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by claude@2026-07, 2026-07-05
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The paper studied bioengineered human HEK293T-derived extracellular vesicles (EVs) as adjunct therapy for experimental pneumococcal meningitis, using wild-type EVs and EV variants expressing RVG peptides for neuronal targeting, IL-6 signal transducer decoy receptors to block IL-6–mediated inflammatory signaling, or both. In vitro, all EV preparations reduced pneumococcal adhesion to neurons and mitigated cytotoxicity by binding and sequestering pneumolysin (Ply), and in a bacteremia-derived mouse meningitis model EV treatment increased survival without changing bacterial load in the brain or periphery; RVG.EV most strongly reduced pro-inflammatory cytokine release in both compartments. The authors frame a key limitation as the limited brain delivery of standard antibiotics and the lack of antimicrobials capable of neutralizing Ply, and they report efficacy measured in an animal model rather than clinical outcomes. This paper does not explicitly discuss endometriosis or adenomyosis; it was included in the corpus via a keyword match in the upstream search index.
Abstract
Bacterial meningitis is a life-threatening neurological disorder frequently caused by a Streptococcus pneumoniae (the pneumococcus) infection of the brain. Standard treatment consists of antibiotics to eliminate bacteria and dexamethasone to reduce inflammation. Despite this, mortality reaches 20% in treated individuals, and half of the survivors suffer long-term neurological sequelae. This is largely due to the poor capacity of antibiotics to reach the brain and the lack of antimicrobial treatment capable of neutralizing the pneumococcal toxin pneumolysin (Ply). To address these limitations, we isolated extracellular vesicles (EVs) derived from human HEK293T cells and evaluated their therapeutic potential in pneumococcal meningitis. Alongside wild-type EVs (WT.EVs), we bioengineered EVs to express RVG peptides (RVG.EV) for targeting neuronal acetylcholine receptors, signal incompetent IL-6 signal transducer (IL-6ST) decoy receptors (IL-6.EV) to block the pro-inflammatory signalling of IL-6, or EVs expressing both RVG peptides and IL-6ST (DB.EV). In vitro, all EVs reduced pneumococcal adhesion to neurons and mitigated cytotoxicity by binding and sequestering Ply. In a bacteremia-derived pneumococcal meningitis model, EV treatment significantly increased the survival of the mice without affecting bacterial load in the brain or the periphery. Among all groups, RVG.EV treatment was most effective in reducing pro-inflammatory cytokine release in the periphery and brain. These findings highlight the therapeutic potential of bioengineered EVs, particularly RVG peptides expressing EVs, as an adjunctive treatment for pneumococcal meningitis thanks to their (i) sequestration and neutralization of Ply, (ii) increased blood-brain barrier crossing, and (iii) dampening of inflammation.
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Abstract
Bacterial meningitis is a life-threatening neurological disorder frequently caused by a Streptococcus pneumoniae (the pneumococcus) infection of the brain. Standard treatment consists of antibiotics to eliminate bacteria and dexamethasone to reduce inflammation. Despite this, mortality reaches 20% in treated individuals, and half of the survivors suffer long-term neurological sequelae. This is largely due to the poor capacity of antibiotics to reach the brain and the lack of antimicrobial treatment capable of neutralizing the pneumococcal toxin pneumolysin (Ply). To address these limitations, we isolated extracellular vesicles (EVs) derived from human HEK293T cells and evaluated their therapeutic potential in pneumococcal meningitis. Alongside wild-type EVs (WT.EVs), we bioengineered EVs to express RVG peptides (RVG.EV) for targeting neuronal acetylcholine receptors, signal incompetent IL-6 signal transducer (IL-6ST) decoy receptors (IL-6.EV) to block the pro-inflammatory signalling of IL-6, or EVs expressing both RVG peptides and IL-6ST (DB.EV). In vitro, all EVs reduced pneumococcal adhesion to neurons and mitigated cytotoxicity by binding and sequestering Ply. In a bacteremia-derived pneumococcal meningitis model, EV treatment significantly increased the survival of the mice without affecting bacterial load in the brain or the periphery. Among all groups, RVG.EV treatment was most effective in reducing pro-inflammatory cytokine release in the periphery and brain. These findings highlight the therapeutic potential of bioengineered EVs, particularly RVG peptides expressing EVs, as an adjunctive treatment for pneumococcal meningitis thanks to their (i) sequestration and neutralization of Ply, (ii) increased blood-brain barrier crossing, and (iii) dampening of inflammation.
Competing Interest Statement
Oscar P. B. Wiklander and Samir El-Andaloussi hold stock interests in Evox Therapeutics. Samir El-Andaloussi is also the founder. The other authors declare no competing interests.
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