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Role of astroglial Connexin 43 in pneumolysin cytotoxicity and during pneumococcal meningitis. PLoS Pathog 2020; 16:e1009152. [PMID: 33370401 PMCID: PMC7793270 DOI: 10.1371/journal.ppat.1009152] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 01/08/2021] [Accepted: 11/11/2020] [Indexed: 12/19/2022] Open
Abstract
Streptococcus pneumoniae or pneumococcus (PN) is a major causative agent of bacterial meningitis with high mortality in young infants and elderly people worldwide. The mechanism underlying PN crossing of the blood brain barrier (BBB) and specifically, the role of non-endothelial cells of the neurovascular unit that control the BBB function, remains poorly understood. Here, we show that the astroglial connexin 43 (aCx43), a major gap junctional component expressed in astrocytes, plays a predominant role during PN meningitis. Following intravenous PN challenge, mice deficient for aCx43 developed milder symptoms and showed severely reduced bacterial counts in the brain. Immunofluorescence analysis of brain slices indicated that PN induces the aCx43–dependent destruction of the network of glial fibrillary acid protein (GFAP), an intermediate filament protein specifically expressed in astrocytes and up-regulated in response to brain injury. PN also induced nuclear shrinkage in astrocytes associated with the loss of BBB integrity, bacterial translocation across endothelial vessels and replication in the brain cortex. We found that aCx4-dependent astrocyte damages could be recapitulated using in vitro cultured cells upon challenge with wild-type PN but not with a ply mutant deficient for the pore-forming toxin pneumolysin (Ply). Consistently, we showed that purified Ply requires Cx43 to promote host cell plasma membrane permeabilization in a process involving the Cx43-dependent release of extracellular ATP and prolonged increase of cytosolic Ca2+ in host cells. These results point to a critical role for astrocytes during PN meningitis and suggest that the cytolytic activity of the major virulence factor Ply at concentrations relevant to bacterial infection requires co-opting of connexin plasma membrane channels. The role of non-endothelial cells constituting the neurovascular unit during infectious meningitis is poorly appreciated despite their key regulatory functions on the blood-brain barrier integrity. Here, we show that Streptococcus pneumoniae or pneumococcus, a major causative agent of bacterial meningitis, targets astroglial cells to translocate across brain endothelial vessels. We found that astroglial connexin 43, a gap junctional component, played a major role during PN meningitis in mice. PN translocation and replication in the brain cortex were associated with connexin-dependent fragmentation of astrocytic the GFAP network, a process associated with brain injury. These findings were recapitulated and extended in vitro using cultured primary astrocytes and the major PN virulence determinant Pneumolysin. Ply-mediated cytotoxicity was linked to Ca2+ increase and required aCx43, arguing against a direct toxin activity. The results reveal a key role for astroglial signaling during PN crossing of the BBB and shed light on the mechanism of Ply-mediated cytotoxicity during meningitis.
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Leal Denis MF, Lefevre SD, Alvarez CL, Lauri N, Enrique N, Rinaldi DE, Gonzalez-Lebrero R, Vecchio LE, Espelt MV, Stringa P, Muñoz-Garay C, Milesi V, Ostuni MA, Herlax V, Schwarzbaum PJ. Regulation of extracellular ATP of human erythrocytes treated with α-hemolysin. Effects of cell volume, morphology, rheology and hemolysis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:896-915. [PMID: 30726708 DOI: 10.1016/j.bbamcr.2019.01.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/10/2019] [Accepted: 01/30/2019] [Indexed: 12/17/2022]
Abstract
Alpha-hemolysin (HlyA) of uropathogenic strains of Escherichia coli irreversibly binds to human erythrocytes (RBCs) and triggers activation of ATP release and metabolic changes ultimately leading to hemolysis. We studied the regulation of extracellular ATP (ATPe) of RBCs exposed to HlyA. Luminometry was used to assess ATP release and ATPe hydrolysis, whereas changes in cell volume and morphology were determined by electrical impedance, ektacytometry and aggregometry. Exposure of RBCs to HlyA induced a strong increase of [ATPe] (3-36-fold) and hemolysis (1-44-fold), partially compensated by [ATPe] hydrolysis by ectoATPases and intracellular ATPases released by dead cells. Carbenoxolone, a pannexin 1 inhibitor, partially inhibited ATP release (43-67%). The un-acylated toxin ProHlyA and the deletion analog HlyA∆914-936 were unable to induce ATP release or hemolysis. For HlyA treated RBCs, a data driven mathematical model showed that simultaneous lytic and non-lytic release mainly governed ATPe kinetics, while ATPe hydrolysis became important after prolonged toxin exposure. HlyA induced a 1.5-fold swelling, while blocking this swelling reduced ATP release by 77%. Blocking ATPe activation of purinergic P2X receptors reduced swelling by 60-80%. HlyA-RBCs showed an acute 1.3-2.2-fold increase of Ca2+i, increased crenation and externalization of phosphatidylserine. Perfusion of HlyA-RBCs through adhesion platforms showed strong adhesion to activated HMEC cells, followed by rapid detachment. HlyA exposed RBCs exhibited increased sphericity under osmotic stress, reduced elongation under shear stress, and very low aggregation in viscous media. Overall results showed that HlyA-RBCs displayed activated ATP release, high but weak adhesivity, low deformability and aggregability and high sphericity.
