Downregulation of cannabinoid receptor 2 (CB2) messenger RNA expression during in vitro stimulation of murine splenocytes with lipopolysaccharide.
Cannabinoid receptor 2 (CB2) has been identified as the most abundant cannabinoid receptor subtype in the immune system. Bacterial lipopolysaccharide (LPS) is a potent stimulant of B cells, inducing proliferation and differentiation into antibody secreting cells. It has been reported that CB2 receptor expression is upregulated during human, tonsillar B cell activation through CD40. It was of interest to investigate the expression of CB2 mRNA using another B cell activator, LPS. Using northern blot analysis, we measured CB2 mRNA levels in murine splenocytes and enriched B cells. Results indicated that the 4.0 kb CB2 transcript was 2 fold higher in abundance in murine B cells than in whole splenocyte preparations. This observation confirmed data from others and from our previous RT-PCR studies that the expression of CB2 mRNA is more abundant in B cells. Upon LPS stimulation, CB2 transcripts were decreased 46% and 42% at 4 hours and 24 hours, respectively, when compared to unstimulated populations. An examination by flow cytometry of the CD69, early activation marker, on splenocytes, showed that the majority of the B cells were activated at 24 hrs. Thus, these results suggested that LPS stimulation of murine B cells caused a decrease in CB2 mRNA expression in contrast to the increase observed following human B cell stimulation through CD40.
Lee
S F
SF
Department of Medical Microbiology & Immunology, University of South Florida, College of Medicine, Tampa 33612, USA.
Newton
C
C
Widen
R
R
Friedman
H
H
Klein
T W
TW
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D037181:Lectins, C-Type; D008070:Lipopolysaccharides / Q000633:toxicity*; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000235:genetics*; D013154:Spleen / Q000166:cytology / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D000099192:CD69 Antigens
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D000099192:CD69 Antigens