally inoculated with either B. ovis, a stealthy pathogen that does not trigger detectable inflammation, or Listeria monocytogenes, developed peritonitis. Further, during Citrobacter rodentium infection, pericyte-depleted mice developed severe intestinal inflammation, which was not evident in control mice. The anti-inflammatory effect of pericytes required connexin 43, as either chemical inhibition or silencing of connexin 43 abrogated pericyte-mediated suppression of endothelial inflammatory responses. Our results define a mechanism by which pericytes modulate inflammation during infection, which shifts our understanding of pericyte biology: from a structural cell to a pro-active player in modulating inflammation. IMPORTANCE A previously unknown mechanism by which pericytes modulate inflammation was discovered. The absence of pericytes or blocking interaction between pericytes and endothelium through connexin 43 results in stronger inflammation, which shifts our understanding of pericyte biology, from a structural cell to a player in controlling inflammation.
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Affiliation(s)
- Thaynara P. Carvalho
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
| | - Frank A. O. Toledo
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Diego F. A. Bautista
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Monique F. Silva
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Jefferson B. S. Oliveira
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Pâmela A. Lima
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Fabíola B. Costa
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Noelly Q. Ribeiro
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Jee-Yon Lee
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
| | - Alexander Birbrair
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Department of Dermatology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Tatiane A. Paixão
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Reneé M. Tsolis
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
| | - Renato L. Santos
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
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5
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Barnacle JR, Davis AG, Wilkinson RJ. Recent advances in understanding the human host immune response in tuberculous meningitis. Front Immunol 2024; 14:1326651. [PMID: 38264653 PMCID: PMC10803428 DOI: 10.3389/fimmu.2023.1326651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/18/2023] [Indexed: 01/25/2024] Open
Abstract
Tuberculous meningitis (TBM), the most severe form of tuberculosis, causes death in approximately 25% cases despite antibiotic therapy, and half of survivors are left with neurological disability. Mortality and morbidity are contributed to by a dysregulated immune response, and adjunctive host-directed therapies are required to modulate this response and improve outcomes. Developing such therapies relies on improved understanding of the host immune response to TBM. The historical challenges in TBM research of limited in vivo and in vitro models have been partially overcome by recent developments in proteomics, transcriptomics, and metabolomics, and the use of these technologies in nested substudies of large clinical trials. We review the current understanding of the human immune response in TBM. We begin with M. tuberculosis entry into the central nervous system (CNS), microglial infection and blood-brain and other CNS barrier dysfunction. We then outline the innate response, including the early cytokine response, role of canonical and non-canonical inflammasomes, eicosanoids and specialised pro-resolving mediators. Next, we review the adaptive response including T cells, microRNAs and B cells, followed by the role of the glutamate-GABA neurotransmitter cycle and the tryptophan pathway. We discuss host genetic immune factors, differences between adults and children, paradoxical reaction, and the impact of HIV-1 co-infection including immune reconstitution inflammatory syndrome. Promising immunomodulatory therapies, research gaps, ongoing challenges and future paths are discussed.
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Affiliation(s)
- James R. Barnacle
- The Francis Crick Institute, London, United Kingdom
- Department of Infectious Disease, Imperial College, London, United Kingdom
- Centre for Infectious Diseases Research in Africa, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory, South Africa
| | - Angharad G. Davis
- The Francis Crick Institute, London, United Kingdom
- Centre for Infectious Diseases Research in Africa, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory, South Africa
| | - Robert J. Wilkinson
- The Francis Crick Institute, London, United Kingdom
- Department of Infectious Disease, Imperial College, London, United Kingdom
- Centre for Infectious Diseases Research in Africa, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory, South Africa
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6
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Kulkarni A, Jozefiaková J, Bhide K, Mochnaćová E, Bhide M. Differential transcriptome response of blood brain barrier spheroids to neuroinvasive Neisseria and Borrelia. Front Cell Infect Microbiol 2023; 13:1326578. [PMID: 38179419 PMCID: PMC10766361 DOI: 10.3389/fcimb.2023.1326578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 11/30/2023] [Indexed: 01/06/2024] Open
Abstract
Background The blood-brain barrier (BBB), a highly regulated interface between the blood and the brain, prevents blood-borne substances and pathogens from entering the CNS. Nevertheless, pathogens like Neisseria meningitidis and Borrelia bavariensis can breach the BBB and infect the brain parenchyma. The self-assembling BBB-spheroids can simulate the cross talk occurring between the cells of the barrier and neuroinvasive pathogens. Methods BBB spheroids were generated by co-culturing human brain microvascular endothelial cells (hBMECs), pericytes and astrocytes. The BBB attributes of spheroids were confirmed by mapping the localization of cells, observing permeability of angiopep2 and non-permeability of dextran. Fluorescent Neisseria, Borrelia or E. coli (non-neuroinvasive) were incubated with spheroids to observe the adherence, invasion and spheroid integrity. Transcriptome analysis with NGS was employed to investigate the response of BBB cells to infections. Results hBMECs were localized throughout the spheroids, whereas pericytes and astrocytes were concentrated around the core. Within 1 hr of exposure, Neisseria and Borrelia adhered to spheroids, and their microcolonization increased from 5 to 24 hrs. Integrity of spheroids was compromised by both Neisseria and Borrelia, but not by E. coli infection. Transcriptome analysis revealed a significant change in the expression of 781 genes (467 up and 314 down regulated) in spheroids infected with Neisseria, while Borrelia altered the expression of 621 genes (225 up and 396 down regulated). The differentially expressed genes could be clustered into various biological pathways like cell adhesion, extracellular matrix related, metallothionines, members of TGF beta, WNT signaling, and immune response. Among the differentially expressed genes, 455 (48%) genes were inversely expressed during Neisseria and Borrelia infection. Conclusion The self-assembling spheroids were used to perceive the BBB response to neuroinvasive pathogens - Neisseria and Borrelia. Compromised integrity of spheroids during Neisseria and Borrelia infection as opposed to its intactness and non-adherence of E. coli (non-neuroinvasive) denotes the pathogen dependent fate of BBB. Genes categorized into various biological functions indicated weakened barrier properties of BBB and heightened innate immune response. Inverse expression of 48% genes commonly identified during Neisseria and Borrelia infection exemplifies unique response of BBB to varying neuropathogens.
