Brain Research 882 2000 1–8 www.elsevier.com locate bres
Research report
Heme oxygenase HO-1 expressing macrophages microglial cells accumulate during oligodendroglioma progression
a , a
a b
Martin H. Deininger , Richard Meyermann , Katrin Trautmann , Frank Duffner ,
b c
a
Ernst H. Grote , Juergen Wickboldt , Hermann J. Schluesener
a
Institute of Brain Research , University of Tuebingen, Medical School, Calwer Strasse 3, D-72076 Tuebingen, Germany
b
Department of Neurosurgery , University of Tuebingen, Medical School, Tuebingen, Germany
c
Department of Neurosurgery , Asklepios Klinik Schildautal, Seesen, Germany
Accepted 13 June 2000
Abstract
Heme oxygenase HO-1, HSP32 catalyzes the oxidation of heme to biliverdin and carbon monoxide, a putative neurotransmitter. In the brain, HO-1 expression has been associated with neuroprotection during oxidative stress and hypoxia. However, consecutive downstream
mediation is involved in neoangiogenesis and consequent neoplastic outgrowth. We have analyzed HO-1 expression in 69 oligo- dendroglioma tissue samples, in rat intracranially transplanted C6 gliomas, and neuropathologically unaltered control brains by
immunohistochemistry. Double labeling experiments confirmed the nature of HO-1 expressing cells. Reverse transcription–polymerase chain reaction was used to demonstrate HO-1 gene expression. HO-1 immunoreactivity was predominantly observed in macrophages
microglial cells. The number of HO-1 expressing macrophages microglial cells was significantly lower in primary oligodendrogliomas than in their matched relapses P,0.0001 and lower in primary anaplastic oligodendrogliomas than in their relapses P50.0006.
Prominent accumulation of HO-1 expressing macrophages microglial cells was observed in perinecrotic areas of both experimental rat and human glioblastoma relapses. HO-1 expressing neurons, macrophages microglial cells and astrocytes were scattered in areas of
infiltrative tumor growth. Surprisingly, HO-1 mRNA was detected in only one glioblastoma multiforme relapse. We conclude from these data that HO-1 expressing macrophages microglial cells accumulate during oligodendroglioma progression in areas of focal necrosis.
However, overall biological function of this phenomenon remains to be determined.
2000 Elsevier Science B.V. All rights reserved.
Theme : Disorders of the nervous system
Topic : Neuro-oncology
Keywords : Oligodendroglioma; Rat C6 glioblastoma; Heme oxygenase-1; Immunocytochemistry; RT–PCR
1. Introduction neuronal populations. HO-2 is much more widely ex-
pressed. It is present in mitral cells in the olfactory bulb, HO-1 HSP32 is oxidative stress-inducible [15] and
pyramidal cells in the cortex and hippocampus, granule catalyzes oxidation of heme to biologically active mole-
cells in the dentate gyrus, many neurons in the thalamus, cules: iron, a gene regulator, biliverdin, an antioxidant and
hypothalamus, cerebellum and caudal brainstem [32]. carbon monoxide. Consecutive downstream mediation is
While the constitutively expressed HO-2 has been reported involved in vasodilation, stimulation of guanylate cyclase,
to be exclusively regulated by glucocorticoids, the induc- and neuronal transmission [7].
ible HO-1 isozyme is associated with a wide range of In normal brain, HO-1 is present at the limit of
pathological conditions in the mammalian brain. Induction immunodetection and is discretely localized in selected
of HO-1 expression has been associated with neuroprotec- tion during hyperthermia in glial cells [4] and during
hypoxia [23]. Consequently, HO-1 expression in neurons,
Corresponding author. Tel.: 149-7071-298-2283; fax: 149-7071-294-
astrocytes and macrophages was observed in a wide range
846. E-mail address
: hirnforschunguni-tuebingen.de M.H. Deininger.
of experimental diseases of the rodent brain such as
0006-8993 00 – see front matter
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2 M
traumatic injury [5], ischemia [21] and in human Alzheim- numerous multinucleated cells, high mitotic activity, vas-
er’s disease [26]. Moreover, HO-1 expression in infiltrating cular proliferation and areas of focal necrosis. Seven
macrophages has been associated with disease severity in patients with oligodendroglioma received radiotherapy
atherosclerosis [33] and constitutes a marker of oxidative following the resection of the primary tumor, and 14
stress in asthma [8]. In brain tumors, elevated HO-1 patients received no post surgical treatment. In five pa-
expression was observed, but spatial and cellular expres- tients, no postsurgical therapy was mentioned thus sug-
sion patterns remain unresolved [6,22]. gesting that no post surgical therapy was applied. Thirteen
In order to provide a pathological basis for the in- patients
with anaplastic
oligodendroglioma received
volvement of HO-1 in oligodendrogliomas, we have radiotherapy after resection of the primary tumor, three
analyzed its expression in 69 oligodendroglioma tissue radiotherapy and chemotherapy with ACNU and VM26,
samples, in rat intracranially transplanted C6 gliomas, four and three received no postsurgical treatment. Involved-
rat brains and four neuropathologically unaltered human field radiotherapy was applied at doses of 36–60 Gy.
brains by immunohistochemistry. Twenty-six primary WHO grade II oligodendrogliomas and 16 primary WHO
2.2. Human control brains grade III anaplastic oligodendrogliomas were included.
Nineteen grade II tumors progressed, 10 were again grade Four control brains were obtained from autopsies at the
II oligodendrogliomas, and nine had progressed to higher Institute of Brain Research in Tuebingen Table 2. All
grade lesions. Eight anaplastic oligodendrogliomas pro- tissues were fixed in buffered 4 formalin pH 7.4 and
gressed, five were again WHO grade III tumors, and three embedded in paraffin by routine methods.
had progressed to glioblastoma multiforme. Double label- ing experiments confirmed the nature of HO-1 expressing
2.3. Cell culture cells. Reverse transcription–polymerase chain reaction
RT–PCR was used to demonstrate HO-1 mRNA. Rat C6 glioblastoma cell lines were obtained from the
American Type Culture Collection ATCC, Manassas, USA and raised in RPMI 1640 medium with Glutamax II
2. Materials and methods Gibco BRL, Paisley, UK containing 10 fetal calf serum
