Limits...
Lipopolysaccharide modulates astrocytic S100B secretion: a study in cerebrospinal fluid and astrocyte cultures from rats.

Guerra MC, Tortorelli LS, Galland F, Da Ré C, Negri E, Engelke DS, Rodrigues L, Leite MC, Gonçalves CA - J Neuroinflammation (2011)

Bottom Line: However, lower levels of LPS in astrocyte cultures were able to induce a decrease in S100B secretion after 24 h, without significant change in intracellular content of S100B.Together, these data contribute to the understanding of the effects of LPS on astrocytes, particularly on S100B secretion, and help us to interpret cerebrospinal fluid and serum changes for this protein in neuroinflammatory diseases.Moreover, non-brain S100B-expressing tissues may be differentially regulated, since LPS administration did not lead to increased serum levels of S100B.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos, Porto Alegre, Brazil.

ABSTRACT

Background: Inflammatory responses in brain are primarily mediated by microglia, but growing evidence suggests a crucial importance of astrocytes. S100B, a calcium-binding protein secreted by astrocytes, has properties of a neurotrophic or an inflammatory cytokine. However, it is not known whether primary signals occurring during induction of an inflammatory response (e.g. lipopolysaccharide, LPS) directly modulate S100B.

Methods: In this work, we evaluated whether S100B levels in cerebrospinal fluid (CSF) and serum of Wistar rats are affected by LPS administered by intraperitoneal (IP) or intracerebroventricular (ICV) injection, as well as whether primary astrocyte cultures respond directly to lipopolysaccharide.

Results: Our data suggest that S100B secretion in brain tissue is stimulated rapidly and persistently (for at least 24 h) by ICV LPS administration. This increase in CSF S100B was transient when LPS was IP administered. In contrast to these S100B results, we observed an increase in in TNFα levels in serum, but not in CSF, after IP administration of LPS. In isolated astrocytes and in acute hippocampal slices, we observed a direct stimulation of S100B secretion by LPS at a concentration of 10 μg/mL. An involvement of TLR4 was confirmed by use of specific inhibitors. However, lower levels of LPS in astrocyte cultures were able to induce a decrease in S100B secretion after 24 h, without significant change in intracellular content of S100B. In addition, after 24 h exposure to LPS, we observed a decrease in astrocytic glutathione and an increase in astrocytic glial fibrillary acidic protein.

Conclusions: Together, these data contribute to the understanding of the effects of LPS on astrocytes, particularly on S100B secretion, and help us to interpret cerebrospinal fluid and serum changes for this protein in neuroinflammatory diseases. Moreover, non-brain S100B-expressing tissues may be differentially regulated, since LPS administration did not lead to increased serum levels of S100B.

Show MeSH

Related in: MedlinePlus

LPS induces increased levels of S100B in cerebrospinal fluid (CSF), but not in serum. Intracerebroventricular injection of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, cerebrospinal fluid was collected by magna puncture (A) and blood by intracardic puncture (B). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. Intraperitoneal infusion of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, CSF was collected by magna puncture (C) and blood by intracardic puncture (D). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. * Significantly different from respective control (Student t test, p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3198930&req=5

Figure 1: LPS induces increased levels of S100B in cerebrospinal fluid (CSF), but not in serum. Intracerebroventricular injection of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, cerebrospinal fluid was collected by magna puncture (A) and blood by intracardic puncture (B). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. Intraperitoneal infusion of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, CSF was collected by magna puncture (C) and blood by intracardic puncture (D). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. * Significantly different from respective control (Student t test, p < 0.05).

Mentions: Anesthetized adult rats received 10 μL ICV of 2.5 μg/μL LPS or phosphate-buffered saline (control). CSF and blood were collected at 30 min or 24 h after LPS administration. A significant increase in CSF S100B was observed at 30 min (p = 0.009) and 24 h (p = 0.003) (Figure 1A), without significant changes in S100B serum content (p = 0.99, 30 min and p = 0.47, 24 h) (Figure 1B). Interestingly, when rats received IP LPS (250 μg/Kg body) they also exhibited an increase in CSF S100B at 30 min (p = 0.007), but not at 24 h (p = 0.68) (Figure 1C), and again no significant changes in serum S100B were observed when compared with controls that received phosphate-buffered saline (p = 0.28, 30 min and p = 0.32, 24 h) (Figure 1D). Notice that, assuming a mean body weight of rats of 0.3 Kg, the amount of LPS administered IP and ICV was 75 and 25 μg, respectively.


Lipopolysaccharide modulates astrocytic S100B secretion: a study in cerebrospinal fluid and astrocyte cultures from rats.