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Affiliation(s)
- Amod Kulkarni
- Laboratory of Biomedical Microbiology and Immunology, The University of Veterinary Medicine and Pharmacy, Kosice, Slovakia
- Institute of Neuroimmunology of Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jana Jozefiaková
- Laboratory of Biomedical Microbiology and Immunology, The University of Veterinary Medicine and Pharmacy, Kosice, Slovakia
| | - Katarína Bhide
- Laboratory of Biomedical Microbiology and Immunology, The University of Veterinary Medicine and Pharmacy, Kosice, Slovakia
| | - Evelína Mochnaćová
- Laboratory of Biomedical Microbiology and Immunology, The University of Veterinary Medicine and Pharmacy, Kosice, Slovakia
| | - Mangesh Bhide
- Laboratory of Biomedical Microbiology and Immunology, The University of Veterinary Medicine and Pharmacy, Kosice, Slovakia
- Institute of Neuroimmunology of Slovak Academy of Sciences, Bratislava, Slovakia
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7
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Teske NC, Dyckhoff-Shen S, Beckenbauer P, Bewersdorf JP, Engelen-Lee JY, Hammerschmidt S, Kälin RE, Pfister HW, Brouwer MC, Klein M, Glass R, van de Beek D, Koedel U. Pericytes are protective in experimental pneumococcal meningitis through regulating leukocyte infiltration and blood-brain barrier function. J Neuroinflammation 2023; 20:267. [PMID: 37978545 PMCID: PMC10655320 DOI: 10.1186/s12974-023-02938-z] [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: 07/16/2023] [Accepted: 10/27/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND Brain pericytes participate in the regulation of cerebral blood flow and the maintenance of blood-brain barrier integrity. Because of their perivascular localization, their receptor repertoire, and their potential ability to respond to inflammatory and infectious stimuli by producing various cytokines and chemokines, these cells are also thought to play an active role in the immune response to brain infections. This assumption is mainly supported by in vitro studies, investigations in in vivo disease models are largely missing. Here, we analysed the role of brain pericytes in pneumococcal meningitis, in vitro and in vivo in two animal models of pneumococcal meningitis. METHODS Primary murine and human pericytes were stimulated with increasing concentrations of different serotypes of Streptococcus pneumoniae in the presence or absence of Toll-like receptor inhibitors and their cell viability and cytokine production were monitored. To gain insight into the role of pericytes in brain infection in vivo, we performed studies in a zebrafish embryo model of pneumococcal meningitis in which pericytes were pharmacologically depleted. Furthermore, we analyzed the impact of genetically induced pericyte ablation on disease progression, intracranial complications, and brain inflammation in an adult mouse model of this disease. RESULTS Both murine and human pericytes reacted to pneumococcal exposure with the release of selected cytokines. This cytokine release is pneumolysin-dependent, TLR-dependent in murine (but not human) pericytes and can be significantly increased by macrophage-derived IL-1b. Pharmacological depletion of pericytes in zebrafish embryos resulted in increased cerebral edema and mortality due to pneumococcal meningitis. Correspondingly, in an adult mouse meningitis model, a more pronounced blood-brain barrier disruption and leukocyte infiltration, resulting in an unfavorable disease course, was observed following genetic pericyte ablation. The degree of leukocyte infiltration positively correlated with an upregulation of chemokine expression in the brains of pericyte-depleted mice. CONCLUSIONS Our findings show that pericytes play a protective role in pneumococcal meningitis by impeding leukocyte migration and preventing blood-brain barrier breaching. Thus, preserving the integrity of the pericyte population has the potential as a new therapeutic strategy in pneumococcal meningitis.
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Affiliation(s)
- Nina C Teske
- Department of Neurology, LMU University Hospital, LMU Munich, Munich, Germany.
