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Quinolinic acid toxicity on oligodendroglial cells: relevance for multiple sclerosis and therapeutic strategies.

Sundaram G, Brew BJ, Jones SP, Adams S, Lim CK, Guillemin GJ - J Neuroinflammation (2014)

Bottom Line: Our group has also found pathophysiological concentrations of quinolinic acid in MS patients.This led us to investigate the effect of quinolinic acid on oligodendrocytes; the main cell type targeted by the autoimmune response in MS.We further propose and demonstrate two strategies to limit quinolinic acid gliotoxicity: 1) by neutralizing quinolinic acid's effects with anti-quinolinic acid monoclonal antibodies and 2) directly inhibiting quinolinic acid production from activated monocytic cells using specific KP enzyme inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia. g.sundaram@amr.org.au.

ABSTRACT
The excitotoxin quinolinic acid, a by-product of the kynurenine pathway, is known to be involved in several neurological diseases including multiple sclerosis (MS). Quinolinic acid levels are elevated in experimental autoimmune encephalomyelitis rodents, the widely used animal model of MS. Our group has also found pathophysiological concentrations of quinolinic acid in MS patients. This led us to investigate the effect of quinolinic acid on oligodendrocytes; the main cell type targeted by the autoimmune response in MS. We have examined the kynurenine pathway (KP) profile of two oligodendrocyte cell lines and show that these cells have a limited threshold to catabolize exogenous quinolinic acid. We further propose and demonstrate two strategies to limit quinolinic acid gliotoxicity: 1) by neutralizing quinolinic acid's effects with anti-quinolinic acid monoclonal antibodies and 2) directly inhibiting quinolinic acid production from activated monocytic cells using specific KP enzyme inhibitors. The outcome of this study provides a new insight into therapeutic strategies for limiting quinolinic acid-induced neurodegeneration, especially in neurological disorders that target oligodendrocytes, such as MS.

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Neutralization of exogenous quinolinic acid (QUIN) with an anti-QUIN monoclonal antibody (mAb). The QUIN toxicity assay was investigated in (a) N19 and (b) N20.1 cells treated with various concentration of QUIN (0, 0.05, 0.1, 0.2, 0.5, 1, 2 and 4 μM) for 24 hours, 48 hours and 72 hours. Lactate dehydrogenase (LDH) activity in culture supernatant was determined. The results were analyzed using linear regression analysis. (c) The schematic diagram showed the treatment conditions of QUIN and QUIN mAb on oligodendroglial cells. The effect of QUIN mAb on QUIN toxicity was examined in (d) N19 and (e) N20.1 cells. The levels of LDH released by oligodendroglial cell lines after 72 hours of incubation with 0.5 μM (N19) and 1 μM (N20.1) of QUIN and varying concentrations of QUIN mAb (30 minutes). The study was performed in triplicate and the error bars indicate SE. ***P < 0.001.
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Fig3: Neutralization of exogenous quinolinic acid (QUIN) with an anti-QUIN monoclonal antibody (mAb). The QUIN toxicity assay was investigated in (a) N19 and (b) N20.1 cells treated with various concentration of QUIN (0, 0.05, 0.1, 0.2, 0.5, 1, 2 and 4 μM) for 24 hours, 48 hours and 72 hours. Lactate dehydrogenase (LDH) activity in culture supernatant was determined. The results were analyzed using linear regression analysis. (c) The schematic diagram showed the treatment conditions of QUIN and QUIN mAb on oligodendroglial cells. The effect of QUIN mAb on QUIN toxicity was examined in (d) N19 and (e) N20.1 cells. The levels of LDH released by oligodendroglial cell lines after 72 hours of incubation with 0.5 μM (N19) and 1 μM (N20.1) of QUIN and varying concentrations of QUIN mAb (30 minutes). The study was performed in triplicate and the error bars indicate SE. ***P < 0.001.

Mentions: We then further assessed the cytotoxic threshold of such QUIN uptake on oligodendroglial cells. A standard curve, using commercial exogenous QUIN (Sigma-Aldrich, St Louis, MO, USA), was produced to assess the level of gliotoxicity by QUIN on N19 and N20.1 cells. This demonstrated a relatively similar level of tolerance in the two cell lines to QUIN (Figure 3a and b). There was a notable trend indicating dose-dependent QUIN toxicity on oligodendrocytes where the LD50 for N19 is 0.5 μM and for N20.1 is 1 μM for 72 hours. These LD50 values were chosen as the reference criteria for subsequent QUIN antagonism studies.Figure 3


Quinolinic acid toxicity on oligodendroglial cells: relevance for multiple sclerosis and therapeutic strategies.

