The inflammatory response and neuronal injury in Streptococcus suis meningitis

Seele, Jana; Tauber, Simone C.; Bunkowski, Stephanie; Baums, Christoph Georg; Valentin‐Weigand, Peter; Buhr, Nicole de; Beineke, Andreas; Iliev, Alexandar; Brück, Wolfgang; Nau, Roland

doi:10.1186/s12879-018-3206-6

Cited by 8 publications

(9 citation statements)

References 64 publications

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“…Following systemic infection, surviving individuals are susceptible to developing a life-threatening CNS disease (3,4), during which infiltration of monocytes and neutrophils has been well documented (2,3,8,21). S. suis-induced meningitis is classified as suppurative, indicating a predominance of neutrophils, which concurs with results obtained in this study, accompanied by inflammatory, but few patrolling, monocytes.…”

Section: Discussionsupporting

confidence: 90%

“…Following the acute S. suis systemic infection, surviving individuals are susceptible to developing a CNS disease of which meningitis is the hallmark (3,4). This disease is characterized by an exacerbated local inflammatory response in the CNS, activation of local resident CNS immune cells, and infiltration of peripheral immune cells, namely, monocytes and neutrophils (9,21,35). Moreover, this inflammatory response is composed not only of proinflammatory cytokines, but also of chemokines, which might participate in the recruitment and/or amplification of monocytes and neutrophils (4).…”

Section: Resultsmentioning

confidence: 99%

“…Inflammatory monocytes and neutrophils infiltrate the brain during S. suisinduced CNS disease. Though monocytes and neutrophils have been observed in CNS lesions of animals following S. suis infection using histology (2,3,8,21), the proportions of these cell types have not been determined before. Consequently, infiltrating brain monocyte and neutrophil populations (CD45 hi CD11b hi ) were quantified by flow cytometry upon presentation of S. suis-induced clinical CNS disease in wild-type mice.…”

Section: Resultsmentioning

confidence: 99%

“…In fact, resident CNS cells, probably microglia and astrocytes, would be mainly responsible for not only the local inflammation but also clinical disease. Resident CNS cells have not only been previously shown to produce IL-6, CCL2, and CXCL1 following S. suis infection in vitro (21,44,45), but they are also associated with CCL2 expression in vivo (3). Since it has been previously reported that depletion of both inflammatory monocytes and neutrophils resulted in a nearly complete absence of clinical CNS disease following S. pneumoniae or E. coli infection (31,32), the present study is the first to report no critical role of either infiltrating inflammatory monocytes or neutrophils in the development of bacterial meningitis.…”

Section: Discussionmentioning

confidence: 99%

“…However, not only are monocytes and neutrophils the main phagocytes in blood (18), but they are also sources of proinflammatory mediators and play important roles during bacterial infection (19,20). Moreover, S. suis-induced meningitis is characterized by an infiltration of these cells into the CNS (2,3,8,21). However, their role during S. suis-induced systemic and CNS diseases has been little studied.…”

mentioning

confidence: 99%

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Inflammatory Monocytes and Neutrophils Regulate Streptococcus suis-Induced Systemic Inflammation and Disease but Are Not Critical for the Development of Central Nervous System Disease in a Mouse Model of Infection

et al. 2020

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Streptococcus suis is an important porcine bacterial pathogen and zoonotic agent responsible for sudden death, septic shock, and meningitis. These pathologies are a consequence of elevated bacterial replication leading to exacerbated and uncontrolled inflammation, a hallmark of the S. suis systemic and central nervous system (CNS) infections. Monocytes and neutrophils are immune cells involved in various functions, including proinflammatory mediator production. Moreover, monocytes are composed of two main subsets: shorter-lived inflammatory monocytes and longer-lived patrolling monocytes. However, regardless of their presence in blood and the fact that S. suis-induced meningitis is characterized by infiltration of monocytes and neutrophils into the CNS, their role during the S. suis systemic and CNS diseases remains unknown. Consequently, we hypothesized that monocytes and neutrophils participate in S. suis infection via bacterial clearance and inflammation. Results demonstrated that inflammatory monocytes and neutrophils regulate S. suis-induced systemic disease via their role in inflammation required for bacterial burden control. In the CNS, inflammatory monocytes contributed to exacerbation of S. suis-induced local inflammation, while neutrophils participated in bacterial burden control. However, development of clinical CNS disease was independent of both cell types, indicating that resident immune cells are mostly responsible for S. suis-induced CNS inflammation and clinical disease and that inflammatory monocyte and neutrophil infiltration is a consequence of the induced inflammation. In contrast, the implication of patrolling monocytes was minimal throughout the S. suis infection. Consequently, this study demonstrates that while inflammatory monocytes and neutrophils modulate S. suis-induced systemic inflammation and disease, they are not critical for CNS disease development.

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