Suppression of hepatocellular carcinoma growth via oral immune regulation towards tumor-associated antigens is associated with increased NKT and CD8+ lymphocytes.
BACKGROUND
Oral immune regulation towards viral proteins was previously shown to modulate the anti-HBV immune response. Adoptive transfer of orally immunomodulated lymphocytes suppressed the growth of hepatocellular carcinoma (HCC) expressing HBsAg in athymic mice. NKT lymphocytes play a role in the defense against tumor growth.


OBJECTIVE
To evaluate the effect of oral immune regulation towards HCC-associated antigens or HBV proteins on growth of HBsAg-expressing HCC, and to determine the role of NKT lymphocytes in immune modulation.


METHODS
Sublethally irradiated athymic Balb/c mice were injected with 10(7) human hepatoma cells followed 10 days later by transplantation of 2 x 10(6) splenocytes from naive donor mice. Immune modulation was performed via feeding of HCC-extracted proteins or HBV antigens (HBsAg + Pre S1 + Pre S2). The control group was fed with bovine serum albumin (BSA). Mice were followed for survival, tumor volume, and serum alpha-fetoprotein levels. To determine the role of NKT cells in tumor suppression, cytokine expression and FACS analysis for CD4+, CD8+, and NK1.1+ T lymphocyte subsets were performed.


RESULTS
Oral immune regulation towards HCC-extracted proteins induced complete tumor suppression in recipient mice. Mortality rates were 0% in HCC-immune-regulated mice, compared with an 80% mortality rate using HBV antigens and a 100% mortality rate in control mice. Oral immune regulation towards HCC prevented weight loss. No visible tumor mass was observed in orally immune-regulated mice as compared with 112 mm(3) in controls. Serum alphaFP levels were 0.9, 378 and 1,358 ng/ml in HCC, HBV immune-regulated and controls, respectively. Immune regulation towards HCC antigens significantly increased the NK1.1+ T lymphocytes/CD4+ and CD8+/CD4+ ratios. IFNgamma production increased two-fold.


CONCLUSIONS
Oral immune regulation towards HCC antigens effectively enhanced the anti-tumor immune response, thus suppressing the growth of HCC in mice. This effect was associated with an increased NKT,CD8+/CD4+ lymphocyte ratio and may be mediated via enhancement of IFNgamma production.
Shibolet
Oren
O
Liver Unit, Department of Medicine, Hadassah University Hospital, Jerusalem, Israel. shibolet@hadassah.org.il
Alper
Ruslana
R
Zlotogarov
Lydia
L
Thalenfeld
Barbara
B
Engelhardt
Dean
D
Rabbani
Elazar
E
Ilan
Yaron
Y
D000284:Administration, Oral; D019264:Adoptive Transfer / Q000379:methods; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D006514:Hepatitis B Surface Antigens / Q000008:administration & dosage*; D016219:Immunotherapy, Adoptive / Q000379:methods*; D007694:Killer Cells, Natural / Q000276:immunology*; D008114:Liver Neoplasms, Experimental / Q000276:immunology* / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000008:administration & dosage*; D013154:Spleen / Q000166:cytology; D000509:alpha-Fetoproteins / Q000378:metabolism
D006514:Hepatitis B Surface Antigens; D009363:Neoplasm Proteins; D000509:alpha-Fetoproteins