CD5 Promotes IL-10 Production in Chronic Lymphocytic Leukemia B Cells through STAT3 and NFAT2 Activation

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BlankCD5 Promotes IL-10 Production in Chronic Lymphocytic Leukemia B Cells

through STAT3 and NFAT2 Activation

1.. Soizic Garaud*,

2.. Ahsen Morva*,

3.. Sébastien Lemoine*,

4.. Sophie Hillion*,

5.. Anne Bordron*†,

6.. Jacques-Olivier Pers*‡,

7.. Christian Berthou*†,

8.. Rizgar A. Mageed§,

9.. Yves Renaudineau*‡ and

10.. Pierre Youinou*‡

+ Author Affiliations

1.. *EA2216 Immunology and Pathology, IFR 148 ScInBioS, European University of

Brittany, F29609 Brest, France;

2.. †Department of Oncology, European University of Brittany, F29609 Brest,

France;

3.. ‡Laboratory of Immunology, Brest University Medical School Hospital,

F29609 Brest, France; and

4.. §Barts and the London Queen , School of Medicine and Dentistry,

London, United Kingdom

1.. Address correspondence and reprint requests to Prof. Pierre Youinou,

Laboratory of Immunology, Brest University Medical School Hospital, BP824,

F29609 Brest, France. E-mail address: youinou@...

Abstract

B lymphocytes from chronic lymphocytic leukemia (CLL) display some CD5

transcripts for CD5 containing the known exon 1 (E1A) and other CD5 transcripts

containing the new exon 1 (E1B). These malignant B cells, as well as B cell

lines transfected with cDNA for E1A-cd5 or with cDNA for E1B-cd5 produce IL-10,

raising the possibility that CD5 participates in the secretion of IL-10. We

identified transcription factors involved in this production in CD5+ B

lymphocytes from CLL patients and in E1A-cd5–transfected or E1B-cd5–transfected

Jok cells. STAT3 is activated via phosphorylation of serine 727 but also NFAT2

through its translocation into the nucleus. Chromatin immunoprecipitation

experiments confirmed the role of STAT3 and allowed the discovery of a role for

NFAT2 in IL-10 production. Both transcription factors bind not only to the

enhancer of the Il-10 gene but also to the promoter of the Il-5 and Il-13 genes.

Furthermore, transfection of B cell lines with E1A-cd5 or E1B-cd5 established

that activation of STAT3 and NFAT2 is regulated by CD5. The same holds true for

the production of IL-10, IL-5, and IL-13 and the expression of the receptors for

these cytokines. This interpretation was confirmed by two experiments. In the

first, downregulation of CD5 by small interfering RNAs lowered the production of

IL-10. In the second experiment, transfection of the GFP-NFAT2 gene into B

lymphocytes induced nuclear translocation of NFAT2 in CD5+ but not in CD5- B

cells. Thus, CD5 expression is associated with NFAT2 activity (and mildly STAT3

activity), indicating that CD5 controls IL-10 secretion.