Impact of intravenous immunoglobulin on the dopaminergic system and immune response in the acute MPTP mouse model of Parkinson’s disease

Abstract

Intravenous immunoglobulin (IVIg) is a blood-derived product, used for the treatment of immunodeficiency and autoimmune diseases. Since a range of immunotherapies have recently been proposed as a therapeutic strategy for Parkinson’s disease (PD), we investigated the effects of an IVIg treatment in a neurotoxin-induced animal model of PD. Mice received four injections of MPTP (15 mg/kg) at 2-hour intervals followed by a 14-day IVIg treatment, which induced key immune-related changes such as increased regulatory T-cell population and decreased CD4+/CD8+ ratio. The MPTP treatment induced significant 80% and 84% decreases of striatal dopamine concentrations (P < 0.01), as well as 33% and 40% reductions in the number of nigral dopaminergic neurons (P < 0.001) in controls and IVIg-treated mice, respectively. Two-way analyses of variance further revealed lower striatal tyrosine hydroxylase protein levels, striatal homovanillic acid concentrations and nigral dopaminergic neurons (P < 0.05) in IVIg-treated animals. Collectively, our results fail to support a neurorestorative effect of IVIg on the nigrostriatal system in the MPTP-treated mice and even suggest a trend toward a detrimental effect of IVIg on the dopaminergic system. These preclinical data underscore the need to proceed with caution before initiating clinical trials of IVIg in PD patients.

Brain Bioavailability of Human Intravenous Immunoglobulin and its Transport through the Murine Blood–Brain Barrier

“…Published evidence of systemically administered IVIg exerting CNS effects in animal models hints toward central bioavailability. [10][11][12] However, BBB passage of IVIg remains poorly defined. In this work, we quantified the migration of systemically administered hIgG to the brain, in the absence of BBB-enhanced permeability.…”

“…For immunoblots, proteins from 5 Â 10 6 dissociated brain cells were heated at 951C for 5 minutes in Laemmli loading buffer, separated by SDS-Page on a 10% polyacrylamide gel, transferred on a polyvinylidene difluoride membrane (Immobilon-P, EMD Millipore, Billerica, MA, USA) and blocked in 5% non-fat dry milk, 0.5% bovine serum albumin, 0.1% tween 20 in PBS buffer as previously described. 12 Proteins were detected using the following primary antibodies: anti-NeuN, anti-PDGFR (receptor for platelet-derived growth factor), anti-GFAP (Sigma-Aldrich), anti-oligodendrocyte specific antibody (Abcam, Toronto, ON, Canada), anti-collagen IV (Chemicon), and anti-actin (ABM, Richmond, BC, Canada) followed by HRP-labeled secondary antibodies and chemiluminescence reagents (Lumiglo Reserve, KPL, Gaithersburg, MD, USA). Immunoblots were analyzed with a KODAK Imaging Station 4000MM Digital Imaging System (Molecular Imaging Software version 4.0.5f7, Carestream Health, Rochester, NY, USA).…”

“…[10][11][12] However, scarce pharmacokinetic data are available. In humans, the half-life of IVIg in plasma is evaluated to be 35 days 6 but the quantification of tissue distribution, specifically in the brain, remains technically challenging.…”

“…The right cerebral hemisphere (the perfused hemisphere) was collected and homogenized in 5 volumes/mg tissue of lysis buffer (50 mmol/L Tris-HCl, 150 mmol/L NaCl, 0.5% deoxycholate, 1% triton containing protease and phosphatase inhibitors) then sonicated three times for 5 Â 1-second pulses. 12 A volume of 300 ml was used for radioactive measures (WinSpectral 1414 Liquid Scintillation Counter, Wallac/Perkin Elmer, Waltham, MA, USA). The rest of the homogenate was spun 20 minutes at 100,000 g, the supernatant was removed and kept at À 801C for hIgG quantification.…”

“…6 As more than 24 million people are affected with AD worldwide, 9 the utilization of IVIg for such a prevalent disease would most certainly lead to a shortage. Although indirect evidence of IVIg reaching the parenchyma exists, [10][11][12] it is still unclear if the penetration of IVIg is a prerequisite for its clinical effects, because no quantification of the passage into the CNS has been performed. Therefore, to develop alternatives, it is essential to first determine the extent by which IVIg can access cerebral tissues.…”