Sundaram G, Brew BJ, Jones SP, Adams S, Lim CK, Guillemin GJ - J Neuroinflammation (2014)

Neutralization of exogenous quinolinic acid (QUIN) with an anti-QUIN monoclonal antibody (mAb). The QUIN toxicity assay was investigated in (a) N19 and (b) N20.1 cells treated with various concentration of QUIN (0, 0.05, 0.1, 0.2, 0.5, 1, 2 and 4 μM) for 24 hours, 48 hours and 72 hours. Lactate dehydrogenase (LDH) activity in culture supernatant was determined. The results were analyzed using linear regression analysis. (c) The schematic diagram showed the treatment conditions of QUIN and QUIN mAb on oligodendroglial cells. The effect of QUIN mAb on QUIN toxicity was examined in (d) N19 and (e) N20.1 cells. The levels of LDH released by oligodendroglial cell lines after 72 hours of incubation with 0.5 μM (N19) and 1 μM (N20.1) of QUIN and varying concentrations of QUIN mAb (30 minutes). The study was performed in triplicate and the error bars indicate SE. ***P < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4302518&req=5

Fig3: Neutralization of exogenous quinolinic acid (QUIN) with an anti-QUIN monoclonal antibody (mAb). The QUIN toxicity assay was investigated in (a) N19 and (b) N20.1 cells treated with various concentration of QUIN (0, 0.05, 0.1, 0.2, 0.5, 1, 2 and 4 μM) for 24 hours, 48 hours and 72 hours. Lactate dehydrogenase (LDH) activity in culture supernatant was determined. The results were analyzed using linear regression analysis. (c) The schematic diagram showed the treatment conditions of QUIN and QUIN mAb on oligodendroglial cells. The effect of QUIN mAb on QUIN toxicity was examined in (d) N19 and (e) N20.1 cells. The levels of LDH released by oligodendroglial cell lines after 72 hours of incubation with 0.5 μM (N19) and 1 μM (N20.1) of QUIN and varying concentrations of QUIN mAb (30 minutes). The study was performed in triplicate and the error bars indicate SE. ***P < 0.001.
Mentions: We then further assessed the cytotoxic threshold of such QUIN uptake on oligodendroglial cells. A standard curve, using commercial exogenous QUIN (Sigma-Aldrich, St Louis, MO, USA), was produced to assess the level of gliotoxicity by QUIN on N19 and N20.1 cells. This demonstrated a relatively similar level of tolerance in the two cell lines to QUIN (Figure 3a and b). There was a notable trend indicating dose-dependent QUIN toxicity on oligodendrocytes where the LD50 for N19 is 0.5 μM and for N20.1 is 1 μM for 72 hours. These LD50 values were chosen as the reference criteria for subsequent QUIN antagonism studies.Figure 3

Bottom Line: Our group has also found pathophysiological concentrations of quinolinic acid in MS patients.This led us to investigate the effect of quinolinic acid on oligodendrocytes; the main cell type targeted by the autoimmune response in MS.We further propose and demonstrate two strategies to limit quinolinic acid gliotoxicity: 1) by neutralizing quinolinic acid's effects with anti-quinolinic acid monoclonal antibodies and 2) directly inhibiting quinolinic acid production from activated monocytic cells using specific KP enzyme inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, Australia. g.sundaram@amr.org.au.

ABSTRACT
The excitotoxin quinolinic acid, a by-product of the kynurenine pathway, is known to be involved in several neurological diseases including multiple sclerosis (MS). Quinolinic acid levels are elevated in experimental autoimmune encephalomyelitis rodents, the widely used animal model of MS. Our group has also found pathophysiological concentrations of quinolinic acid in MS patients. This led us to investigate the effect of quinolinic acid on oligodendrocytes; the main cell type targeted by the autoimmune response in MS. We have examined the kynurenine pathway (KP) profile of two oligodendrocyte cell lines and show that these cells have a limited threshold to catabolize exogenous quinolinic acid. We further propose and demonstrate two strategies to limit quinolinic acid gliotoxicity: 1) by neutralizing quinolinic acid's effects with anti-quinolinic acid monoclonal antibodies and 2) directly inhibiting quinolinic acid production from activated monocytic cells using specific KP enzyme inhibitors. The outcome of this study provides a new insight into therapeutic strategies for limiting quinolinic acid-induced neurodegeneration, especially in neurological disorders that target oligodendrocytes, such as MS.

Show MeSH
Related in: MedlinePlus