Guerra MC, Tortorelli LS, Galland F, Da Ré C, Negri E, Engelke DS, Rodrigues L, Leite MC, Gonçalves CA - J Neuroinflammation (2011)

LPS induces increased levels of S100B in cerebrospinal fluid (CSF), but not in serum. Intracerebroventricular injection of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, cerebrospinal fluid was collected by magna puncture (A) and blood by intracardic puncture (B). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. Intraperitoneal infusion of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, CSF was collected by magna puncture (C) and blood by intracardic puncture (D). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. * Significantly different from respective control (Student t test, p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198930&req=5

Figure 1: LPS induces increased levels of S100B in cerebrospinal fluid (CSF), but not in serum. Intracerebroventricular injection of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, cerebrospinal fluid was collected by magna puncture (A) and blood by intracardic puncture (B). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. Intraperitoneal infusion of LPS, or saline solution, was carried out in adult Wistar rats under anaesthesia. After 30 min or 24 h, CSF was collected by magna puncture (C) and blood by intracardic puncture (D). The control group is represented by grey bars and the LPS-treated group is represented by open bars. Each value is a mean (± standard error) from 5 rats per group. * Significantly different from respective control (Student t test, p < 0.05).
Mentions: Anesthetized adult rats received 10 μL ICV of 2.5 μg/μL LPS or phosphate-buffered saline (control). CSF and blood were collected at 30 min or 24 h after LPS administration. A significant increase in CSF S100B was observed at 30 min (p = 0.009) and 24 h (p = 0.003) (Figure 1A), without significant changes in S100B serum content (p = 0.99, 30 min and p = 0.47, 24 h) (Figure 1B). Interestingly, when rats received IP LPS (250 μg/Kg body) they also exhibited an increase in CSF S100B at 30 min (p = 0.007), but not at 24 h (p = 0.68) (Figure 1C), and again no significant changes in serum S100B were observed when compared with controls that received phosphate-buffered saline (p = 0.28, 30 min and p = 0.32, 24 h) (Figure 1D). Notice that, assuming a mean body weight of rats of 0.3 Kg, the amount of LPS administered IP and ICV was 75 and 25 μg, respectively.

Bottom Line: However, lower levels of LPS in astrocyte cultures were able to induce a decrease in S100B secretion after 24 h, without significant change in intracellular content of S100B.Together, these data contribute to the understanding of the effects of LPS on astrocytes, particularly on S100B secretion, and help us to interpret cerebrospinal fluid and serum changes for this protein in neuroinflammatory diseases.Moreover, non-brain S100B-expressing tissues may be differentially regulated, since LPS administration did not lead to increased serum levels of S100B.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos, Porto Alegre, Brazil.

ABSTRACT

Background: Inflammatory responses in brain are primarily mediated by microglia, but growing evidence suggests a crucial importance of astrocytes. S100B, a calcium-binding protein secreted by astrocytes, has properties of a neurotrophic or an inflammatory cytokine. However, it is not known whether primary signals occurring during induction of an inflammatory response (e.g. lipopolysaccharide, LPS) directly modulate S100B.

Methods: In this work, we evaluated whether S100B levels in cerebrospinal fluid (CSF) and serum of Wistar rats are affected by LPS administered by intraperitoneal (IP) or intracerebroventricular (ICV) injection, as well as whether primary astrocyte cultures respond directly to lipopolysaccharide.

Results: Our data suggest that S100B secretion in brain tissue is stimulated rapidly and persistently (for at least 24 h) by ICV LPS administration. This increase in CSF S100B was transient when LPS was IP administered. In contrast to these S100B results, we observed an increase in in TNFα levels in serum, but not in CSF, after IP administration of LPS. In isolated astrocytes and in acute hippocampal slices, we observed a direct stimulation of S100B secretion by LPS at a concentration of 10 μg/mL. An involvement of TLR4 was confirmed by use of specific inhibitors. However, lower levels of LPS in astrocyte cultures were able to induce a decrease in S100B secretion after 24 h, without significant change in intracellular content of S100B. In addition, after 24 h exposure to LPS, we observed a decrease in astrocytic glutathione and an increase in astrocytic glial fibrillary acidic protein.

Conclusions: Together, these data contribute to the understanding of the effects of LPS on astrocytes, particularly on S100B secretion, and help us to interpret cerebrospinal fluid and serum changes for this protein in neuroinflammatory diseases. Moreover, non-brain S100B-expressing tissues may be differentially regulated, since LPS administration did not lead to increased serum levels of S100B.

Show MeSH
Related in: MedlinePlus