- ESCMID Study Group for Infections of the Brain, Basel, Switzerland.
- Department of Neurology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands.
- Department of Neurosurgery, LMU University Hospital, LMU Munich, Munich, Germany.
| | | | - Paul Beckenbauer
- Department of Neurology, LMU University Hospital, LMU Munich, Munich, Germany
| | | | - Joo-Yeon Engelen-Lee
- ESCMID Study Group for Infections of the Brain, Basel, Switzerland
- Department of Neurology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Sven Hammerschmidt
- Department Genetics of Microorganisms, Interfaculty Institute of Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - Roland E Kälin
- Neurosurgical Research, Department of Neurosurgery, LMU University Hospital, LMU Munich, Munich, Germany
- Walter Brendel Center of Experimental Medicine, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Hans-Walter Pfister
- Department of Neurology, LMU University Hospital, LMU Munich, Munich, Germany
- ESCMID Study Group for Infections of the Brain, Basel, Switzerland
| | - Matthijs C Brouwer
- ESCMID Study Group for Infections of the Brain, Basel, Switzerland
- Department of Neurology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Matthias Klein
- Department of Neurology, LMU University Hospital, LMU Munich, Munich, Germany
- ESCMID Study Group for Infections of the Brain, Basel, Switzerland
| | - Rainer Glass
- Neurosurgical Research, Department of Neurosurgery, LMU University Hospital, LMU Munich, Munich, Germany
| | - Diederik van de Beek
- ESCMID Study Group for Infections of the Brain, Basel, Switzerland
- Department of Neurology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Uwe Koedel
- Department of Neurology, LMU University Hospital, LMU Munich, Munich, Germany
- ESCMID Study Group for Infections of the Brain, Basel, Switzerland
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The Role of Pericytes in Regulation of Innate and Adaptive Immunity. Biomedicines 2023; 11:biomedicines11020600. [PMID: 36831136 PMCID: PMC9953719 DOI: 10.3390/biomedicines11020600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 02/03/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Pericytes are perivascular multipotent cells wrapping microvascular capillaries, where they support vasculature functioning, participate in tissue regeneration, and regulate blood flow. However, recent evidence suggests that in addition to traditionally credited structural function, pericytes also manifest immune properties. In this review, we summarise recent data regarding pericytes' response to different pro-inflammatory stimuli and their involvement in innate immune responses through expression of pattern-recognition receptors. Moreover, pericytes express various adhesion molecules, thus regulating trafficking of immune cells across vessel walls. Additionally, the role of pericytes in modulation of adaptive immunity is discussed. Finally, recent reports have suggested that the interaction with cancer cells evokes immunosuppression function in pericytes, thus facilitating immune evasion and facilitating cancer proliferation and metastasis. However, such complex and multi-faceted cross-talks of pericytes with immune cells also suggest a number of potential pericyte-based therapeutic methods and techniques for cancer immunotherapy and treatment of autoimmune and auto-inflammatory disorders.
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Gil E, Wall E, Noursadeghi M, Brown JS. Streptococcus pneumoniae meningitis and the CNS barriers. Front Cell Infect Microbiol 2023; 12:1106596. [PMID: 36683708 PMCID: PMC9845635 DOI: 10.3389/fcimb.2022.1106596] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/08/2022] [Indexed: 01/05/2023] Open
Abstract
Streptococcus pneumoniae (SPN) is a globally significant cause of meningitis, the pathophysiology of which involves damage to the brain by both bacterial virulence factors and the host inflammatory response. In most cases of SPN meningitis bacteria translocate from the blood into the central nervous system (CNS). The principal site of SPN translocation into the CNS is not known, with possible portals of entry proposed to be the cerebral or meningeal blood vessels or the choroid plexus. All require SPN to bind to and translocate across the vascular endothelial barrier, and subsequently the basement membrane and perivascular structures, including an additional epithelial barrier in the case of the blood-CSF barrier. The presence of SPN in the CNS is highly inflammatory resulting in marked neutrophilic infiltration. The secretion of toxic inflammatory mediators by activated neutrophils within the CNS damages pathogen and host alike, including the non-replicative neurons which drives morbidity and mortality. As with the translocation of SPN, the recruitment of neutrophils into the CNS in SPN meningitis necessitates the translocation of neutrophils from the circulation across the vascular barrier, a process that is tightly regulated under basal conditions - a feature of the 'immune specialization' of the CNS. The brain barriers are therefore central to SPN meningitis, both through a failure to exclude bacteria and maintain CNS sterility, and subsequently through the active recruitment and/or failure to exclude circulating leukocytes. The interactions of SPN with these barriers, barrier inflammatory responses, along with their therapeutic implications, are explored in this review.
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Affiliation(s)
- Eliza Gil
- Division of Infection and Immunity, University College London, London, United Kingdom,*Correspondence: Eliza Gil,
| | - Emma Wall
- Francis Crick Institute, London, United Kingdom,UCLH Biomedical Research Centre, London, United Kingdom
| | - Mahdad Noursadeghi
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Jeremy S. Brown
- Division of Medicine, University College London, London, United Kingdom
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