AdCD40L gene therapy counteracts T regulatory cells and cures aggressive tumors in an orthotopic bladder cancer model.
OBJECTIVE
The aim of this study was to develop an immunostimulating gene therapy for the treatment of orthotopic bladder carcinoma by transferring the gene for CD40L into the tumor site. CD40L stimulation of dendritic cells induces interleukin-12 expression that drives Th1 type of immune responses with activation of cytotoxic T cells.


METHODS
The gene for murine CD40L was transferred into bladders of tumor-bearing mice using an adenoviral vector construct. To facilitate viral uptake, the bladders were pretreated with Clorpactin. Survival of mice as well as transgene expression and immunologic effect, such as resistance to tumor challenge and presence of T regulatory cells, were monitored.


RESULTS
On viral vector instillation, CD40L expression could be detected by reverse transcription-PCR. As a sign of transgene function, interleukin-12 (IL-12) expression was significantly increased. AdCD40L gene therapy cured 60% of mice with preestablished tumors. The cured mice were completely resistant to subcutaneous challenge with MB49 tumor cells, whereas the growth of a syngeneic irrelevant tumor was unaltered. Furthermore, the mRNA expression level of the T regulatory cell transcription factor Foxp3 was evaluated both in tumor biopsies and lymph nodes. There were no differences within the tumors of the different treatment groups. However, Foxp3 mRNA levels were down-regulated in the lymph nodes of AdCD40L-treated mice. Correspondingly, T cells from AdCD40L-treated mice were not able to inhibit proliferation of naive T cells as opposed to T cells from control-treated, tumor-bearing mice.


CONCLUSIONS
AdCD40L gene therapy evokes Th1 cytokine responses and counteracts T regulatory cell development and/or function.
Loskog
Angelica S I
AS
Rudbeck Laboratory, Clinical Immunology Division, Uppsala University, Uppsala, Sweden. angelica.loskog@klinimm.uu.se
Fransson
Moa E
ME
Totterman
Thomas T H
TT
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D023201:CD40 Ligand / Q000235:genetics*; D002277:Carcinoma / Q000276:immunology / Q000628:therapy*; D004195:Disease Models, Animal; D004848:Epithelium / Q000473:pathology; D051858:Forkhead Transcription Factors / Q000235:genetics; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D018664:Interleukin-12 / Q000235:genetics; D008198:Lymph Nodes / Q000737:chemistry; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D014161:Transduction, Genetic; D001743:Urinary Bladder / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000276:immunology / Q000628:therapy*
D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D012333:RNA, Messenger; D023201:CD40 Ligand; D018664:Interleukin-12