Diminished adenosine A1 receptor expression on macrophages in brain and blood of patients with multiple sclerosis

Abstract

The nucleoside adenosine has been shown to control the production of proinflammatory molecules through its actions on cell surface purine receptors. Previously, we have reported that the adenosine A1 receptor (A1AR) regulates tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) expression and exhibits diminished function in patients with multiple sclerosis (MS; Mayne et al., Ann Neurol 1999;45:633-639). In the present study, A1AR expression in both brain and peripheral blood mononuclear cells (PBMC) from MS and control groups was characterized by fluorescence-activated cell sorting (FACS), reverse transcriptase-polymerase chain reaction (RT-PCR), and immunohistochemical analyses. FACS analyses of PBMC revealed that A1AR expression was chiefly detectable on CD14-positive cells and was reduced by 53.1% (p < 0.01) in MS patients compared to controls. A1AR mRNA levels were reduced by 43.1% (p < 0.001) in the brains of MS patients compared to patients with other neurological diseases and controls. A1AR protein expression in brain was detected primarily in CD45-positive glial cells and was markedly diminished in MS patients. The analysis of A1AR transcripts in the brain revealed that the A1AR-beta transcript was diminished (49.2%) in MS patients compared to controls (p < 0.002). These results indicate that the A1AR, expressed principally on cells of monocyte/macrophage lineage in both brain and blood, is selectively diminished in MS patients. Reduction of the A1AR-beta transcript in MS patients suggests that dysregulated splicing may influence A1AR protein levels, potentially leading to increased macrophage activation and central nervous system inflammation.

CD45 Isoform Expression in Microglia and Inflammatory Cells in HIV‐1 Encephalitis

“…Reports of αCD45 labeling of microglia vary (1, 7, 13, 24, 33, 46, 56). We tested immunohistochemical techniques with differing sensitivity to determine whether microglial CD45 immunoreactivity varies depending on the technique and cell type.…”

“…In AIDS dementia and HIV encephalitis (HIVE), microglia and macrophages are productively infected by HIV-1 and show diffuse inflammatory activation, which ultimately leads to neuronal damage and CNS dysfunction (7, 11, 14, 43). Microglia in normal human brain express CD45 and increases in microglial CD45 expression have been detected in Alzheimer’s disease, graft-versus-host disease, multiple sclerosis, and in HIVE (1, 7, 24, 30, 33, 46). Furthermore, studies in rodent and human cells suggest that CD45 can downregulate microglial activation.…”

The role of adenosinergic pathway in human autoimmune diseases

“…However, for the other adenosine receptor-A1R, several lines of evidence have showed that A1R may have the protective function in EAE. Firstly, the expression of A1R is reduced in MS patients [40]. Secondly, A1R-deficient mice show more severe forms of progressive and relapsing EAE compared to WT mice [41].…”

“…Secondly, A1R-deficient mice show more severe forms of progressive and relapsing EAE compared to WT mice [41]. Thirdly, activation of A1R reduces inflammatory response in the CNS [40]. These results demonstrate the different role of adenosinergic pathway-related molecules in MS development.…”

Comparative non-radioactive RT-PCR assay: An approach to study the neurosteroids biosynthetic pathway in humans

“…However, obtaining CNS mRNAs presents insurmountable ethical issues. It is possible to avoid these limitations by detecting and/or measuring central mRNAs in peripheral tissues; one such source is the peripheral blood, which is easy to obtain and known to interact with the CNS (Ledoux et al, 1995;Chuang et al, 1995;Johnston et al, 2001;Blanco-Jerez et al, 2002;Gielen et al, 2003). In particular, the best source of mRNA is represented by isolated peripheral blood mononuclear cells (PBMC), since hemoglobin (Hb) from erythrocytes can inhibit PCR amplification (Furuya et al, 1999).…”