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Affiliation(s)
- M F Leal Denis
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini", Facultad de Farmacia y Bioquímica, Junín 956 Buenos Aires, Argentina.; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Analítica, Cátedra de Química Química Analítica y Fisicoquímica, Junín 956 Buenos Aires, Argentina
| | - S D Lefevre
- UMR-S1134, Integrated Biology of Red Blood Cells, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Université de la Réunion, Université des Antilles, F-75015 Paris, France.; Institut National de la Transfusion Sanguine, Laboratoire d'Excellence GR-Ex, F-75015 Paris, France
| | - C L Alvarez
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini", Facultad de Farmacia y Bioquímica, Junín 956 Buenos Aires, Argentina.; Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Intendente Güiraldes 2160 Buenos Aires, Argentina
| | - N Lauri
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini", Facultad de Farmacia y Bioquímica, Junín 956 Buenos Aires, Argentina.; Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Biológica. Cátedra de Química Biológica Superior, Junín 956 Buenos Aires, Argentina
| | - N Enrique
- Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Facultad de Ciencias Exactas, Calle 47 y 115 La Plata, Argentina.; Universidad Nacional de la Plata, Facultad de Ciencias Exactas, Departamento de Ciencias Biológicas, Cátedra de Fisiología, Calle 47, Casco Urbano, La Plata, Argentina
| | - D E Rinaldi
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini", Facultad de Farmacia y Bioquímica, Junín 956 Buenos Aires, Argentina.; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956 Buenos Aires, Argentina
| | - R Gonzalez-Lebrero
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini", Facultad de Farmacia y Bioquímica, Junín 956 Buenos Aires, Argentina.; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956 Buenos Aires, Argentina
| | - L E Vecchio
- Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Facultad de Ciencias Exactas, Calle 47 y 115 La Plata, Argentina.; Universidad Nacional de la Plata, Facultad de Ciencias Exactas, Departamento de Ciencias Biológicas, Cátedra de Fisiología, Calle 47, Casco Urbano, La Plata, Argentina
| | - M V Espelt
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini", Facultad de Farmacia y Bioquímica, Junín 956 Buenos Aires, Argentina.; Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Biológica. Cátedra de Química Biológica Superior, Junín 956 Buenos Aires, Argentina
| | - P Stringa
- Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Facultad de Ciencias Exactas, Calle 47 y 115 La Plata, Argentina.; Universidad Favaloro, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Medicina Traslacional, Trasplante y Bioingeniería (IMETTyB), Av. Entre Ríos 495, Buenos Aires, Argentina.; Universidad Nacional de La Plata, Laboratorio de Trasplante de Órganos y Tejidos, Facultad de Ciencias, Calle 60 y 120, La Plata, Argentina
| | - C Muñoz-Garay
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México (UNAM), Av. Universidad s/n, Cuernavaca, Mexico
| | - V Milesi
- Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Facultad de Ciencias Exactas, Calle 47 y 115 La Plata, Argentina.; Universidad Nacional de la Plata, Facultad de Ciencias Exactas, Departamento de Ciencias Biológicas, Cátedra de Fisiología, Calle 47, Casco Urbano, La Plata, Argentina
| | - M A Ostuni
- UMR-S1134, Integrated Biology of Red Blood Cells, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Université de la Réunion, Université des Antilles, F-75015 Paris, France.; Institut National de la Transfusion Sanguine, Laboratoire d'Excellence GR-Ex, F-75015 Paris, France
| | - V Herlax
- Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP) "Prof. Dr. Rodolfo R. Brenner", Facultad de Ciencias Médicas, Av. 60 y Av. 120, La Plata, Argentina.; Universidad Nacional de La Plata, Facultad de Ciencias Médicas, Av. 60 y Av. 120, La Plata, Argentina
| | - P J Schwarzbaum
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini", Facultad de Farmacia y Bioquímica, Junín 956 Buenos Aires, Argentina.; Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Biológica. Cátedra de Química Biológica Superior, Junín 956 Buenos Aires, Argentina..
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